Doctor DK Series

Operating Manual

Revision 2.8
October 2006

3 Raw Holdings
East Calder
West Lothian EH53 0HY, UK
T: +44 1506 885000
F: +44 1506 885501
W: www.iconresearch.co.uk
 NOTICE
Information contained in this document is believed to
be accurate and reliable. However, due to ongoing
product developments and revisions, Icon Research
Ltd cannot guarantee the accuracy of this document
after the date published nor can it accept
responsibility for errors or omissions.

This document, and the software and/or hardware

which it describes, is subject to change without notice.

Icon Research Ltd acknowledges that various

products or trademark names referred to in this
document are subject to copyright and/or trademark
by their respective registered holders.
 CONTENTS
CHAPTER 1 - Getting Started......................................................................................1-1
1.1 System Components – Systems with Optical Crank Pickup 1-1
1.2 System Components – Systems with Inductive Crank Pickup 1-2
1.3 Equipment Check 1-3
1.4 Initial Doctor Set-up 1-3
1.5 Checking the Crank Pickups 1-4
1.6 Taking the First Reading 1-4
1.7 To Take the Next Reading 1-4
1.8 Downloading 1-5
1.9 TDC Correction Service 1-5

CHAPTER 2 - Description............................................................................................2-1
2.1 General 2-1
2.2 Mechanical Layout 2-2
2.3 Powering the Instrument 2-3
2.4 EPU Functionality 2-3
2.5 Modes of Operation 2-4

CHAPTER 3 - Operation of the Instrument ..................................................................3-1

3.1 Overview 3-1
3.2 Keypad Functions 3-1
3.3 MAIN Screen (Normal Mode) 3-2
3.4 MAIN Screen (Advanced Mode) 3-3
3.5 After Pressing GO 3-4
3.6 SETUP Screen (Normal Mode) 3-5
3.7 SETUP Screen (Advanced Mode) 3-8
3.8 UTILITIES Screen (Normal Mode) 3-11
3.9 UTILITIES Screen (Advanced Mode) 3-15
3.10 VIEW Screen (Normal Mode) 3-16
3.11 VIEW Screen (Advanced Mode) 3-18

CHAPTER 4 - Operation of Installed Doctor Instruments ............................................4-1

4.1 General 4-1
4.2 System Layout 4-1
4.3 Operating Sequence 4-2

CHAPTER 5 - Fault Messages ....................................................................................5-1

5.1 Crank Pickup Faults 5-1
5.2 Pressure Sensor Faults 5-1

CHAPTER 6 - Installation of Flywheel Pickups............................................................6-1

6.1 Introduction 6-1
6.2 Optical Pickup Installation 6-2
6.3 Inductive Pickup Installation 6-4
6.4 Troubleshooting the Crank Pickups 6-10
6.5 Performance of Inductive Pickups 6-11

CHAPTER 7 - Electrical Connections ..........................................................................7-1

7.1 Channel Inputs 7-1

CHAPTER 8 - Technical Specification .........................................................................8-1

 Pressure sensor and lead Components for
Portable Doctor System
Tube spanner
Pickup

for pressure
with Optical Crank Pickup
Thompson Adapter
sensor removal

Fischer Selection of Mains Plugs

Charge lead supplied 110 / 220 V ac
connector
with connector
and power supply
PEC-1
3m extension
cable
TNC

1-1
CHAPTER 1 - Getting Started

Connector

OCP-2 Optical
Crank Pickup
Chapter 1 – Getting Started

with 10m cable

with Mil Spec connector

OFE-1 optic fibre extension

1.1 System Components – Systems with Optical Crank

Ensure lugs on washer align with holes

in OCP-2 when fitting
 Components for
Pressure sensor Portable Doctor System
and lead with Inductive Crank Pickups
Tube spanner Typical Items for 1 Main and
Pickup

Thompson adapter
for pressure 3 Auxiliary Engines
sensor removal
Fischer
Charge lead
connectors Selection of mains plugs
with connector
and power supply supplied 110 / 220 V AC

PEC-1
3m extension
cable
TNC Doctor DK-2
Connector (DK-2/FV for systems
with fuel pressure

1-2
sensor) Fit a marker bolt into
the flywheel of each
engine.
Make brackets and
Junction box for mount inductive pickups
at flywheel.
Chapter 1 – Getting Started

auxiliary engine(s) ICP-1 dia 12mm crank pickup

for auxiliary engine Bolt and brackets
not supplied.
On main engine, one
Mount near to Mount near pickup senses the bolt,
indicator cocks flywheel the other senses the
flywheel teeth.

See ICP installation guide

1.2 System Components – Systems with Inductive Crank

ICP-1 dia 18mm crank pickups for full fitting details.

Dual junction box for main engine
for main engine
with 20m Interconnecting Cable

Other configurations may be supplied to suit.

 Chapter 1 – Getting Started

1.3 Equipment Check

If this is the first time you have used the Doctor system, first check that you have all
of the items shown in one of the diagrams on the previous pages.

Your Doctor instrument will have been delivered with the battery in a discharged
condition. Before any readings are taken, the battery should be charged up. Connect
the power supply to the mains using the appropriate plug, and charge the unit until
the CHARGE lamp goes out. This should take around 2.5 hours.

You will first need to ensure that the crank pickups are correctly installed. There are
two types of crank pickup:

Optical Pickup: Ensure there is a clean piece of optical reflective tape on the
flywheel. The optical pickup should be at least 25mm away from the flywheel. There
is adjustment available on the rear of the main optical unit – if the LED on the unit
does not flash regularly when the engine is turning, adjust the unit until it does.

Inductive Pickup: The TDC pickup must have a metal marker on the flywheel of a
larger diameter than the pickup. If dual pickups are used, the second one senses the
flywheel teeth. The teeth must be larger than the pickup diameter. The correct gap
settings are 2mm for 12mm diameter pickups and 3mm for 18mm diameter pickups.

1.4 Initial Doctor Set-up

• Switch on the Doctor instrument.
• Wait till the memory and stores check finishes.
• Press [UTIL] to select the UTILITIES SCREEN.
• Use the ↑ and ↓ cursor keys to select the following:
• MEASUREMENT MODE AVERAGED
• OPERATING MODE NORMAL

The operations required on the keyboard for these settings is described at the bottom
of the screen.

• Press [SET] to select the SETUP SCREEN.

• Use the ← and → cursor keys to select following:
• SETUP NO 1 ENGINE 1
• AVERAGES enter 20 for 2-strokes and 40 for 4-strokes.
• ANG RES 1° is good for most applications.
• PICKUP MODE DUAL or TDC depending on your system
• MEASURE CMP ONLY is best for the initial reading (FV
only)
• SENSITIVITY See the pressure sensor calibration sheet
• ENGINE TYPE 4 STROKE or 2 STROKE

Your Doctor instrument is now set up ready for initial readings.

1-3
 Chapter 1 – Getting Started

1.5 Checking the Crank Pickups

Before taking a reading, you should check that the crank pickup(s) are giving the
right signals. If they are not, your measurements may be corrupted.

• Connect the crank pickup lead.

• Press [UTIL] to enter the UTILITIES screen.
• Use the ↑ and ↓ cursor keys to select CRANK SETUP.
• Press [ENT] twice.
• Check for correct RPM and stable readings on the screen.
• Select CLEAR MEMORY.
• Press [ENT] twice to clear all the memories.

1.6 Taking the First Reading

• You are now ready to take a reading.
• Start at cylinder 1 (on A bank if it is a V engine).
• Connect the Pressure Sensor to the Doctor using the extension lead (PEC-1).
• Open the indicator cock briefly to clear it.
• Attach the Pressure Sensor to the indicator cock.
• Open the cock fully.
• Make sure the instrument is switched on and ENGINE 1 selected in the MAIN
screen.
• Enter the scavenge pressure using the ← and → cursor keys to adjust the
value.
• PRESS [GO].

The instrument will automatically check the Crank Pickups and measure engine
speed. After this it will take readings on each cycle of the engine until the selected
amount of averages are acquired. When finished, the screen will show a graph. From
the shape of this you will know if the reading is OK. The most common fault is
forgetting to open the cock.

1.7 To Take the Next Reading

• Close the cock on the cylinder just read.
• Remove the pressure sensor.
• Open the next indicator cock briefly to clear it.
• Attach the Pressure Sensor to the indicator cock.
• Open the cock fully.
• PRESS [GO].

Repeat this until all the cylinders on the engine have been read.

Each cylinder’s reading should now be stored in the Doctor in consecutive stores.

1-4
 Chapter 1 – Getting Started

1.8 Downloading
• To download, the engine must first be set up in the Doctor PC software. See
the Doctor Step-by-Step Guide for details.
• If you purchased the database set-up service, you will use the database that
has been provided with your instrument.
• Connect the Doctor instrument to the PC with the RS232 cable supplied.
• In the software, select the correct engine and highlight the engine name.
• Click on the button with a “yellow Doctor box” in it.
• On newly installed software, you will need to enter the serial number at this
time. The serial number is on a label on the CD pocket.
• Select Memory 1 and Cylinder 1.
• Click on Auto Connect.
• Click on Transfer.
• Enter the Scavenge pressure.
• Click OK and everything will be transferred.

1.9 TDC Correction Service

Once you have initial readings from your engines, Icon provides a TDC correction
service that is included in your purchase of a Doctor system.

To make use of this service, make an archive of your initial results and Email the
resulting file to: doctor@iconresearch.co.uk for correction. We also keep a copy of
your initial database in case you have any PC problems in the future and lose your
database.

1-5
Chapter 1 – Getting Started

1-6
 Chapter 2 – Description

CHAPTER 2 - Description
The Doctor system combines ease of use with extremely high accuracy and hidden
sophistication.

2.1 General
The main elements in the system are as follows:

• The Doctor Instrument

• Pressure Sensor
• Crank Pickup
• PC Doctor Software

There are two types of portable instrument available.

• DK-2 - Single channel for cylinder pressure.

• DK-2/FV - Dual simultaneous channels for taking fuel pressure (or vibration)
readings in addition to cylinder pressure.

There is also an On-Line version available.

Earlier versions included an installed system that is now discontinued, but for which
operating instructions are included in this manual. These were:

• DK-2/M - Single channel installed unit with direct PC connection.

• DK-2/M/FV - Dual simultaneous channel installed unit with direct PC
connection.

All units can accept either dual or single crank pickups and these can be either
inductive or optical.
System Overview

2-1
 Chapter 2 – Description

2.2 Mechanical Layout

Each of the DK series instruments, which are called Engine Processor Units or
EPU’s, is housed in a highly ruggedised waterproof ABS plastic enclosure. The
enclosure is "lunchbox" style for ease of carrying and transportation. The unit is
sealed to IP67 with the lid closed and to IP65 with the lid open. This means that
water, oil and dust can be sprayed onto the unit while it is operating without danger of
leaking into the internal circuitry.

The figure below shows the internal configuration of the instrument. On the left side
are the pressure inputs (one for the DK-2, two for the DK-2/FV) together with the
connector for the crank interface pick-ups. In the centre is a high-contrast graphic
LCD display, below which is a fully-sealed rubber keypad. The keypad incorporates
large keys with tactile feedback for operation with gloved hands. On the right are the
power input, serial computer interface, ON/OFF switch and indicator lights (LED’s) for
power and battery charging.
Internal Layout

Power Input
and Indicators

2-2
 Chapter 2 – Description

2.3 Powering the Instrument

The EPU can be powered from its internal rechargeable battery pack or from mains
power using the charger supplied. The charger can take any input voltage in the
range 100V to 240Vac. Three different types of power cord are supplied, namely UK,
US and Euro. These cover virtually any mains source encountered in the world.

The DC output of the charger is rated at 9V, 3A. The connection is shown in the
diagram below.

If the charger supplied is lost, it is possible to use a supply as per the above rating
and connection to charge the instrument. The dc plug is a standard type, the outer
cylinder diameter being 5.5mm and the inner diameter being 2.5mm.

When mains power is connected via the charger, the POWER LED will be
illuminated. Battery charging is shown by the CHARGING LED being illuminated.
When the internal battery is fully charged, charging will stop automatically and the
CHARGING LED will be extinguished. Battery charging will still take place when the
ON/OFF switch is in the OFF position.

The internal battery takes approximately 2.5 hours to recharge. With one transducer,
the unit will last approximately 12 hours on one charge.

The batteries used are high quality Ni-Cad batteries. A warning is given at the top
right of the screen when the battery voltage becomes low. The level for this is
normally set at 5.9V but this can be changed if desired. Ni-Cad batteries last longest
if they are charged fully after a full discharge. For this reason it is advisable to wait till
the battery warning appears on the screen before charging fully.

The unit contains a battery back-up system so that stored data is not lost when the
instrument is turned OFF, even if the battery is discharged.

2.4 EPU Functionality

The data acquisition section receives analogue data from the pressure sensor and
converts this to a series of digital numbers using an analogue-to-digital converter.
The EPU automatically adjusts to the amplitude of the incoming signal to maximise
the dynamic range (and thus reduce unwanted noise) in the system. The data
acquisition process is synchronised to the flywheel multiplier.

The crank interface comprises a digital multiplier circuit which multiplies the
synchronisation pulses from the crank pick-ups with high accuracy and no phase
shift. For example, when dual pickups are used, pulses from a flywheel (perhaps 60
per rev) can be multiplied up to 3600 per rev (or one every 0.1°) and maintain
constant phase with the once-per-rev signal. This means that the angle for the
pressure readings is corrected 60 times per revolution which leads to greatly
increased accuracy especially on low speed engines where speed can vary during a
revolution. This feature enables the DOCTOR to achieve significantly better analysis
results than conventional systems based on a once-per-rev input only.

2-3
 Chapter 2 – Description

2.5 Modes of Operation

Doctor instruments have two modes of operation – Normal and Advanced. In the
Normal Mode, the EPU takes readings which are transferred to the PC Software for
analysis. In the Advanced Mode, the EPU is programmed with engine details and
calculates many of the parameters immediately and displays the results in a table on
the instrument screen. Results are still normally transferred to a PC for more detailed
analysis.

2-4
 Chapter 3 – Operation of Instrument

CHAPTER 3 - Operation of the Instrument

3.1 Overview
The EPU contains 105 memory stores into which measurements are written. There
are 20 stores available for different engine set-ups. In the Advanced Mode, one set-
up is used per engine.

The procedure is to select a particular engine in the MAIN screen, enter the current
scavenge pressure and take measurements by simply pressing the [GO] key. To
take the next measurement, move the pressure sensor to the next cylinder and open
the cock. Then just press the [GO] key.

Measurements are stored sequentially in the memory stores, and increment

automatically between readings. It is possible to go back through the stores and
overwrite results if mistakes are made.

Two types of measurement are possible. The first is an AVERAGED measurement

from a cylinder (and from a second sensor on FV units) where a number of cycles
can be averaged.

The second is a NON-AVERAGED X10 set of readings whereby ten single cycles are
taken in succession on a cylinder (and from a second sensor on FV units) - this is
sometimes called a Firing Analysis and is useful in detecting intermittent problems.

3.2 Keypad Functions

Operation of the instrument is carried out entirely via the keypad. This is a sealed
rubber type with tactile feedback. The layout of the keypad is shown below.

Keypad Layout

The top row of buttons is used to access the four main screens.

[←], [→], [↑], [↓] are the cursor keys which select set-up parameters and displays for
review.

[ENT] provides the ENTER function for parameter selection as prompted on the
display.

[ESC] escapes from a particular mode of operation, including data acquisition.

[GO] initiates data acquisition.

3-1
 Chapter 3 – Operation of Instrument

3.3 MAIN Screen (Normal Mode)

The MAIN screen is shown below. The up and down cursor keys are used to select
a menu item and the left/right keys change the parameter.

MAIN Screen

ENG SELECT Selection

The ENG SELECT menu item selects the engine to be measured, with parameters
as defined in the SETUP screen. Change the engine selection using the ← and →
cursor keys. Up to 20 different engines can be defined, and each engine can be
given a name with up to 10 characters. Engine names may be edited in the
UTILITIES screen.

SCAV PRESS Selection

SCAV PRESS (Scavenge Pressure or Boost Pressure) can be entered in the range
0.1 to 10.0 bar. This value is used to calculate the Pmax value displayed after each
reading and is usually read from a dial on the engine. Change the SCAV PRESS
value using the ← and → cursor keys. Note that it is not necessary to enter this value
if Pmax values on the EPU are not required. The value of scavenge pressure is
entered independently in the analysis software.

MEMORY NO Selection

MEMORY NO is the number of the memory store (up to 105) in which the next
measurement will be stored. It is automatically incremented after each
measurement. If desired, this memory "pointer" can be changed at any time by using
the ← and → cursor keys. This is useful for overwriting data if an error has been
made.

Once the desired engine is selected and the scavenge pressure value entered, just
press [GO] to take a reading. The reading will be entered into the memory number
which was shown prior to the reading. After the reading, the memory number
automatically increments by one, however there is no need to return to the MAIN
SCREEN to initiate another reading, just move the pressure sensor to the next
cylinder cock, open the cock and press [GO] again.

3-2
 Chapter 3 – Operation of Instrument

3.4 MAIN Screen (Advanced Mode)

CYL SELECT Selection

In the advanced mode of operation, there is an additional selection possible where

the number of the cylinder being measured is displayed. After clearing the memories,
this will always start at CYL1 and it is recommended that readings are always taken
starting at cylinder No 1 on the engine and that readings are kept in order after that to
simplify downloading. If a reading needs to be repeated or several readings are
required on a cylinder, the number in CYL SELECT must match the number of the
cylinder in order to calculate results correctly. The cylinder number can be altered by
using the ← and → cursor keys.

From the MAIN Screen, pressing the [GO] button will initiate a reading.

3-3
 Chapter 3 – Operation of Instrument

3.5 After Pressing GO

After pressing [GO], the instrument will display 3 screens in sequence, and then
display the result of the measurement.

First the TDC and flywheel periods are measured to calculate the initial RPM and
sampling rate. Sampling rate varies during acquisition as the DOCTOR tracks
engine speed. Data is then read and stored. At the foot of the screen, there is a
counter of the current cycle being measured. Once the counter reaches the selected
number of averages, acquisition is complete and the result will be presented
immediately after. Pressing [ESC] at any point stops the acquisition process.

3-4
 Chapter 3 – Operation of Instrument

3.6 SETUP Screen (Normal Mode)

The SETUP screen is selected by pressing the [SET] key. This screen enables
engine parameters and measurement parameters for a particular engine to be set up.
The ↑ and ↓ cursor keys select the menu item to be changed, and this is highlighted
in inverse video. The ← and → cursor keys change the parameter itself. The screen
format is shown below.

SETUP Screen (FV version shown)

SETUP Selection

The SETUP NO 1 to SETUP NO 20 selection is used to set the conditions for

measurement for a particular engine type. Change the SETUP selection using the ←
and → cursor keys.

The screen above shows a typical setting for a 4-stroke engine. On non FV EPU’s,
the selections for MEASURE, F/V SENSITIVITY and POLARITY are not available.

Up to 20 individual engine set-ups can be defined and the name of the engine can be
edited in the UTILITIES screen. An engine set-up can be set to ON or OFF. When
selected to ON, it will appear as one of the selectable engines in the MAIN screen.
When selected to OFF, it is not selectable in the MAIN screen. ON and OFF are
toggled using the [ENT] key when the SETUP section is highlighted.

The name of an engine may be changed using the UTIL screen – see the section on
EDIT ENGINE NAMES.

AVERAGES Selection

The number of cycles over which a measurement is taken is defined in the

AVERAGES selection. The range is 1 to 100. One cycle of a 2-stroke engine is one
revolution whereas one cycle of a 4-stroke engine is two revolutions. A selection of 1
for the AVERAGES value will take a reading without any averaging. The number of
cycles is modified by pressing the ← and → cursor keys while AVERAGES is
selected. Holding a key down accelerates the update rate.

Averaging helps to remove noise from the signals and provides the mean
performance for a particular cylinder. AVERAGES values between 20 and 50 are
typical.

3-5
 Chapter 3 – Operation of Instrument

ANG RES Selection

In the ANG RES menu selection, the angular resolution of the measurement (in
degrees) is selected. For example, if value 0.5 is selected, then 720 data samples
per revolution of the shaft will be taken and the resulting graphs will have a point
every ½°. If the resolution is too high for the particular engine speed, a warning
message is given to select a lower resolution. A resolution of 0.1° will be available
for engine speeds of up to 600 RPM or a little higher. Change the ANG RES
selection using the ← and → cursor keys.

The available selections are 0.1, 0.2, 0.5, 1 and 2. As a guide, 0.5º is normally used
for 2-stroke main engines and 1º for 4-stroke auxiliary engines. This gives the
resolutions required for analysis and keeps the database size within reasonable
limits. Higher resolutions may be required for special applications but the rate of
change of pressure plots in the PC software may become noisy and database size
will increase.

When dual pickups are used, the resolution is defined partly by the number of teeth
on the flywheel. For example, a flywheel with 84 teeth has 4.285° between each
tooth so the nearest resolution for a requested 1° resolution would be 4 samples for
each tooth or a resolution of 1.07° per sample. The PC software and the advanced
mode in the EPU can handle fractional resolutions so results stay accurate.

PICKUP MODE Selection

PICKUP MODE can be set to TDC ONLY or DUAL depending on whether a single
(once-per-rev) pickup is being used or whether two have been installed (i.e. a once-
per-rev and flywheel teeth pickup). The mode should be selected to match the
installation. Change the PICKUP MODE selection using the ← and → cursor keys.

MEASURE Selection (FV units only)

On dual channel units it is possible to take simultaneous readings of cylinder

pressure and another parameter. The standard selections are for Fuel Pressure or
Vibration as the second parameter but in practice, any other compatible pickup can
be used and a signal, synchronised to the engine cycle will be stored. The available
selections on the screen are CMP ONLY, CMP + FUEL and CMP + VIB. Change the
MEASURE selection using the ← and → cursor keys.

3-6
 Chapter 3 – Operation of Instrument

SENSITIVITY CMP Selection

SENSITIVITY enables the sensitivity of the pressure sensor to be entered in order

that the Pmax value displayed after each reading can be calculated. The value
required will be found on the calibration certificate of your pressure sensor and for
standard sensors will be around 20mV/bar. Choose the value at the higher
temperature and pressure if there is a choice. The default value is 20mV/bar so that if
a value is not entered, the readings should be close to correct. Change the
SENSITIVITY value using the ← and → cursor keys.

POLARITY CMP Selection

POLARITY is a means by which the incoming signal from the pressure sensor can be
inverted if desired. This is to cope with different types of pressure sensor and charge
amplifier. In general, when using a pressure sensor, the NORMAL selection should
be used. When using a charge amplifier, INVERTED should be selected. If the
signal from a particular pressure sensor appears upside down, use the other
selection. Change the POLARITY CMP selection using the ← and → cursor keys.

SENSITIVITY F/V (FV units only)

This item is only active if either CMP + FUEL or CMP + VIB has been selected in the
MEASURE Selection (see above). The default sensitivities are 2.5mV/bar for fuel
pressure readings and 50mV/g for vibration readings. Change the SENSITIVITY F/V
value using the ← and → cursor keys.

POLARITY F/V (FV units only)

This item is only active if either CMP + FUEL or CMP + VIB has been selected in the
MEASURE Selection (see above). POLARITY is a means by which the incoming
signal from the Fuel Pressure sensor or Vibration sensor can be inverted if desired.
This is to cope with different types of sensors and charge amplifiers. In general,
when using a pressure sensor, the NORMAL selection should be used. When using
a charge amplifier, INVERTED should be selected. If the signal from a particular
pressure sensor appears upside down, use the other selection. Change the
POLARITY CMP selection using the ← and → cursor keys. For Vibration signals,
either selection can be used.

ENGINE TYPE Selection

ENGINE TYPE selects whether the engine is a 2-STROKE or 4-STROKE. Change

the ENGINE TYPE selection using the ← and → cursor keys.

3-7
 Chapter 3 – Operation of Instrument

3.7 SETUP Screen (Advanced Mode)

The EPU can be operated in Advanced Mode by selection through the UTILITIES
screen.

The Advanced Mode allows cylinder results to be calculated directly in the instrument
and provides a table showing results as well as still having graphs available. The
SETUP SCREEN changes once the advanced mode is selected.

There are now two screens for setting measurement parameters as shown below.

To move between the screens, you can press the [SET] key or alternatively, scrolling
to the “next” or “previous” selections will jump to the next screen.

SETUP Screen 1 Advanced Mode (FV version shown)

In the FV version of the EPU, one additional item appears in the SETUP SCREEN 1.
This is SPRING.

SPRING VALUE Selection

This value is useful when fuel pressure readings are being taken and will identify the
angle at which the spring pressure is reached. The value to enter is the snap
pressure of the injectors and with this value set, the instrument will be able to identify
the delivery angle for fuel entering the cylinder. Change the SPRING value by using
the ← and → cursor keys.

3-8
 Chapter 3 – Operation of Instrument

SETUP Screen 2 Advanced Mode

In this screen, the engine parameters that are needed for calculation of results are
set.

BORE Selection

The bore diameter is entered in mm. Use the ← and → cursor keys to increase or
decrease the value.

STROKE Selection

The stroke length is entered in mm. Use the ← and → cursor keys to increase or
decrease the value.

CON ROD LEN Selection

The con rod length is entered in mm. Use the ← and → cursor keys to increase or
decrease the value. The correct dimension to use is the distance between centres.

TRIG REL TO TDC Selection

This value is determined after initial readings have been taken and requires the PC
software to ensure it is correct. The procedures for determining the correct TDC
offset are described fully in the Step-by-Step software guide. The value is entered in
degrees and can be adjusted in steps of 0.1°. Use the ← and → cursor keys to
increase or decrease the value. The same value is used for all cylinders in an engine.

CYL CONFIG Selection

The engine configuration will either be IN-LINE or V-ENGINE. Use the ← and →
cursor keys to make your selection.

CYL PER BANK Selection

This is used to input the number of cylinders the engine has. On an IN-LINE engine,
there is only one bank so just enter the number of cylinders. On a V-ENGINE, there
are two banks but just enter the number per bank. Use the ← and → cursor keys to
increase or decrease the value shown.

3-9
 Chapter 3 – Operation of Instrument

ENGINE ROTATION Selection

On V-ENGINES, it is necessary to let the system know which way the engine is
rotating. This selection is not active for IN-LINE engines. The rotation is defined as
the way the top of the flywheel rotates relative to the A bank and B bank of the
engine. Use the ← and → cursor keys to select either A→B or B→A.

BANK ANGLE Selection

Again this is only for V-ENGINES and is the angle between the cylinder banks.
Normal values are 45° to 60° although there are other angles used. Use the ← and
→ cursor keys to increase or decrease the number until the required value is
reached.

FIRING ORDER Selection

With FIRING ORDER highlighted, press the [ENT] key and a screen will appear as
shown below.

EDIT FIRING ORDER

To get the cylinder numbers in the correct order, move to the cylinder position using
the ← and → cursor keys and increase or decrease the number using the ↑ and ↓
cursor keys.

If the engine is a V engine with two banks of cylinders, enter the firing order for the A
bank. The system is able to calculate the B bank results correctly without further
information.

3-10
 Chapter 3 – Operation of Instrument

3.8 UTILITIES Screen (Normal Mode)

The UTILITIES screen is selected by pressing [UTIL]. Options are selected by using
the four cursor keys as in the SETUP screen. The format of the screen is shown
below.
UTILITIES Screen (Normal Mode)

MEASUREMENT MODE Selection

There are two measurement modes. The normal one for most users is AVERAGED
and readings under this setting are taken as an average over the number of
averages chosen in the set-up. The other option is NON AV X 10 and this selection
forces the instrument to take 10 readings on individual firing strokes. This uses 10
memories per cylinder per test (20 if a second sensor for Fuel Pressure etc. is used).
This can be used to help to find intermittent problems. Use the ← and → cursor keys
to make the selection.

READ PMAX Selection

This is a utility where the EPU can be used as a peak pressure gauge. To use this
option it is not necessary to have a crank pickup connected. Ensure the pressure
sensor is connected to an indicator cock and the cock fully opened and press [ENT]
to start the reading. The value for Pmax will update on the screen several times per
second. Note that for correct peak values to be recorded, the current scavenge
pressure must be entered in the MAIN screen.

3-11
 Chapter 3 – Operation of Instrument

CRANK SETUP Selection

This is used to check that the crank pickups are providing the correct signals to the
EPU. If the signals are not correct, the instrument will not be able to take a reliable
reading and may not take any reading at all. To initiate a check, first ensure the
pickups are in place and connected to the EPU. Press [ENT] and a screen will be
displayed describing the test to be carried out. This will either be for DUAL Pickups or
for TDC ONLY Pickup. To ensure the correct test is being made, the correct engine
set-up for the engine being tested must first be selected (see SETUP Selection).
Press [ENT] again to start the test. A screen as shown below will appear.

CRANK SETUP Screen

On TDC ONLY operation it is only necessary to ensure that the reported RPM is
correct and steady. On DUAL Pickup installations, the number of teeth reported
should be constant and although counted automatically, if the number is known it
must be correct. The engine speed must also be correct and steady.

TOOTH PK-PK is an indication of how much variation between teeth the pickup is
seeing. This should not exceed 10% (which on a flywheel with 60 teeth would be a
variation of 0.6° between successive teeth). Variation can be caused by speed
changes during each engine rev or by physical defects on the flywheel. The
DOCTOR is capable of handling large variations in speed and will track these very
well. If the variation exceeds the resolution being used, the DOCTOR will still
compensate but a lower resolution should be selected. As a guide, under 2%
variation will allow 0.1° resolution on a 60 to 80 tooth flywheel. If the variation
exceeds 10%, it is likely that the flywheel teeth are irregular and it is recommended to
change to a TDC ONLY configuration.

CLEAR MEMORY Selection

CLEAR MEMORY erases all data from the channel stores. Pressing [ENT] activates
the operation. A message: “ARE YOU SURE?” appears after which [ENT] has to be
pressed again. This is to avoid inadvertent erasing of data. Memories do not have to
be cleared of old data before new data is acquired - old data is simply overwritten.

3-12
 Chapter 3 – Operation of Instrument

EDIT ENGINE NAMES Selection

EDIT ENGINE NAMES enables the names of engines to be defined and edited. An
engine name can be up to 10 characters long. By selecting EDIT ENGINE NAMES
and pressing the [ENT] key, the screen below is displayed.

EDIT ENGINE NAMES Screen

Editing the name from a previous (or default) name is carried out by following the
instructions on the screen. The cursor keys enable characters to be changed
according to which character is being pointed to. The new name will appear on the
MAIN and SETUP screens for that SETUP NO. [ENT] moves on to a subsequent
engine, and [ESC] escapes back to the main UTILITIES screen. The facility to
define names enables the user to associate his own engine with the set-up
parameters he wishes to use.

SYSTEM RESET Selection

SYSTEM RESET is a master reset of the instrument and is normally only required if
the programme chips in the instrument have been changed (for example with
updated software). Pressing [ENT] will bring up an “ARE YOU SURE?” message,
pressing [ENT] again will start a large 10 second counter. At any time during the
count, the operation can be stopped by pressing any key. After following the on-
screen messages, all set-ups you may have made will be erased and set-up data will
be reset to default values. They can then be modified as desired. This operation
does not delete cylinder results, only the settings made in the SETUP and UTILITIES
screens are changed back to factory settings.

BATTERY LEVEL Selection

BATTERY LEVEL sets the voltage threshold on the main battery at which the BAT
low battery warning will be displayed. The message BAT appears on the top right
hand side of the screen if the battery is in a low discharge state (i.e. about 1-2 hours
remaining depending on the number of transducers connected). The threshold can
be varied to allow for ageing of the battery pack. The recommended level for setting
this is 5.9V. This selection can also be used to measure the battery voltage by
selecting higher numbers until the BAT warning appears. The threshold monitoring
can also be DISABLED so that no warning is given. Use the ← and → cursor keys to
make the selection.

3-13
 Chapter 3 – Operation of Instrument

DISPLAY MODE Selection

The screen can display in normal video or inverse video modes. Use the ← and →
cursor keys to make the selection.

SERIAL TRANSFER Selection

Serial transfer can either be SLOW or NORMAL. In some cases, a timing conflict
arises with certain computers and SLOW mode will normally overcome this. For the
vast majority of situations, use NORMAL for the fastest transfer possible. Use the ←
and → cursor keys to make the selection.

OPERATING MODE Selection

The two modes available are NORMAL and ADVANCED. Use the ← and → cursor
keys to make the selection. The advanced mode allows results to be calculated
directly in the EPU.

3-14
 Chapter 3 – Operation of Instrument

3.9 UTILITIES Screen (Advanced Mode)

With the ADVANCED mode selected, an additional menu item appears on the
UTLITIES screen. This allows the table of results which is presented after a reading
in advanced mode to be configured.

EDIT TABLE LAYOUT Selection

To edit the table, press the [ENT] key and the following edit table layout screen will
be shown.

Edit Table Layout Screen

Use the ← and → cursor keys to select the parameter you wish to enter in the next
column. Press [ENT] to select that parameter. Note that selecting clear first and then
pressing [ENT] will clear all columns. Pressing [ESC] saves the changes and takes
you back to the UTILITIES SCREEN.

3-15
 Chapter 3 – Operation of Instrument

3.10 VIEW Screen (Normal Mode)

The view screen appears after each reading or can be accessed at any time by
pressing the [VIEW] key. If there is no data in the memory selected in the main
screen, the message NO DATA FOR THIS MEMORY will be displayed.

A different memory may be selected from the MAIN screen by using the ← and →
cursor keys. Alternatively, from the VIEW screen repeatedly press the VIEW key to
select the fourth VIEW screen then use the ↑ and ↓ cursor keys to scroll through the
available results.

After data acquisition is complete, a graphic display of pressure versus angle is

shown. When a NON-AV X 10 reading has been taken, the display shows the first
measurement. Note that the value of Pmax is shown on the display screen. For
correct values of Pmax, the appropriate values of channel sensitivity and scavenge
pressure must have been entered in the SETUP and MAIN screens respectively. The
graphic display can be magnified up to a maximum of five steps by pressing the ↑
cursor key and reduced by pressing the ↓ cursor key.

VIEW Screen (Normal Mode)

When a graphic display is on the screen, pressing the [VIEW] key will display the
results of the measurement in numeric form.

Second VIEW Screen (Normal Mode)

3-16
 Chapter 3 – Operation of Instrument

Pressing the [VIEW] key a third time will provide the measurement conditions.

Third VIEW Screen (Normal Mode)

Pressing the [VIEW] key again will show a table of the available results with brief
details of the measurements. You can scroll through the results using the ↑ and ↓
cursor keys.
Fourth VIEW Screen (Normal Mode)

3-17
 Chapter 3 – Operation of Instrument

3.11 VIEW Screen (Advanced Mode)

In the advanced mode, the initiation of readings is the same – from the MAIN screen
just press the [GO] button. The same screen as in the normal mode is shown during
the measurement but the results are presented slightly differently. As with the
NORMAL mode, the view screens can be called up at any time by pressing the
[VIEW] key. Press the [VIEW] key again to move to the next VIEW SCREEN. There
are four screens showing the results as follows:

• A table of the results – the table as defined using the UTILITIES menu
selection for EDIT TABLE LAYOUT. You can scroll through the results using
the ↑ and ↓ cursor keys.

First VIEW Screen (Advanced Mode)

• Results for the memory selected in the first screen. This screen shows all the
available results for the memory – not just the ones selected for the table.

Second VIEW Screen (Advanced Mode)

3-18
 Chapter 3 – Operation of Instrument

• A graph of the result selected in the first screen. This presentation is the
same as the first screen in Normal Mode. The graphic display can be
magnified up to a maximum of five steps by pressing the ↑ cursor key and
reduced by pressing the ↓ cursor key.

Third VIEW Screen (Advanced Mode)

• The conditions under which the measurement was taken. This screen is the
same as the third screen in Normal Mode.

Fourth VIEW Screen (Advanced Mode)

3-19
 Chapter 3 – Operation of Instrument

Reviewing Data

Data can be reviewed any time except when a reading is in progress or downloading
is in progress. Press [VIEW] and the first VIEW screen will be displayed. The screen
you get will depend on whether you are operating in Normal or Advanced Mode. If a
memory contains no data, the message NO DATA FOR THIS MEMORY appears in
Normal Mode or <EMPTY> next to the memory numbers in the first screen in
Advanced Mode.

The graphic display can be magnified up to a maximum of five steps by pressing the
↑ cursor key and reduced by pressing the ↓ cursor key.

Downloading Data

Measurements are downloaded to the PC by connecting an RS232 cable between

the EPU and the PC and using the PC analysis software program to carry out the
transfer. It is not necessary to press any keys on the EPU - just ensure that it is
switched on.

Note that the EPU always assumes that the PC serial interface is set to 9600 baud,
and that the PC serial port set-up is the standard 9600,N,8,1. Flow control should be
set to None.

In the UTILITIES SCREEN, there is a selection for SERIAL TRANSFER and the
options are either NORMAL or SLOW. If you experience any problems with transfer
(as sometimes occur with older computers), try the SLOW selection.

3-20
 Chapter 4 – Operation of Installed Doctor Instruments

CHAPTER 4 - Operation of Installed Doctor

Instruments
4.1 General
Although the Installed Doctor instrument is no longer in production, this section is
included for those who own and operate such units.

Installed DOCTOR EPU units follow the same set-up and produce the same results
as portable units with a few exceptions. The principle differences are as follows:

• There is no battery in the unit. It is mains powered at all times.

• The set-up requires two additional parameters to be set. These appear on
Setup screen 3. The first is “ENGINE CHANNEL” and a number should be
entered here matching the way the system was installed. The second is
“PRESSURE VALID” and an acceptable low limit for cylinder pressure should
be set here. This prevents readings being taken with a closed indicator cock
for example.
• Readings are initiated from a small control box at each engine. This has a
large green GO button and an indicator LED. Pressing the GO button
automatically selects the correct engine on the EPU.
• The EPU is connected to the PC at all times.

4.2 System Layout

The following shows a typical layout for an installed DOCTOR system.

The JB-S2 has a connector for the pressure sensor, a large green “GO” button and
an indicating LED. The LED can show different colours and the meaning of the
colours is as follows:

• Green - The system is ready to take measurements.

• Amber - A Valid reading is being taken.

• Flashing Green - The reading currently being taken is out of range of the pre-
set Valid Range

• Red - There is a problem with the reading – check the EPU screen for details.

4-1
 Chapter 4 – Operation of Installed Doctor Instruments

4.3 Operating Sequence

Select the engine to be tested on the EPU and enter the scavenge pressure. If the
previously entered scavenge pressure is still valid, this step may be omitted.

If all results have been downloaded from the EPU, the memory should be cleared
from the UTILITIES menu.

Return to the MAIN screen.

Go to the engine and connect the pressure sensor to the control box.

Connect the Pressure Sensor to the first cylinder on the engine (always start at
cylinder 1 to keep things simple) and open the cock. If a Fuel reading is being taken
at the same time, connect that sensor to the fuel cock for No 1 cylinder.

Check that the indicator light is Green.

Press the GO button on the Control Box.

Watch the lights, a normal reading is indicated by the light turning to Amber and back
to Green.

If the light flashes Green, check that the indicator cock has been opened.

If the Red light comes on, check on the EPU screen for an explanation of the
problem. The most likely cause is incorrect pulses from the flywheel pickups.

If all is OK, move the sensor(s) to the next cylinder and press GO again.

Keep moving the sensor(s) and pressing GO till all cylinders have been read.

Go to the PC to initiate download of the readings. See the software Step-by-Step

guide for details.

4-2
 Chapter 5 – Fault Messages

CHAPTER 5 - Fault Messages

The Doctor instrument will give fault messages under certain conditions.

5.1 Crank Pickup Faults

If the crank pickup or pickups are not giving pulses when a reading is being taken,
the screen will freeze. This may happen during a measurement or during CRANK
SETUP.

In either case, pressing [ESC] will abort the reading. The following screen will
appear.

Press [ENT] to return to the MAIN screen.

5.2 Pressure Sensor Faults

If the instrument cannot detect a pressure sensor during normal reading, the
following screen will appear.

Press [ENT] to return to the MAIN screen.

5-1
 Chapter 5 – Fault Messages

If the instrument cannot detect a pressure sensor during normal reading, the
following screen will appear.

5-2
 Chapter 6 – Installation of Flywheel Pickups

CHAPTER 6 - Installation of Flywheel Pickups

6.1 Introduction
For correct operation of the Doctor system, a signal from the flywheel is required to
give engine speed. This signal is also used to provide instantaneous angular
position.

In single flywheel pickup arrangements, each rev is divided into small equal intervals.
For example, to achieve a resolution of 1°, each rev is divided by 360. This type of
pickup is referred to as TDC ONLY.

For higher accuracy on 2-stroke engines where the speed can vary slightly during
each rev, in addition to a TDC pickup, a second pickup senses the teeth. Each tooth
provides a secondary reference and tracks the speed of the flywheel more
accurately. This arrangement is referred to as DUAL.

There are two main types of pickup used. These are Optical and Inductive.

An optical pickup is used for maximum portability and is easily moved from engine to
engine. These use a signal reflected back by a piece of reflective tape attached to
the flywheel. With these pickups, the reference angle may need to be adjusted for
each set of readings if the pickup is positioned differently or if the reflective tape
needs to be replaced.

Inductive pickups are immune to oil and dirt and are used for longer term regular
measurement of engines. They sense the presence of metal and a bolt is normally
used as the TDC ONLY reference, while DUAL systems use a bolt for the TDC
reference and the flywheel teeth as the secondary reference. The permanent fixing of
these pickups ensures a consistent reference to flywheel position.

The pickups are powered by the Doctor instrument when connected and switched
ON. There is a LED on the rear of each pickup that illuminates when it is ON and
metal is within range.

6-1
 Chapter 6 – Installation of Flywheel Pickups

6.2 Optical Pickup Installation

The optical pickup has two main parts – the optical transmitter (OCP-2) and the
optical fibre (OFE-1). There is an alignment washer between the two parts; this is
glued in position by Icon to prevent it being lost.

Optical Transmitter

Optical Fibre

Alignment Washer

Flexible Armoured Optical Fibre

Tip with M6
Thread and Nut
Body is threaded
18mm X 1mm pitch

Flexible Armoured
Optical Fibre

The unit is normally kept assembled.

6-2
 Chapter 6 – Installation of Flywheel Pickups

Optical pickups should be firmly held in place with a bracket. The distance from the
optical fibre tip to the target tape should be as in the following table.

Optical Pickup Minimum Maximum

Configuration Separation Separation
With Optical Fibre 25mm 120mm
Extension
Without Optical Fibre 50mm 250mm
Extension

It is recommended that the optical fibre is always used as the installation is then not
sensitive to the orientation of the device. If only the main body of the optical pickup is
used, the two lenses in the end of the body should always be kept in the same
orientation relative to the flywheel for each set of readings.

In the installation above, the optic fibre is held in a small bracket that is clamped with
a G-clamp to the flywheel housing. The gap where the engine’s TDC pointer is
placed has been used in this case. Axial or radial installation will work equally well.
The reflective tape can be clearly seen on the flywheel, just under the end of the
optical fibre.

In some installations, engines have the optic fibre mounted permanently on each
engine (usually on the auxiliaries). In these cases, a bracket should be installed
instead of using the clamp in the picture above. The fibre and its connection are then
left in place and the main body of the optical pickup attached prior to taking a set of
readings.

6-3
 Chapter 6 – Installation of Flywheel Pickups

6.3 Inductive Pickup Installation

TDC ONLY pickup

The inductive pickups used have a threaded body and two securing nuts. The thread
pitch is 1mm on the pickups irrespective of diameter. A 12mm diameter pickup is
shown in the drawing below.

The pickup has a lamp on the rear of the body which will illuminate when the pickup
is connected to the Doctor instrument and when metal is within the sensing range.

For TDC ONLY operation, the pickup must sense a single marker on the flywheel.
This may be positioned either axially or radially.

The optimum sensing gaps and target sizes are shown in the table below.

Pickup Ideal Gap (range) Min Target Diameter Min Target Height
Size
18mm 3mm (2-8mm) 20mm 8mm
12mm 2mm (1-5mm) 15mm 5mm
8mm 1mm (0.5- 3mm) 12mm 3mm

The pickup should be mounted on a sturdy bracket, ideally attached to the engine
structure. In some cases it is acceptable to use the flywheel guard as a mount for the
pickup. Some examples of installations are shown below.

6-4
 Chapter 6 – Installation of Flywheel Pickups

Typical installation showing a

sturdy bracket attached to the
engine. The marker bolt in the
flywheel is not visible here.

In this example, the marker bolt in

the flywheel is clearly visible next
to the inductive pickup.

Here is an example of an
inductive pickup that has
been fitted directly to the
flywheel guard. This method
is often used on smaller
engines. The guard should be
of the type that is rigidly
attached to the engine.

6-5
 Chapter 6 – Installation of Flywheel Pickups

In this case, it was not

convenient to put a target
bolt in the flywheel so a
marker tab was attached
instead. Any metal
marker may be used; it
does not necessarily have
to be a bolt.

Shown below is a schematic, outlining the basic dimensions for a TDC ONLY axial
pickup installation using a 12mm pickup. For 18mm pickups please refer to the table
above.
Single bolt in flywheel.
The bolt head is larger in
Flywheel
diameter than the pickup.
Teeth Pickup
Pickup Length 50mm
Length 30mm
Inductive pickup
12mm dia shown.

Bracket made from

5mm strip steel (for example).

Flywheel
Gap 2mm (for 12mm pickup)
See table for details.

Bolt head to be clear of flywheel surface

by a minimum of 5mm (for 12mm pickup)

Notes:
1. The bracket should be solidly
mounted to the engine.
2. The marker bolt can be radially
or axially positioned (axial shown).
3. The angular position of the bolt
can be corrected for in the Doctor
software. It can be beneficial to use
a different angle on each engine.

6-6
 Chapter 6 – Installation of Flywheel Pickups

DUAL pickups

When DUAL pickups are used, one of the pickups senses the flywheel teeth, the
other senses a single marker on the flywheel. This single marker is normally a bolt
head of larger size than the pickup.

DUAL pickups are used to minimise the effect of small variations in speed during
each rev of the engine. By sensing each tooth position, the Doctor is able to track
these speed variations and compensate for the small changes in speed.

The Doctor automatically counts the flywheel teeth for you; there is no need to count
them.

Normally, 18mm diameter pickups are supplied for DUAL pickup installation. This
type of set-up is used mainly on 2-stroke engines.

The gap settings and target sizes required for the pickups are shown below:

Pickup Ideal Gap (range) Min Target diameter Min Target Height
Size
18mm 3mm (2-8mm) 20mm 8mm
12mm 2mm (1-5mm) 15mm 5mm

The pickups should be positioned at least 50mm apart to avoid the risk of cross talk
between them.

The flywheel teeth pitch should be at least 5 times the diameter of the pickup used.

Some examples of typical installations are shown below.

Here a single bracket supports both pickups.

6-7
 Chapter 6 – Installation of Flywheel Pickups

In this case, two brackets have been used, one for each pickup.

This installation used a single bracket that was split at the end to position the
pickups. The marker bolt can be seen screwed into the flywheel just above the TDC
(upper in picture) pickup.

6-8
 Chapter 6 – Installation of Flywheel Pickups

The tooth pickup can be either axial or radial.

The schematic below shows a typical installation of DUAL pickups using a single
bracket.

Gap 3mm (for 18mm pickup)

See table for details. Pickup Length 50mm
Pickup Length 30mm.
Flywheel Theeth Flywheel tooth pickup
18mm dia shown

Single bolt in flywheel. Notes:

The bolt head is larger in 1. The bracket should be solidly
diameter than the pickup. mounted to the engine. 2 separate
brackets may be used if more
convenient.
2. The marker bolt can be radially
Single marker pickup or axially positioned (axial shown).
18mm dia shown 3. The tooth pickup may be radially
or axially positioned.
4. The tooth surfaces at the pickup
Flywheel should be machined surfaces in
good condition.
3. The angular position of the bolt
Bracket made from can be corrected for in the Doctor
5mm strip steel (for example). software. It can be beneficial to use
a different angle on each engine.
Gap 3mm (for 18mm pickup)
See table for details.

Bolt head to be clear of flywheel surface

by a minimum of 8mm (for 18mm pickup)

6-9
 Chapter 6 – Installation of Flywheel Pickups

6.4 Troubleshooting the Crank Pickups

Inductive and optical pickups are fitted with LED’s which will operate when the pickup
is sensing its target. With the pickup(s) connected to the EPU and the EPU switched
on, the first test is with the engine stationary to ensure that the pickups are operating
and their LED is illuminated.

Once this has been checked, the next test is with the engine running and using the
CRANK SETUP function in the UTILITIES screen. The operation of this is described
in the section on the UTILITIES screen.

The most common faults found are:

TDC Only Operation

RPM is double expected. Two TDC markers on flywheel

RPM too low or unsteady. Unreliable signal – check gap, pickup and
marker.
RPM too high. Pickup too close to flywheel.

Dual Operation

RPM is double expected. Two TDC markers on flywheel.

RPM too low or unsteady. Unreliable signal – check gap, pickup and
marker.
RPM too high. Pickup too close to flywheel.
RPM steady but number of Pickup too far from flywheel teeth. Check that
teeth low and or unsteady. target diameter is machined and there is no
run-out on the flywheel.
RPM steady but number of Pickup too close to flywheel teeth. Check
teeth too high and /or target diameter is machined and free of burrs
unsteady. or dents.
Max tooth variation > 3% Teeth probably worn or damaged – move
and RPM and No of teeth pickup to a more uniform diameter on teeth or
steady. revert to TDC only operation.
RPM correct but tooth The gap between the tooth readings is
reading fails at higher insufficient. Move the tooth pickup to a larger
RPM’s. diameter where the gaps are larger or use a
smaller diameter pickup with a higher
response. See the section on Performance of
Inductive Pickups below.

6-10
 Chapter 6 – Installation of Flywheel Pickups

6.5 Performance of Inductive Pickups

Inductive pickups have a maximum frequency at which they can trigger. This is no
problem for TDC pickups but can become important on flywheel teeth.

The required frequency for an engine can be calculated by the following formula:

Frequency (kHz) = No of teeth on flywheel x RPM/60000

The frequency capabilities of the available pickups are:

Pickup Diameter Max Frequency

18mm 1kHz
12mm 2kHz
8mm 5kHz

6-11
Chapter 6 – Installation of Flywheel Pickups

6-12
 Chapter 7 – Electrical Connections

CHAPTER 7 - Electrical Connections

7.1 Channel Inputs
The DK-2 has a single pressure input channel and the DK-2/FV has twin channels.
The channel inputs are standard TNC connector styles. These are two wire
connectors i.e. power/signal and ground.

Each input is a standard ICP transducer type. The signal wire carries a constant
3.6mA which powers the transducer. The transducer outputs a voltage which moves
positively and negatively around a quiescent voltage. The quiescent voltage is
usually around 9-11V. The transducer power is derived from a 24V supply in the
EPU which means that large voltage swings can be accommodated.

The voltage derived from the transducer swings around the quiescent voltage. This
is then AC coupled to enable the signal to be referenced to ground. To avoid this AC
coupling causing offset errors when a dynamic signal is applied, a very long time
constant (tens of seconds) is used.

Any ICP transducer compatible with constant current power sources can be used.

Crank Interface

The two crank inputs accept CMOS/TTL (5V) logic inputs. The crank pickups
produce these types of signal. If an alternative encoder to the standard pickups is
used, then it must produce CMOS/TTL level pulses.

The pin-out of the crank connector is shown below.

Crank Pin-Out

7-1
 Chapter 7 – Electrical Connections

RS232

Only 3 wires are required on the RS232 cable, namely RX, TX and GND. The pin-
out is shown below.

RS232 Pin-Out

For connection to the 9-pin connector on a PC computer, a cable as shown below is

recommended.

EPU/PC RS232 Cable

RS232 Cable Connections

Power

The EPU can be powered from its internal rechargeable battery pack or from mains
power using the charger supplied. The charger can take any input voltage in the
range 100 to 240Vac and 50 or 60Hz. Three different types of power cord are
supplied, namely UK, US and Euro. These cover virtually any mains source
encountered in the world.

The DC output of the charger is rated at 9V, 3A. The connection is shown in the
diagram below.

If the charger supplied is lost, it is possible to use a supply as per the above rating
and connection to charge the instrument. The dc plug is a standard type, the outer
cylinder diameter being 5.5mm and the inner diameter being 2.5mm.

7-2
 Chapter 8 - Technical Specification

CHAPTER 8 - Technical Specification

Inputs

No. of Channels DK-2 1

DK-2/FV 2
Input Sensitivity Range 90dB
Channel Input (per channel) ICP 3.6mA self powered, two-wire
(24V nominal)
Input Voltage Range +/-5V
Transducer Time Constant 33 seconds (auto-zero at switch on)
Sampling Rate Variable to 8kHz

Crank Synchronisation

No. of Channels 2
Channel 1 Input Once-per-rev
Channel 2 Input N-per-rev (variable) (automatic count of N per
rev)
Channel 2 Multiplication Variable to x 255
Multiplier Function Digital, constant phase
Angular Resolution 2º,1°, 0.5°, 0.2°, 0.1°
Averages 1-100 engine cycles per cylinder

User Interface

Display Type High contrast, back-lit graphic LCD

Display Resolution 240 x 128 pixels
Keypad Type 16-way sealed rubber mat

Selections Menu driven, by inverse video

General

Weight DK-2 and DK-2/FV - 4.5 kgs approx.

Dimensions DK-2 and DK-2/FV - 35cm x 24cm x 15cm
approx.
Sealing IP67 lid closed, IP65 lid open
Serial Interface RS232, to 9600 Baud

Power

Type 9V external power supply or internal

rechargeable battery
Battery Recharge Time 2.5 hours approx.
Battery Charge Method Intelligent fast charge, reducing to trickle when
battery fully charged.
Battery Charge Duration 15 hrs with one transducer (approx.)
12 hrs with 2 transducers (approx.)
Mains Input 100-240V AC
50-60Hz

Specification is subject to change without notice.

8-1
Chapter 8 - Technical Specification

8-2