MAINTENANCE MANUAL

AHGM SERIES

CONTENTS

1. INTRODUCTION

2. SPECIFICATIONS
2.1 SYSTEM BLOCK DIAGRAM
2.2 PHYSICAL LAYOUT OF ELECTRICAL CONNECTION
2.3 GENERAL SPECIFICATIONS
2.4 INTERNAL SETTINGS AND CALIBRATION METHODS

3. TROUBLE SHOOTING
3.1 TROUBLE SHOOTING LOOP
3.2 PARTS AND COMPONENTS TROUBLE SHOOTING

4. ELECTRICAL CIRCUITRY
4.1 SCHEMATICS
4.2 PCB LAYOUT

5. BILL OF MATERIAL

6. APPENDIX

MARCH 2003 REV 2

Specifications and Fun ction Subject to Change without Notice

1
1. INTRODUCTION

The AHGM series is designed and programmed according to the OIML -76
R
Class III requirements.

This scale is sealed to preventunauthorized access to internal parts.

Ender users should be advised not to undertake any trouble shooting
except those listed on the operation manual.

This maintenance manual containsof certain information that may result

in fraudulent use. Do not release any part of this manual to any end
users or un-authorized persons.

The internal mini jumper should be so set to prevent un-authorized

settings or alternations.

Should a load cell has been replaced, make sure that the protection
devices are properly set.

After servicing, it is necessary to go throughall tests and procedures

to ensure the scale meets all the meteorological and approval
requirements.

Here are some features of the AHGM series

1. Designed to meet OIML-R76 class III requirements.

2. Zero Indicator.
3. Net Indicator.
4. Negative Value Indicator.
5. Auto Tare Function.
6. Power on Zero Function.
7. Manual Zero Function.
8. Extended Display Function.
9. Auto Power Saving Function.
10. Metric/Avoirdupois Conversion Function.
11. Low battery warning signal.
12. 2 points Calibration.
13. Mini jumper to prevent end-user calibration.
14. Optional EL backlights.
15. Optional RS232C interface.
16. Optional Rear Display
17. Built-in rechargeable battery operated.
18. Battery operating time: 200 hours plus after charged
.

2
2. SPECIFICATION
2.1 SYSTEM BLOCK DIAGRAM
LCD

LCD DRIVER INTERFACE

E+ CPU
LOAD E- A/D UNIT with ROM
CELL S+
S-
POWER SUPPLY: KEYBOARD
AC ADAPTOR (5 KEYS)
(9V/500mA)
RECHARGEABLE
BATTERY (6V 4Ah)

Description:
When a mass is placed on the platform, the load of the article is applied
to the load cell inside it.

The resistance to the excitation current in the strain gauge will then
changed and the analog output signal varies.
It is amplified and digitized continuously by the A/D converter into
a digital signal. Subsequently, the resulting count is processed and
managed by the CPU. The CPU refers to the instructions from the keyboard,
and then conveys the output data to LCD driver, which formats the data
into readout on the display panels.

3
2.2 PHYSICAL LAYOUT OF ELECTRICAL CONNECTION

LCD CN1

AGM-40-X
POWER BOARD
OPTIONAL REAR PISPLAY BOARD GM-20-X

DC JACK
LOAD CELL

RS-232 BOARD
RECHARGEABLE RS232C-1B1
BATTERY
6V 4Ah

MAIN BOARD

AGM-10-X J5

LCD J3

J4 E+

E-

S+

S- J2

MEMBRANE K/B

4
2.3 GENERAL SPECIFICATION

2.3.1 Overall View

5
2.3.2 Dimension:

Platter size¡ 250 x 215mm

Overall size¡ 250(W) x 285(D) x 105(H)mm

2.3.3 Model Specifications

Model Number Capacity (Max) Division (e)
AHGM-1500 1500g 0.5g
AHGM-3000 3000g 1g
AHGM-6000 6000g 2g
AHGM-15K 15kg 0.005kg
AHGM-30K 30kg 0.01kg
Approval Class III
Maximum Tare Range 1/3 Max -1e
Power on Zero Range ¡10% Max
Manual Zero Range ¡2% Max
Min. Load 20e
Operation 0o~40oC (32o~104oF),
Environment Non-condensed. R.H.¡ 85%
Power Consumption 0.5W (when charged)

2.3.4 Main Components Used

Microprocessors: SM8958
Crystal Oscillator: 11.0592MHz
Display Device: WTN Liquid Crystal Display

2.3.5 Analog Specification

- The maximum number of verification scale intervals will be:
n 3000 for class I I I instruments
- Power supply of 5 V DC;
- 16 bits serial digital output;
- Excitation power supply for the load cell is 5 V DC;
- Input impedance of the load cell is 350 ;
- The analog data processing unit is built in a closedmetal box.

6
2.4 CALIBRATION METHODS

AUTO CALIBRATION
a. Turn scale off
b. Press and hold MODE, then press ON/ZERO
c. Scale displays CAL._1
d. Press MODE for YES and scale will self calibrate zero point
before proceed to the first point calibration
e. Load the mass according to the display, normally the first
point is 1/3 of the full capacity
f. Press MODE when display is flashing
g. Scale displays CAL._2
h. Press MODE for YES or ON/ZERO to exit
i. Load the mass according to the display, normally the second
point is the full capacity
j. Press MODE when display is flashing to complete the calibration
procedures

7
3. TROUBLE SHOOTING
3.1 TROUBLE SHOOTING LOOP

POWER ON

NO DISPLAY DISPLAY RANDOM

FIGURE
COUNT DOWN?

CHECK POWER SUPPLY, CHECK CPU,LCD,

CPU,LCD,KEYBOARD OK LCD DRIVER IC

COUNTS AND SHOW ¡00000¡

THEN ZERO?

CHECK LOAD CELL,

OK A/D UNIT,OFFSET
VALUE

GHOST UNSTABLE
PROPER READOUT?

CHECK POWER CHECK PLATFORM

SUPPLY,LCD,LCD STOPPER,LOAD
DRIVER IC,R21,23 CELL,A/D UNIT,
OK BAD SOLDERING

CAN¡T REACH THE

INCORRECT FULL CAPACITY
CORRECT READOUT?

RE-CALIBRATE OK CHECK PLATFORM

THE SCALE STOPPER,LOAD
CELL,OFFSET
VALUE

NORMAL OPERATION

8
3.2 PARTS AND COMPONENTS TROUBLE SHOOTING
3.2.1 Power Supply Checking
3.2.1.1 Relevant parts:
Power Board (GM-20-X)
Q1 (C1061)
Q2 (C945)
R1 (1.2R 1/2W)
ZD1(ZENER 8.2V)
DC JACK
BATTERY(6V 4Ah)
Q1 R1
C1061 1/2W 1.2R

R2 Q2
J1 1/2W 100R C945
SCD-22 B1
W04 1A
MB
D1 SIP4 BAT
ZD1 1N4148 R3 1 2PIN
2 1
8.2V 15K 3 2
4
R5
1/4W 220R Q3
A733

L1
L-59EGW
R4
470R

Main Board (AGM-10-X)

Q1 (A1515)
Q2 (C945)
Q6 (A733)
U6(AIC 1722-5.0)

9
Description:
1) Power source: Rechargeable Battery 6V/4Ah or AC adaptor(9V,
500mA)

2) How Battery is charged completely?

The charging voltage is regulated by Q1 (C1061) and ZD1 (8.2V) for
about 7 volts.
The charging current will go down automatically when voltage reached.
Q2 (C945) and R1 (1.2R, 1/2W) provide Over-Current protection.

3) +5V power drives digital circuit system.

U6 (AIC 1722-5.0) is a 5volts Voltage Regulator.

4) +5V power drives analog circuit system.

U4 (NS2950A) is a 5volts Voltage Regulator.

4) Auto-off:
If the scale is set with 4_oFF or even under LO-BAT situation,
after fixed time interval, CPU will release a low potential signal
to draw down Q2, then Q1 cuts off, the scale will be shut down
immediately.

5) Low Power Detection:

The Q6(A733) is designed to detect the power level. When battery
power is less than 5.5V,the collector pole will become high potential,
then CPU will instruct LCD display to show LO-BAT symbol.

3.2.1.2 Input voltage: 5.5V or higher

Check and recharge battery if voltage is less than 5.5V.

3.2.1.3 System voltage (Vcc): 5V +/- 10%

Check that the system voltage is within 5V +/- 10%
a) less than 4.5V, the CPU may not work properly.
b) more than 6V, ghost will appear on LCD.

3.2.2 Platform Stopper Checking

The platform device shall not touch anything around itself during
operation. Check that the platform is not contacted with the upper
(no load) and/or lower (with load) stopper.

3.2.3 LCD Display Checking

3.2.3.1 Check that it is soldered and connected properly between LCD

and driver IC (PCF8576), driver IC (PCF8576) and CPU.

10
3.2.3.2 Check whether LCD is broken.

3.2.4 CPU Checking

3.2.4.1 Check that all pins are seated properly into the socket.

3.2.4.2 Check that the Crystal Oscillator works.

3.2.4.3 Check the RESET is normally low.

3.2.5 A/D Unit Checking

3.2.5.1 Check that the +5V powers are correctly fed to t

he
A/D unit.

3.2.5.2 Check that the signal output of loadcell is normal.

3.2.5.3 Check OP. Amplifiers & A/D Converter (AD7705).

When no error is found with the above checking procedures, the trouble
can be caused on the loadcell or the PCB itself. Replace a new one
could be better to identify the defective.
In this way, the readout of weight would be varied because of the output
voltage of loadcell and different span value, so re -calibration is
required after this replacement.

11
4. ELECTRICAL CIRCUITRY
4.1 SCHEMATICS

12
13
14
15
 16
1 2 3 4
D D
Q1 R1
C1061 1/2W 1.2R
R2 Q2
J1 1/2W 100R C945
SCD-22 B1
W04 1A
MB
D1 SIP4 BAT
C
ZD1 1N4148 R3 1 2PIN C
8.2V 2 1
15K 3 2
BATTERY 6V 10AH
4
R5
1/4W 220R Q3
A733
L1
L-59EGW
R4
470R
B B
Title
A A
G-SERIES CHARGING BOARD
Size Number Revision
A4 GM-20-2
Date: 1-Dec-2000 Sheet 1of 1
File: E:\GM20B.S01.sch Drawn By: BEN LEE
1 2 3 4
 4.2 PCB LAYOUT

AGM-10-1 TOP LAYER

AGM-10-1 BOTTOM LAYER

AGM-10-1 TOP OVERLAY

AGM-10-1 BOTTOM OVERLAY

17
AGM-40-1 TOP LAYER

AGM-40-1 BOTTOM LAYER

AGM-40-1 TOP OVERLAY

AGM-40-1 BOTTOM OVERLAY

18
5. BILL OF MATERIAL

STRUCTURE
Parts No. Description Specification Qty Remark__
E1AGM000010 P.C.B. KIT AGM-10-1 MAIN BOARD 1
E1AGM001000 P.C.B. KIT AGM-40-1 REAR BOARD 1
E1GSP010000 P.C.B. KIT GM-20-1 POWER BOARD 1
A0002030*** LOAD CELL C2G1 1
AHGM-1500 C2G1-3kg
AHGM-3000 C2G1-6kg
AHGM-6000 C2G1-10kg
AHGM-15K C2G1-20kg
AHGM-30K C2G1-35kg

A6010230950 ADAPTOR 230V/ 9V 500mA 1

C1GEC000000 PANEL PC G SERIES, 98*45.5*0.8mm 1
C1AHGM03000 OVERLAY AHGM SERIES 1
C1AHGM03099 REAR PANEL AHGM SERIES, REAR DISPLAY 1
A1205010210 BATTERY WIRE 21cm (BLACK) 1
A1205010212 BATTERY WIRE 21cm (RED) 1
A1600060400 RECHARGEABLE BATTERY GP4-6 6V 4AH 1
A5001000301 CABLE TIE CV-120S 3
A5005000090 BUBBLE LEVEL D14 (Dia. 14mm) 1
F0002GP0000 S/S PLATTER GP,NEC,NEP SERIES 1
F0003GSP100 ALUMINUM L/C SUPPORT GSP SERIES (C2X1 L/C) 1 UPPER
F0003GSP101 ALUMINUM L/C SUPPORT GSPSERIES (C2X1 L/C) 1 UNDER
G0001GSP000 PLASTIC CABINET, UNDER GSP SERIES (GRAY) 1
G0001GM0000 PLASTIC CABINET, UPPER GM SERIES(WHITE) 1
G0002GSP000 PLASTIC PLATTER GSP SERIES 1
G0004GSP000 RUBBER PAD CFR-190603 (GSP SERIES) 4
G0004MP0001 ADJUSTABLE FEET M SERIES 4
G0009EM0002 BATTERY CAP EM SERIES(GRAY) 1
Y0007GEC000 PACKING MATERIAL GEC SERIES 1
Z7GEC000000 DUST COVER G SERIES 1
A1202040401 WIRE ARRAY 4PIN 40cm, SINGLE HOUSING 1

A1007000002 FERRITE CORE TR-14.1*6.28*28.6mm 1

A1007000001 FERRITE CORE TR-16*9*28mm 1 LOADCELL

A1007000011 FERRITE CORE 19*6.5*32(CLAMP TYPE) 2 POWER,RS-232 TO MAIN BOARD

B0XM0000000 MEMBRANE K/B XM SERIES(OIML) 1

19
AGM-10-X MAINBOARD
E0AGM000010 P.C.B. AGM-10-1 1

A0102000281 L.C.D. UTN-G281JV 1 LCD1

A0201089582 I.C. SM8958C25P 1 U5

A0202093461 I.C. 93C46 1 U10

A0207017225 VOLTAGE REGULATOR I.C. AIC1722-50CZT 1 U6

A0208085760 I.C. PCF8576CT 1 U8

A0300000040 I.C. SOCKET 40 PIN 1 U5

A0401007330 TRANSISTOR A733 1 Q6

A0401009450 TRANSISTOR 2SC945 2 Q2,7

A0401015150 TRANSISTOR 2SA1515R(2SB1116K,A950Y) 2 Q1,8

A0501004148 DIODE 1N4148 1 D2

A0701106017 CAPACITOR (EC) 10uF/25V(SS TYPE) 2 C23,37

A0701107016 CAPACITOR (EC) 100uF/16V 2 C39,51

A0701226017 CAPACITOR (EC) 22£ F/16V (SS TYPE) 2 C24,38

A0701477016 CAPACITOR (EC) 470uF/16V 1 C18

A0730104050 CAPACITOR (MLC) 104Z 9 C25,27,28,32~34,49~50,52

A0740030050 CERAMIC CAPACITOR (CC) 30pf/50V(30) 2 C42,43

A0740101050 CERAMIC CAPACITOR (CC) 100pf/50V(101) 5 C19~21,29,48

A0804041503 METAL FILM RESISTOR 150K£ 1/4W 1 R49

A0804045003 METAL FILM RESISTOR 500K£ 1/4W 1 R48

A0805041101 CARBON FILM RESISTOR 100£ 1/4W 2 R17,18

A0805041102 CARBON FILM RESISTOR 1K£ 1/4W 2 R26,28

A0805041103 CARBON FILM RESISTOR 10K£ 1/4W 8 R19,20,22~24,27,29,43

A0805041153 CARBON FILM RESISTOR 15K£ 1/4W 1 R21

A0805041223 CARBON FILM RESISTOR 22K£ 1/4W 2 R47,50

A0805041272 CARBON FILM RESISTOR 2.7K£ 1/4W 2 R44,51

A0805041472 CARBON FILM RESISTOR 4.7K£ 1/4W 2 R40,45

A0805041473 CARBON FILM RESISTOR 47K£ 1/4W 1 R46

A0802010305 RESISTOR NETWORK 10K£ 5 PIN 2 NR8,9

A0901011040 CONNECTOR 4 PIN WAFER 90¢ 1 J2

A0907020240 CONNECTOR (PIN PLUG) 2 x 12 PIN 180¢ 1 J4

A0910000070 CONNECTOR (FPC) 7 PIN 180¢ 1 J5

A0910100110 SOCKET STRIPS SIP 1*11(FEMALE) 2 LCD1

A0907010030 CONNECTOR 1 * 3 PIN 180¢ 1 JP2

A0910111020 MINI JUMPER PITCH 2.54 1 JP2

A1100211059 CRYSTAL 11.0592MHZ 1 X1

20
A1500000004 BUZZER OBO-15210 1 BZ1

A/D SECTION
A0203077050 I.C. AD7705AN 1 U3

A0206000072 I.C OP177 2 U1-2

A0207029500 VOLTAGE REGULATOR I.C. AS2950AW 1 U4

A0702226016 CAPACITOR (TC) 22uF/16V(226) 1 C10

A0713105063 POLYESTER FILM CAPACITOR(MEF)1uF/63V (105) 1 C7

A0730104050 CAPACITOR (MLC) 104Z 10 C1-6,C8-9,C16-17

A0740047050 CERAMIC CAPACITOR (CC) 47pf/50V(47) 2 C11-12

A0740101050 CERAMIC CAPACITOR (CC) 100pf/50V(101) 3 C13-15

A0803041002 METAL FILM RESISTOR 10K£ 1/4W 2 R7-8

A0803041501 METAL FILM RESISTOR 1.5K£ 1/4W 1 R12

A0803043001 METAL FILM RESISTOR 3K£ 1/4W 1 R11

A0803041500 METAL FILM RESISTOR 150£ 1/4W 1 R9 (SPAN)

A0804044701 METAL FILM RESISTOR 4.7K£ 1/4W 4 R3-6

A0805041101 CARBON FILM RESISTOR 100£ 1/4W 3 R10,R13-14

A0805041103 CARBON FILM RESISTOR 10K£ 1/4W 1 R16

A0805041561 CARBON FILM RESISTOR 560£ 1/4W 1 R15

A1008000001 EMI FILTER DSS-306-55Y5S471M100 3 EMI1-3

A1100249152 CRYSTAL 4.9152MHZ 1 X2

F0015000012 PROTECTION BOX 7705-52-1 (UPPER) 1

F0015000013 PROTECTION BOX 7705-52-1 (UNDER) 1

Z0010000305 SCREW M3*6 2

AGM-40-1 REAR BOARD

E0AGM001000 P.C.B. AGM-40-1 1

A0102000281 L.C.D. UTN-G281JV 1 LCD1

A0910100110 SOCKET STRIPS SIP 1*11(FEMALE) 2 LCD1

A0907020240 CONNECTOR (PIN PLUG) 2 x 12 PIN 180¢ 1 J1

A0701107016 CAPACITOR (EC) 100uF/16V 1 C1

A0730104050 CAPACITOR (MLC) 104Z 1 C2

A0805041102 CARBON FILM RESISTOR 1K£ 1/4W 1 R1

A1203240350 FLAT CABLE 24PIN 35CM 1 J1

21
BACK LIGHT OPTION
A1400000009 BACK LIGHT 82*40mm 1 EL1

A1401005000 BACK LIGHT INVERTER 5V / 90c ¢ 1 IN1

RS232 OPTION
E1GEC100000 P.C.B. KIT RS232C-1B1 RS232 BOARD 1

A0901010040 CONNECTOR 4 PIN WAFER 1 J3

A1007000002 FERRITE CORE TR-14.1*6.28*28.6mm 1

A1202040401 WIRE ARRAY 4PIN 40cm, SINGLE HOUSING 1

22
6. APPENDIX

23
ITEM PART NAME DESCRIPTION QTY
1 PLASTIC CABINET, UPPER GM SERIES(WHITE) 1
2 PLASTIC CABINET, UNDER GSP SERIES (GRAY) 1
3 ALUMINUM L/C SUPPORT(UPPER) GSP SERIES (C2X1 L/C) 1
4 ALUMINUM L/C SUPPORT(UNDER) GSP SERIES (C2X1 L/C) 1
5 PLASTIC PLATTER GSP SERIES 1
6 ADJUSTABLE FEET M SERIES 4
7 BATTERY CAP EM SERIES(GRAY) 1
8 OVERLAY AHGM SERIES 1
9 REAR PANEL AHGM SERIES, REAR DISPLAY 1
10 LOAD CELL C2G1 1
AHGM-1500 C2G1-3kg
AHGM-3000 C2G1-6kg

AHGM-6000 C2G1-10kg

AHGM-15K C2G1-20kg

AHGM-30K C2G1-35kg
11 RUBBER PAD CFR-190603 (GSP SERIES) 4
12 PANEL PC G SERIES, 98*45.5*0.8mm 1
13 RECHARGEABLE BATTERY GP4-6 6V 4AH 1
14 S/S PLATTER GP,NEC,NEP SERIES 1
15 P.C.B. KIT AGM-10-1 MAIN BOARD 1
16 P.C.B. KIT AGM-40-1 REAR BOARD 1
17 P.C.B. KIT GM-20-1 POWER BOARD 1
18 FLAT CABLE 24PIN 35CM 1
19 WIRE ARRAY 4PIN 40cm, SINGLE HOUSING 1
20 BUBBLE LEVEL D14 (Dia. 14mm) 1
21 MEMBRANE K/B XM SERIES(OIML) 1

24
 APPRO VED NO. REV.

DRAWING NO.: AHGM-M-01-A 1

DWG. AHGM SERIES
NAME SEALING DIAGRAM

AHGM SERIES SEALING DIAGRAM

SEALING POSITION

25