SERVICE MANUAL

CHASSIS CTU-AA
1. Technical specifications

CHASSIS CTU - AA

Mains voltage : 220 - 240 V ± 10% AC; 50 Hz (±5%)

Power cons. at 220V~ : 35 W (14’’), 50W (20’’/21’’), 3W (Stand-By)
Aerial input impedance : 75 Ω - coax
Min. aerial input VHF : 30µV
Min. aerial input UHF : 40µV
Max. aerial input VHF/UHF : 180mV
Pull-in range colour sync. : ± 300Hz
Pull-in range horizontal sync. : ± 600 Hz
Pull-in range vertical sync. : ± 5 Hz
Picture tube range : 14'' / 20’’ / 21‘’

: Mono: 25∧ 1W (14’’), 16∧ 2W (20’’/21’’)

: Stereo : 2x16∧ 2x4W (21’’)+

TV Systems : PAL BG
: PAL I
: PAL BG / SECAM BG DK
: PAL BG I / SECAM BG L L'

Indications : On screen display (OSD) green and menu

: 1 LED (red in ON and blinking red in stand-by)

VCR programs : 99

Tuning and operating system : VST

UV1315A / IEC (VST) : VHFa: 48 - 168 MHz

: VHFb: 175 - 447 MHz
: UHF: 455 - 855 MHz

U1343A / IEC (VST) : UHF: 455 - 855 MHz

Local operating functions : Vol/Prog, +, -, contrast, colour, brightness and sharpness (and hue on program AV
with NTSC signal).

2. Connection facilities
Euroconector:

1 -
Audio R (0V5 RMS ó 1K ). 17 - CVBS
2 -
Audio R (0V2 - 2V RMS ò 10K ). 18 - CVBS
3 -
Audio L ( 0V5 RMS ó 1K ). 19 - CVBS ( 1Vpp 75W ).
4 -
Audio 20 - CVBS ( 1Vpp/75W ).
5 -
Blue 21 - Earthscreen.
6 -
Audio L (0V2 - 2V RMS ò 10K ).
7 -
Blue (0V7pp/75W ).
8 -
CVBS status 1 (0-2V int., 10-12V ext.).
9 -
Green
10 -
-
11 - Green (0V7pp/75W ).
12 - -
13 - Red Head phone:
14 - -
15 - Red (0V7pp/75W ). 8 to 600Ω. Mono : 25mW at 32Ω
16 - RGB status (0-V4 int.) (1-3V ext. 75W ). Stereo : 2x 6mW at 32Ω. 3,5mm ø.

3
3. Mechanical instructions

For the main carrier two service positions are possible (3.1).

A: For faultfinding on the component side of the main carrier.

B: For (de) soldering activities on the copper side of the main carrier.

Position A can be reached by first removing the mains cord from it's fixation, then loosen the carrier lips (1) and then pulling the
carrier panel (2) for approximately 10cm.

Position B can be reached from position A after disconnecting the degaussing cable. Put the carrier on the line transformer side.

Fig. 3.1

Fig. 3.2

4
4. Oscillograms

5
5. Print Board Layout
 +3V3A 7015 +3V3
8 1
E35 E32 D31

*
2628

*
*
*
- TV PROCESSOR - 3682 3684 3685 100N 7 7685 2
5K6 2K2 2K2
9682 1 64 24C04
- MICROCONTROLER - 6 3
STBY P1.3 SCL

SCL_2

SDA_2
- TXT - 5 4

2 63
3601 3602 P1.6/SCL SDA
+45 1K5 1K5

6602 2602 TP33 3 62

*
3603 3628 C30
HZT33 10U P1.7/SDA INT1 RC5
24K
100R
7605 * 3607*
3611* 3610 * 3604 * +3V3A
A1 3612 PMBT2369 +3V3
V_VARI 3606 * TP34 4 61 9656 +3V3
22K 5607
10K 10K 15K 150 TPMW VDDP

*
2622 10U

*
2611 2610 3605 10K 3618 * 2623
220N 220N 220K +3V3A 100N 100U
9618 1K5 5 60 3621 9621
D29
KEYBOARD ADC1 RESET POR
C2 RES

*
3656 * 3629 RES
1K
6. Electrical Diagram

+3V3A
TP17 22K 6 59 33P
MUTE P3.1/ADC1 XTAL_OUT
C3 2603 *
1679
12MHz
9613
9665 7 58 33P +3V3 +3V3
INT/EXT P3.2 XTAL_IN
C4 2604 * 9536
+3V3 +3V3
9664 8 57 9695
A5 +3V3 +3V3
VHFIII P3.3 OSCGND

9 56 5602 +3V3
VSSC/P VDDC
10U
*

2613 2600
100N RES
3663 10 55
LED P0.5 VPE
C6 270R

*
3675
*

2612 2601
1K3 100N 100U
11 54 M7:4 B28
A7
VHFI P0.6 VDDA GND_RGB
5601
TP28 10U

*
3614
47K 9017 12 53 3295 * M7:1 B27
A8 +8 +8 VSSA BO B_OUT
UHF
100R
7601 * TP29
9016
BC847
+8 +8 13 52

*
3615 3294 * M7:2 B26

*
RES 3613 SECPLL GO G_OUT
47K * 100R
2301 TP30
5301 220N
+8 10U 14 51 3293 * M7:3
VHFIII 7401 B25
A5 VP2 RO R_OUT
TDA8357J 100R 2290 * 470P
*

2303 2302
3410 * 3292 * M7:5 B24
TP16 9 100U 22N CUT_OFF
FBACK 15 50 1K 6496 *
2K7 A9
8 DECDIG CUT_OFF/VGUARD VGUARD
A9 LL4148 3496
*
*

VGUARD GUARD 2304 2299

*

3495 1K
9496 220N RES 10K
7
OUT_A 16 49 D24
9417 +45 6 PH2LF BCL BCL
M5:1
*

VFB 2305

*
*

2416 2298
5 2N2
3414 100N 100N
GND 3301 * 17 48 2293 * C23
TP15 75R
3415 9414 4 PH1LF B2/UIN B_EXT
3402 OUT_B 15K 100N
*

2306 2307
390R +12B 9416 3 1U 4N7
2403 Vcc 18 47
68N 2292 * C22

*
3416 2417 2 GND3 G2/YIN G_EXT
Vi_B 100N
M5:2 TP11 100N
1
Vi_A 19 46 2291 * C21
DECBG R2/VIN R_EXT
*

- FRAME - 100N
2309 2308

*
*
3411 2411 3406
2K 2N2 9434 100R 2U2 22N
20 45 3291 * C20
1%
6413 * 9435 AVL/EWD INSSW2 FB_EXT
3413 * 3407 100R
TP32
330K 100R
*
*

13V 3412 2412

9401 21 44
2K 2N2 C19
VDRB AUDOUT AUDIO_OUT
1%
E19
*

2367
1N2
9402 22 43
9061 VDRA NC
+5A
*

+5 TP21 2366
2001 1N2
-TUNER - 1001 100U 6 1015 23 42 2010 * C18
IFIN1 CVBS/Y CVBS_EXT
1 4 3014 * 100N
2002*

11 47R +8
1U2
5010

24 41 +8A
+8 10 2 5 3015 * 2032 5033
IFIN2 GND1 10U
47R 100U
*

3002 3
2K7
3 4 5 2 1 25 40
3003* 3341 * 2034 * 3034 * A16
UHF
VHFI

UHF IREF CVBSINT INT_CVBS

VHFIII

A8 100R 39K 1% 100R

+8 9004
*

- IF - 47N 3035
* E17
*

2090 100R SIF

2005
470N

RES
*

3004 26 39 3031 * +8C

3005

+5A 2340 +8
2K7 6020 VSC VP1 +8A
3026* RES 100N 180R 2036
*

VHFIII 2031 3030

*

3017 100N 7004 * 100U

A5 +8 100R 2K2 BC857 1R
* 3032 * 1032
*

2091 3020 180R 27 38 1K

150R
*

3006 RES TUNERAGC IFVO/SVO INT_CVBS

3000

2K7 0R05 3019 3022 * 7005

*
*
*

2006 2017 3018 2018 TP22 BC847 A16

3007* *
22N 47U 27K 10N
VHFI
*

A7 28 37 3023 * 5032 - VIDEO -

100R 9102 2021 * +8C
8U2
AUDEEM PLLIF 3033
*
*

2092 3008
390R 100N 1K
*

RES 4K7 2102

3027 1033
3010 * 29 36 100K 3028
*

V_VARI D15
DECSDEM EHT EHT
*
*

A1 220K
+8 3025
*

A1 2103 2106 2023

47N 22K
*

3103 35 2105
30 C14
1K2 GND2 AUDEXT AUDIO_EXT
9103
SC_AUDIOOUT TP10 2U2
C11
7104 * 31 34 3371 9371
BC847 D13
SNDPLL FBISO H_FLYBACK
+8 27K
3104 * 3372
*
*

3101 6372
2K7 22K 8V2
*

5K6 2111
*

32 33 9403 9404 D12

820P NC HOUT LINE_DRV
*

3102
*

1K2 2104 3373 *

4N7 +3V3
TP9
470R
3103
3102
3101
3035
3034
3033
3032
3031
3030
3028
3027
3026
3025
3023
3022
3020
3019
3018
3017
3015
3014
3010
3008
3007
3006
3005
3004
3003
3002
3000
2628
2623
2622
2613
2612
2611
2610
2604
2603
2602
2601
2600
2417
2416
2412
2411
2403
2367
2366
2340
2309
2308
2307
2306
2305
2304
2303
2302
2301
2299
2298
2293
2292
2291
2290
2111
2106
2105
2104
2103
2102
2092
2091
2090
2036
2034
2032
2031
2023
2021
2018
2017
2010
2006
2005
2002
2001
1679
1033
1032
1015
1001

L8
M8
M6
J2
J2
K1
K2
K2
K1
L2
L2
K9
L2
K3
K3
K7
K6
K6
K6
J5
I5
L9
K8
K9
K9
J8
K9
J9
J9
K8
A2
B2
B3
D3
E3
B9
B8
C2
C2
B8
E2
D2
H7
G7
I8
H8
H9
I6
I6
K5
H6
H6
G6
G6
G6
G6
F6
F6
F6
G3
G3
G2
H2
H2
F2
M6
L5
L2
M6
L6
L6
K8
K8
J8
K1
J3
J2
K3
L3
K2
K6
K7
I2
K7
J7
J6
I8
C3
K2
K2
J6
J7

9695
9682
9665
9664
9656
9621
9618
9613
9536
9496
9435
9434
9417
9416
9414
9404
9403
9402
9401
9371
9103
9102
9061
9017
9016
9004
7685
7605
7601
7401
7104
7015
7005
7004
6602
6496
6413
6372
6020
5607
5602
5601
5301
5033
5032
5010
3685
3684
3682
3675
3663
3656
3629
3628
3621
3618
3615
3614
3613
3612
3611
3610
3607
3606
3605
3604
3603
3602
3601
3496
3495
3416
3415
3414
3413
3412
3411
3410
3407
3406
3402
3373
3372
3371
3341
3301
3295
3294
3293
3292
3291
3104

D1
A6
C7
D7
B2
C1
C7
C1
D1
G7
H7
H7
G9
G7
G8
M2
M3
I6
I6
M2
L8
K6
I7
E6
F6
J1
A2
B7
E8
G7
L7
G4
K1
K2
B8
F2
H8
M2
K7
B2
D2
E2
F6
J1
K2
J6
A2
A3
A5
E8
E8
C6
C3
B2
C2
B6
F8
E8
F8
B9
B8
B8
B6
B7
B8
B8
B8
B9
B9
F2
G2
H8
G8
G9
H9
I8
H8
F7
H6
H6
G9
M2
M2
M3
J5
G6
E2
F2
F2
F2
H2
M7
6. Electrical Diagram
2202 B6
2204 D6
2208 E3
2237 E3
3202 C6
3203 C5
3205 E2 Pos Pal BG Pal I Pal BG Pal I Pos MONO MONO STEREO
3206 E3 Mono Mono Stereo Stereo 1W 3W 4W+4W
3207 C8
3214 C8 1015 G1963 J1952 G1984 J1981 1540 T630mA T1A T2.5A
3215 C6
3216 C5 1032 5.5 6.0 5.5 6.0 2187 220U 220U 1000U
FOCUS
D42 3217 D8
25KV 3220 D8 2540 680U 680U 1500U
D41 3221 D8

23
1M1
VG2 3226 D3 3189 -- -- 1R
COMPONENTS -

D40
51R L3
3228 D6
Pos Mono Stereo 6450 BYT42M BYT42M BYW32
- DISPLAY -

+200 3229 D5

TP20
L1:1 D39
3205 3236 D3
A1 YES -- 6540 BYT42M BYT42M BYV98

6230
BAV21
2208
5235 E3

10U
FOCUS
6201 B5

2237
C3 -- YES 7187 TDA8941P TDA8943SF TDA8944J

3236

2N2
1K5
6216 C5
VG2 6229 D5 C4 YES --
6230 F3

+200

3206

9230
1M

RES
1K5 7200 C6 C5 -- YES
VG1
9226
9226 D3
9230 F3
- RGB & DISPLAY

FF*
3226
FF C6 -- YES
5235 L1:4 D38
FF
AQUA E -- YES
FF
B

GR
RG

L1:3 D37
2102 3N3 33P Pos 14" 20"/21"
33 L6

1M1

2103 10U -- C1 YES --

AQUA

2105 2U2 -- C2 -- YES

2106 -- 22N 23 MINI NARROW
2194 100U -- 2445 -- 220P
3203

3216

3229
1K5

1K5

1K5

2196 -- 10N 2446 8N2 9N1

BAV21

BAV21

BAV21
6201

6216

6229
+200

+200

+200

2860 4N7 -- 2448 10U 47U

3186 -- 0R05 3189 -- 1R
* 3191 68R -- 3214 560R --
3202

3215

3228
100R

100R

100R

2204
560P

3196 -- 0R05 3217 560R --

3197 0R05 -- 3220 -- 560R
3198 0R05 -- 3221 -- 560R
2202
100N

3199 0R05 -- 3415 4R7 3R3

9

5
+200

3808 JMP -- 3416 4R7 3R6

TDA6107Q 6

3810 JMP -- 3444 5K6 2W 5K6 3W

7200

3856 -- 100K 3235 1R 0.3W 1R 0.5W

1

5538 JMP FERRITE 3457 27R 0.5W 47R PR01

9004 -- JMP 3460 7K5 6K2
A-D

3207 *

9143 JMP -- 3480 -- 1K

3214 *

3220 *

3221 *

3217 *
560R

9144 JMP -- 5445 LOT 14" LOT 20"

9151 JMP -- 5480 -- 57331
L2:2

L2:3

L2:4

L2:5
L2:1

9450 -- JMP 5500 CU15 CU15D3

9802 JMP -- 5525 SOPS 14" SOPS 20"
RGB_GND

CUT_OFF
G_OUT

R_OUT
B_OUT

9809 YES -- 9480 JMP --

A27

A26

A25

A28

A24
 A - E - F

C1 14" C2 20"/21" - SCART + AV -

9686 +8
+3V3 +3V3
VIDEO
3877 +8
RC5 7875
A30 1685E 9685 1685 BC847

*
6849

*
21
3661 * IN

*
3661E
1 1K 1
3874 * RES
1K INT_CVBS 2876

20
2 2 A16 10U
6. Electrical Diagram

3664E * 3664 * CVBS_EXT

A18

19
3 3 3875 *
*

+3V3 100R +3V3 100R 3865

2685E 2685 +8
TSOP1836SS3V TSOP1836SS3V 75R

18
100U 100U 68R

*
3876
470R
*

17
9684 6848
GND GND 16 RES
+3V3 +3V3
FB_EXT
A20
15
6663E 6663 3845 * *3891
*

3858
R_EXT
B4_4534 B4_4534 A21 75R
14

100R
LED
A6 9687
75R

3855 *
13

6857 * 9857 6855 * 6856 *

+8
+8
12

RES RES RES

11

3843 *
*

G_EXT 3881
A22 10K
10

100R
75R

3879 * 7876 *
9

6853 * 6854 *
3853 *

26 47K INT/EXT
A2 A4
KEYBOARD MENU
8

RES RES
*
*

3880 BC847 3883

*
3665 5K6 10K
7

680R 3841 *
25 B_EXT
6

A23 100R 3852 *

P- 6851 * 6852 * AUDIO_EXT_R
75R

3851*
5

RES RES * 5K6 E43

*
3667
1K3
*

24 2856
2852

4
220P
*

RES 3810
3854 *
100K

P+ SC_AUDIOOUT 3860 *
A11
3

9809 220R *
SC_AUDIO_OUT_L
2

E46
2850
220P

3850 *
*

2860 AUDIO_EXT_L
1

E44
3808*

5K6
43

AUDIO
*

2859
*
3856 *

9169 C3 2857 RES

HEADPH_GND 220P
3864 *
E47 SC_AUDIO_OUT_R

*
3191 E45 220R
IN
9802
*

2194 42 2854 * 2858

1
RES 220P

*
2196 2192 *
C52 9168 10N 3
HPH_MONO 3893*
3197 * GND GND
11 AUDIO_EXT
9166
*

HPH_L 3198 A14

*
3199
E49 10
9167 3196 * 2
HPH_R/SPKSW
E48
C48

- AMPLIFIER - TP35
C4

C6 7187C
TDA8944J
48
7187B
TDA8943SF
3194 * 54
HPH_R/SPKSW OUT2+
E48 RES NC
*

2154 17 9
C48 7187 +11B 100N +11B
9143 VCC2
3193 * TDA8941P
HPH_MONO 16
1 8 GND2
*

C52 +11B VCC GND 3154 GND

*

3171 82R 15 8
9113 9114 3184 * 2181 * 10K OUT2-
AUDIO_OUT
A19 0R05 14
220N 2 7 NC
C19 OUT+ OUT- MODE
*

MAIN_R 3183 13 7
*

2197
*

C50 RES 3170 IN2+

RES
12
C5 3 6 SVR
6147 * IN+ SVR SVR
9147 2147 LL4148 2182 11 6
7140 * 10U MODE
+5B 10U BC847 3145 * 10
*

3140 4 5
*

3147 IN2-
*

22K 3142 MODE IN- IN-

100K
10K 10K 9 5
*

2179 2193 *
*

2195
3141* 220N IN1-
1N5
*

MUTE 7141 * 2183 8

A3 9140 10K 220N 1N5
BC847 NC
IN+
*2184 7 4
3186 *
MAIN_L IN1+
E51 9144 220N 6
*

3185 NC
RES OUT+
5 3
55
OUT1+
2155 +11B 4
9151 100N VCC1
VCC
*

3 2
3189
*

3155 GND1
82R 2
OUT1-
9170 OUT-
3190 +11B +11B 1 1
+11A +11B 9181
+11B +11B
*

2187 2190
1000U 220N
6663
6147
3893
3891
3883
3881
3880
3879
3877
3876
3875
3874
3865
3864
3860
3858
3856
3855
3854
3853
3852
3851
3850
3845
3843
3841
3810
3808
3667
3665
3664
3664
3661
3661
3199
3198
3197
3196
3194
3193
3191
3190
3189
3186
3185
3184
3183
3171
3170
3155
3154
3147
3145
3142
3141
3140
2876
2860
2859
2858
2857
2856
2854
2852
2850
2685
2685
2197
2196
2195
2194
2193
2192
2190
2187
2184
2183
2182
2181
2179
2155
2154
2147
1685
1685

D6
K9
G3
D2
E1
E1
E2
E2
B4
C4
C4
C5
C2
G4
F4
D3
F2
D3
F2
E3
E2
E3
F2
D5
E5
E5
F2
F3
F8
E8
C9
C7
C9
C7
H7
H7
G7
H7
J8
J8
G8
M8
M8
L8
L7
J7
J7
J4
K4
M3
J3
K9
K7
K8
K8
K8
C4
F4
F2
G4
G4
F2
G4
F3
F3
C9
C7
K4
G7
K3
G8
K3
G7
M8
M8
L3
K3
K5
J7
K4
L3
J3
K9
C8
C6

9857
9809
9802
9687
9686
9685
9684
9181
9170
9169
9168
9167
9166
9151
9147
9144
9143
9140
9114
9113
7876
7875
7187
7187
7141
7140
6857
6856
6855
6854
6853
6852
6851
6849
6848
6663

D5
F4
G2
D7
B7
B7
C7
M6
M6
G8
G8
H8
H8
L5
K9
L5
J5
K9
J8
J8
E2
C4
K3
K6
K8
K8
D5
D4
D4
E4
E4
F4
F4
C2
C2
D8
 E
- LINE - 3457
2458
5445
10N
25KV B41
5447 1
+101.5 11
2449 47U
2448 VG2 B40
RES 10N
2
3455 3456 FOCUS B42
H_FLYBACK
A13 100K 100K 9480
+8
6. Electrical Diagram

2451 5480 M5:3 M5:6

3460 A15
10U 3480 EHT
8
2450 3462 * 6463
3451 9464 A24
470N 6451 BCL
33K BYT42M TP14
12K 1N4148
2460
TP12 TP13 47N 2462
7445 4U7
3444 2445
+101.5

6447
2446
5K6 3W

*
2444 3 3445

BYD33M
2 BUT11AF
47N 47R TP38
5441
6452 3452
3470
1 4 6470 4R7 +45
6 BYT42M 1R
3440 * 7 2453
7440 2442 BYT42M 22U 9450
100R 2440 * 5440 2470
LINE_DRV 560P 10U +12
3
A12 1U 22U TP37

*
*
*
6440 3441 BF422 3442 4R7
LL4148 10K 5K6 3235 3450 6450 3453 7478
9 5 BC337
+8
1R BYT42M 2467
2454 3478 * 220U
10 4 5449
220U
3238 47U 390R
*

TP40 6474
C8V2
6449
*

3474
+12B
9479

56R
3449 BYT42M

M6:1
M6:4
M6:3

1R 2455
3479
470U TP39
390R 1/2W

+5
7479
BC337
3475 *
+8
470R
*

6479
FF
FF

+200

C5V6 2%
B39 B38 B37

2506
DEGAUSS
22 M2:1 M2:2 3N3
9503 1500
2534
9504
M1:2 T 2 A H RES TP1 5525 +101.5
4 5500 3 RES
6530 3530
6504

2N2
1N4007

5534
2504
6505

2500
3501 +101.5A
470N FERRITE
9501

PTC BYV95C 2530 4R7 PR03

7
2 1 2507 47U 3572
2N2

2505 8 TP6
2502
6502
6503

RES
1N4007 1N4007

68U
1N4007

9575 3541 RES

M1:1
3527
270K

KA5Q0765RT 7514 +11 +3V3

3504 10 7575
10M 3571 100R * 2561
9 BC337
560R 22U TP7
2562
100N

TP5
5533
SYNC
FB
VCC
GND
DRAIN
3528
270K

FERRITE
*
*

5 4 3 2 1 3570 6571
*

3573
12 47R 0R05 RES
2510
1N 6570 * POR
*
6525 6523 3V3 A29
7571
*

BAV21 BAV21 3575

*

- POWER SUPPLY - 3576 BC847 RES

180R
2514 3525 +11
47U TP2 2515
1 2532 470P
100U 4 1540 5538
TP3 10R +11A
6540
5
6511 3522 2540 FERRITE
5532
+11 FERRITE 9542
2 TP8
1N4148 1K2
3526 6524 3
2524
470R 1N4148 3539
3N3
TP4 3535 270R
+101.5 +11
9506 1K 2533
100U
*

6521 3542 2531 3531

*

7515 3533
*

RES 3511 1K RES

*

2527 180K 22K

3K9 TCET1103G
*

2528 47N
RES 3540 3534
RES 47K
2539 * 7572 *
*

22N 3536
39K 6531 9572 BC847 3537
7533 5K6 A31
KA431LZ STBY
*

3519 1N4148
9505 4K7
*

TP18 TP19 3532

10K
3571
3570
3542
3541
3540
3539
3537
3536
3535
3534
3533
3532
3531
3530
3528
3527
3526
3525
3522
3519
3511
3504
3501
3480
3479
3478
3475
3474
3470
3462
3460
3457
3456
3455
3453
3452
3451
3450
3449
3445
3444
3442
3441
3440
3238
3235
2562
2561
2540
2539
2534
2533
2532
2531
2530
2528
2527
2524
2515
2514
2510
2507
2506
2505
2504
2503
2502
2500
2470
2467
2462
2460
2458
2455
2454
2453
2451
2450
2449
2448
2446
2445
2444
2442
2440
2408
1540
1500

I3
J3
K4
I3
L3
K4
L1
L3
K4
L3
L2
L2
L3
H2
I5
I5
K6
J5
K5
L3
L5
I9
I7
C6
F2
E2
G2
F2
D4
C2
C3
B4
C6
C7
E2
D3
C6
E3
F3
D5
D7
E6
E7
E8
E4
E4
I2
I2
K2
L4
H3
K3
J3
L3
I3
L6
L6
K6
J5
J7
J6
I5
H4
I5
H6
H7
I6
H8
D5
E1
C2
C3
B4
F3
E2
D3
C6
C7
B5
B5
D4
D5
D7
E6
E8
B7
K3
H8

9575
9572
9542
9506
9505
9504
9503
9501
9480
9479
9464
9450
7575
7572
7571
7533
7515
7514
7479
7478
7445
7440
6571
6570
6540
6531
6530
6525
6524
6523
6521
6511
6505
6504
6503
6502
6479
6474
6470
6463
6452
6451
6450
6449
6447
6440
5538
5534
5533
5532
5525
5500
5480
5449
5447
5445
5441
5440
3576
3575
3573
3572

I4
L2
K2
K5
L7
H2
H9
H7
C6
F2
C1
E2
I3
L2
J3
L4
L4
J7
F2
E2
D5
E6
J3
J3
K3
L3
H3
J5
K5
J5
K6
K6
H6
H6
I6
I6
G2
E2
D5
C2
D3
C6
E3
F3
D4
E7
K2
H4
J6
K3
J4
H8
C6
E3
B4
D4
D6
E8
J3
J3
J3
I3
 7701 TDA9875A

- STEREO - 1 64 +5B
*3757
PCLK Vddd2
1R

*
2777
470N
2 63
NICAM LOR
A - C
3 62
ADDR1 LOL
3748 * TP25
+5B
3K3
A32 9728 3750 * 4 61
SCL_2 SCL MOL MAIN_L
100R C51

*
3749 * 2775 TP26
+5B 10N
3K3 TP27 5 60
A35 9727 3751 *
SDA_2 SDA MOR MAIN_R
100R C50

*
2773
10N
6. Electrical Diagram

TP31 6 59 +11B
3770 * +5C
Vssa1 Vdda +12
2R2

*
2772
470N

*
3771
18K 7781
7 58 2771 * 0R05
Vdec1 AUXOL 3780 * 2799

*
2770 2U2 HPH_L
BC337
*
10N 3772

2750
470N
100U C49
33K
*

8 57 3775
3752 * 2769 * 330R 1/4W
Iref AUXOR +11B
10K

*
2768 2U2 +12
10N
*

3769
9 56 18K 7780
P1 Vssa3 0R05
3781 * 2798
HPH_R/SPKSW
*

3774 BC337
33K 100U C48
*

10 55 3773
SIF2 PCAPL 330R 1/4W
*

2767
10N
11 54
Vref1 PCAPR HEADPH_GND
*

2766 9780 C47

*
2751 10N
100N
A17
9740 2740 * 2742 * 12 53
SIF SIF1 Vref3
27P 120P 2765
47U
5741
22U TP24

*
3741 13 52
6K8 ADDR2 SCOL2

*
2741
180P 14 51
Vssd1 SCOR2

3759* *3753 5753 * 15 50

+5B Vddd1 Vssa4
1R FERRITE

*
2753
470N
16 49
CRESET Vssd2

*
2754
1U
17 48 2764 * C46
Vssd4 SCOL1 SC_AUDIO_OUT_L
*

2763 2U2
470P
18 47 2762 * C45
XTALI SCOR1 SC_AUDIO_OUT_R
*

2761 2U2
1750 470P
24.576MHz 19 46
XTALO Vref2
2760
47U
20 45
P2 i.c. +12A

3702 TP41
21 44 +12 9701 9702 390R 1/2W
SYSCLK i.c. 9704 5702
+5B
JMP
3704 7702
BC635 9703
22 43 +5C
SCK Vssa2 10R
2702
47U
3703 *
23 42
WS i.c. 750R
*

6702
24 41 C5V6 2%
SDO2 i.c.

25 40
SDO1 Vref(n)
2759
26 39 47U
SDI2 Vref(p)
*

3756
270R
27 38
SDI1 Vdec2
*

2758
28 37 470N
TEST1 SCIL2

A19 3758 * 2755 * 29 36

AUDIO_OUT MONOIN SCIR2
C19 RES RES

30 35
TEST2 Vssd3

31 34 3755 * 2757 *
9710 C44
EXTIR SCIL1 AUDIO_EXT_L
GND GND 15K 330N

32 33 3754 * 2756 *
C43
EXTIL SCIR1 AUDIO_EXT_R
15K 330N
9780
9740
9728
9727
9710
9704
9703
9702
9701
7781
7780
7702
7701
6702
5753
5741
5702
3781
3780
3775
3774
3773
3772
3771
3770
3769
3759
3758
3757
3756
3755
3754
3753
3752
3751
3750
3749
3748
3741
3704
3703
3702
2799
2798
2777
2775
2773
2772
2771
2770
2769
2768
2767
2766
2765
2764
2763
2762
2761
2760
2759
2758
2757
2756
2755
2754
2753
2751
2750
2742
2741
2740
2702
1750

E2
E9
B8
C8
M8
I2
I2
I3
I3
C3
D3
I2
G5
J2
F7
F8
I1
D2
C2
D2
D3
D2
D3
C3
C3
D3
F8
L8
A3
K4
M3
M3
F7
D7
C8
B8
B8
B8
F8
I3
I3
I2
C2
D2
A4
B4
C4
C4
C3
C4
D3
D4
E4
E4
E4
G3
G4
H3
H4
H4
J4
K4
M3
M3
L7
G7
G7
E7
C7
E8
F8
E8
I2
H7
7.- CIRCUIT DESCRIPTION
7.1 SMALL SIGNAL &MICROCONTROLLER/TEXT(Diagram A)
The small signal is processed by IC 7015. This IC called Ultimate One Chip ( UOC ) also has an embedded
microcontroller.
The CTU-AA chassis is designed to accept 2 different ICs in the position 7015, TDA9350 for TXT models and
TDA9380 for no TXT. The associated circuitry is the same.
The small signal part includes IF detection, video processing, chroma decoder, RGB , sync processor and sound
decoder (mono sets). It is fully controlled by the embedded microcontroller.
The microcontroller contains an specific program that assures all the functions of the appliance, including 2 menus,
one to control the set (see Instructions Manual) and another for Service Mode (see Service Instruct. chapter 8.).
For stereo models sound decoder (IC 7101) is controlled also for IC 7015 by I2C bus.
The IC for TXT sets (TDA9350) contains a teletext decoder, including the following functions: TXT on/off, reveal,
freeze, temporary cancellation, clock, subcode, zoom, index, flof, page +/-, X/26 and 8/30 packet decoding (station
identification and start-up page).

Fig. 7.1 TDA 93XX block diagram

7.1.1 IF detection
IF detection is intercarrier type, that means sound and picture are detected in the same circuit (PIF).
- IF amplifier (pins 23, 24): The IF signal coming from pin 11 of the tuner (1001) is filtered by the IF SAW filter (1015)
and applied to IF amplifier of IC7015 by means of pin 23 and 24 input. The IF bandpass characteristic is determined
by the SAW (Surface Acoustic Wave) filter.
- PLL demodulator ( pins 37, 58, 59): The IF-signal is demodulated with the help of a PLL detector, which one is used
to regenerate the IF reference signal. Reference signal is determined by the PLL loopfilter pin 37 and calibrated by
microcontroller x-tal ( pins 58, 59). It is alignment free.
Demodulation is achieved by multiplying reference signal with the incoming IF-signal.
- AGC (pin 27): The IF AGC time constant is internally fixed. The tuner AGC voltage (pin 27) is applied to pin 1 of the
tuner and adjusted by microcontroller (see chap. 8.4).
- Video output (pin 38) : This baseband CVBS signal with 2.5Vpp (sync inclusive) of nominal amplitude, contains the
FM intercarrier sound signal. Sound is filtered out by a ceramic trap (1032 or 1033) which frequency can be different
depending on the system: 5.5 MHz for Pal BG and 6.0 MHz for Pal I.

7.1.2 Sound processor

Mono sets:
- FM demodulation (pins 31, 29): FM sound is filtered from CVBS (pin 38) by a loopfilter (pin 31) and
demodulated. Decoupling sound demodulator is made by a capacitor on pin 29.
- De-emphasis and audio out (pin 28): De-emphasis is made by C2102 at pin 28. The signal at this pin is drived
to the euroconnector sound output (see Diagram C) by transistor 7104 .
- External audio in (pin 35): External audio proceeding of pins 2,6 of euroconnector is applied to this pin.
Selection between internal or external is done by an internal switching controlled by I2C (see INT/EXT, chapter
7.6).
- Audio out (pin 44): After a volume control (by I2C), this output is drived to the input IN+ of the final sound
amplifier IC7187 (Diagram C).
Stereo sets:
SIF signal (pin 38): Video signal containing sound signal is drived to sound stereo processor IC7101 (see chapter
7.6 and diagram E)

7.1.3 Video processing

- Video switches (pins 40, 42): The internal CVBS signal proceeding of pin 38 is now fed to pin 40 of 7015. External
CVBS proceeding from pin 20 of Euroconnector is present on pin 42 of 7015. The IC switches between internal and
external are controlled by I2C bus (see INT/EXT, chapter 7.1.8).
The selected CVBS signal is internally supplied to the synchronization , teletext acquisition circuits and the video
identification circuit for IF ident.
- Luminance processor: CVBS is also internally applied to luminance processor, which is composed of chrominance
trap filter, luminance delay line and peaking circuits. Sharpness control modifies peaking by I2C.

7.1.4 Chroma processing

This circuit is an internal (no pins associated) automatic decoder for Pal and NTSC systems commanded by I2C bus.
- ACC and chroma filter: Video signal coming from video switches is supplied to PAL/NTSC chroma bandpass filter via
a variable gain amplifier which is controlled by ACC and ACL detection circuits.
The dynamic range of the ACC is 26dB and detects only the burst amplitude. The ACL is a chroma amplitude detector
and is active when the chroma/burst ratio exceeds approximately 3. It ensures that CVBS signal to chroma bandpass
filter is limited for large.
- PLL/DCO: Chroma PLL is integrated and it operates during the burstkey period; the DCO (digital controlled oscillator)
generates a subcarrier signal Fsc in phaselock with the incoming burst signal. The reference signal for the DCO
(Fref.) is derived from the crystal oscillator (1679). Different colour frequencies are internally switched by I²C. The hue
control rotates the DCO reference phases (H0, H90) from -40 to 40 degrees for NTSC signal via I²C bus.
- PAL/NTSC demodulation: The 0ª & 90ª signals are supplied to the burst demodulator circuits to obtain (B-Y) and
(R-Y) respectively. Chroma delay lines used in demodulators are internal.

7.1.5 RGB processor

- External RGB inputs (pins 46, 47, 48): RGB inputs coming from euroconnector (see diagram C), are AC coupled
(C2291/92/93) and converted internally in YUV signals. Then are switched with internal YUV (YUV SWITCH) by fast
blanking.
- Fast blanking external (pin 45): When fast blanking is high external RGB is displayed, only if TV is in external AV
(program 0). Fast blanking can switch signals for full screen (by a DC voltage) or for a part of the screen (by a pulse
voltage).
- Matrix: After switching, YUV signals are converted to R-Y, G-Y and B-Y in the internal MATRIX circuit. Saturation
control is received by I2C bus.
- Black stretcher: Internally the luminance signal is connected to the YUV select circuit and via the input clamps it is
supplied to the black stretcher. The black stretcher circuit, fully integrated, extends the grey signal level . This
extension is dependent upon the difference between actual black level and the darkest part of the incoming video.
RGB adder: RGB signals are obtained in this circuit by adding R-Y, G-Y and B-Y proceeding from matrix and Y
proceeding from black stretcher.
- RGB OSD: RGB inputs for OSD and TXT are internally inserted to RGB signals. Fast blanking used is also internal.
45).
- Beam current limiter (pin 49): The beam current limiter circuit functions as an average beam current limiter (BCL) as
well as peak white limiter (PWL). Both functions reduce the contrast and brightness of RGB signals.
Contrast reduction begins when Vpin 49 < 3.1V and brightness reduction begins when Vpin 49 < 1.8V.
BCL: Average beam current present at pin8 of 5445 (Diagram D) is feedback to pin 49. When beam current is high,
voltage of C2462 is lower, D6462 conducts and Vpin 49 decreases.
PWL: This circuit is an internal detection circuit, which comes into action if the difference between measurement DC
level and white level exceeds approximately 2.6V. Then a current of 200µA is internally produced to discharge 2298
and Vpin 49 decreases.
- RGB output circuit (pins 51, 52, 53): RGB outputs are drived to RGB amplifier (Diagram B).
- Continuous Cathode Calibration (CCC) (pin 50): This circuit is an auto-tuning loop which stabilizes the black level
(offset) as well as the cathode drive level (gain) of each gun. Pulses in 3 consecutive lines R, G and B (pins 51, 52,
53) at the end of frame blanking are used on alternating fields, one field for black level, following for cathode drive
level.
Cathode currents of 8mA for black level and 20mA for cathode drive level are stabilized. Cathode current is present at
pin5 of IC7200 (Diagram B) and measured on pin 50. RGB outputs are adapted to keep cathode currents measured,
for example when VG2 voltage is adjusted, DC level of RGB outputs is automatically corrected.
- Warm-up detection circuit (pin 50): At the start up a DC voltage of 2.5V is present in the RGB outputs (pins 51, 52,
53). As soon as beam current is detected on pin 50, RGB circuit starts in normal operation. If RGB circuit is damaged
or grid 2 is low, the RGB circuit could not start (black picture) due to current is not detected.

7.1.6 Horizontal synchro

- Start up: The horizontal oscillator starts is commanded by microcontroller. During start up circuit provides a softer
operating horizontal output with a higher frequency.
- Hor. sync. separator: Fully integrated sync. separator with a low pass filter, slicing level at 50% of the synchronized
pulse amplitude.
- Horizontal Phi 1 detector (pin 17): This circuit locks the internal line frequency reference on the CVBS input signal. It
is composed of a phase comparator and an internal VCO of 25MHz (1600*15625). The free running frequency is
stabilized using the 12 MHz reference of the X-tal oscillator.
Phi 1 detector filter is made by external components at pin 50. Phi 1 time constant is automatically controlled by
software for broadcasting signals. For video signals (AV and program 99) constant is always fast to prevent top
bending on the screen.
- LBF (pin 34): Line Fly Back input, is obtained by the network R3456/55 (Diagram D) and R3371/T7372.
- Sand Castle (pin 34): Sand Castle output obtained at this pin is used only internally. Levels of sandcastle pulse are
5.3V for burst detection, 3V for line blanking and 2V for frame blanking.
- Horizontal Phi 1 detector (pin 16): The flyback position respect line blanking on TRC cathode is controlled by this
circuit. Phi 1 detector filter is made by C2305 pin 16. Horiz. shift can be adjusted by I2C ( see chapter 8)
- HOUT (pin 33): Horizontal output is an open collector which one drives the horizontal driver stage (T7440 diagram
D).

7.1.7 Vertical synchro and vertical drive

- Vert. sync. separator: It is an internal integrator to separate frame sync. pulses from CVBS.
- Vertical divider system: The divider system uses a counter that delivers the timing for the vertical ramp generator in
the geometry processor. The clock is derived from the horizontal line oscillator. Mode used is automatic 50/60Hz
identification with 50Hz priority.
- Vertical sawtooth generator (pin 25, 26): A reference current of 100mA is realized at pin 25 by means of an internal
reference voltage (3.9V) and resistor R3341. This 100mA reference current is used to derive a
16mA current to charge C2340 (pin 26) during vertical scan. The charge current can be adjusted with the I²C bus
control, (VERT. SHIFT). The external capacitor is discharged during vertical retrace by the vertical divider system.
- Vertical geometry processor: The saw tooth signal that is derived from the sawtooth generator can be controlled by
I²C bus. Control adjustments are: S-CORRECT, VERT.SLOPE, VERT.AMP and VERT.SHIFT (See chapter 8).
- Vert. output stage (pins 21, 22): The vertical geometry processor has a differential current output to drive a DC
coupled frame deflection (7401).
- EHT compensation (pin 36): A voltage inversely proportional of beam current, proceeding of pin 8 of line transformer
(5545 diagram D) is applied to pin 36 to stabilize vertical amplitude from EHT variations.
- Vertical guard input (pin 50): A vertical retrace pulse proceeding from pin 8 of IC7401, is added to cut-off voltage at
pin 50 (this pin has 2 separated functions, cut-off function see chapter 7.1.5). If there is not pulse or its level is not
correct (should be above 3.65V, 0.8msec.), the set goes to standby mode. (See chapter 7.7.1 Protections).

7.1.8 Microcontroller/ Text

Following there is an explanation of the different functions of the microcontroller indicating pins number assigned:
- Tuning (pin 4): The unit has a VST (Voltage Synthesized Tuning) system. This system works by tuning to a station on
the tuner through a linear variation of the tuning voltage (V-VARI) from 0V to 33V applied on pin 2 of the tuner. It is
generated on pin 4 of the µC and converted to an adequate level for the tuner using T7605.
While searching, µC are always reading internally AFC (Automatic Frequency Control) and video identification signals.
When video signal is identified, µC stops searching and do a fine tuning to reach a right AFC value.
- Control key (pin 5): Pin 5 is activated by a DC voltage. When control keys are not activated, a voltage of 3V3 is
produced by R3618. If one control key is activated, this pin is connected to ground directly or by a resistor R3665,
R3667 (Diagram C), decreasing its voltage.
There are 3 voltage levels depending of the key used: 0V for MENU, 1V for P- and 1.9V for P+.
- Mute output (pin 6): This pin is a 3 state output used to control the sound amplifier (see chapter 7.4). States are 0V,
open and Vcc (3.3V).
- INT/EXT input (pin 7): The set can switch to external (AV on the screen) by remote control (selecting program 0) or
by rise edge at pin 8 of euroconnector (see diagram C). The IC switches internally video and audio to external. In both
cases the user can switch to internal changing the channel.
- Band switching (pin 8, 11): There are 2 outputs for band switching pin 11 for VHFI and pin 8 for VHFIII. The µC
controls the channel band in the tuner by a voltage of +5V at the correspondent output. UHF band is controlled by
means of transistor 7601. If the set is in VHF, one of the pins 8 or 11 are high and transistor conducts in such a way
the UHF voltage is 0V. If the set is in UHF, pins 8 and 11 are low, transistor is cut and the set is in UHF.
- LED (pin 10): The LED (D6663 diagram C) lights up with a low current when the television set is ON and with a high
current when the set is on Standby. While the set is receiving a remote control signal, the led is blinking.
- Picture controls (brightness, contrast, colour, sharpness) are processed internally by I2C bus.
- Sound controls (pins 2, 3):
Mono sets: Sound controls are processed internally by I2C bus
Stereo sets: All information necessary to control stereo functions including sound controls, are processed by a
communication I2C bus between the µc and the stereo decoder (IC 7101 pins 4, 5).
- Standby (pins 1, 33): When the set is switched to stand by, line stops (pin 33). In addition to this, pin 1 switch to low
level to make Power Supply in burst mode (see stand by 7.5.3).
- OSD outputs: The RGB and fast blanking signals used for On-Screen Display (OSD) and also for TXT are internally
inserted to RGB outputs (pins 51, 52, 53).
- Oscillator (pins 58, 59): A 12-MHz oscillator is determined by a 12-MHz crystal (1679) between pins 58 and 59.
- P.O.R (pin 60) . : Power on reset (POR) is internal, activated when the set is switched on. If the µC shows abnormal
behaviour it is advisable to reset it switching off/on the set. Reset can be done also by a short circuit between pins 60
and 61.
- RC5 (pin 62): The commands transmitted by the remote control handset are received by infrared receiver (1685) and
passed to the microcontroller for decoding.
- EEPROM (pins 63 and 64): The microcontroller is connected to non-volatile memory IC7685 (EEPROM) via bus I2C.
The following information are stored in the memory:
- Channel data including tuning voltage and band of all the channels.
- Personal preferences (PP), menu mix and child lock on user menu.
- All settings included on Service Menu.

7.1.9 Supplies and decoupings

- Small signal analog supply (pins 14, 39): The same +8V supply coming from line deflection is connected to pins 14
and 39 for small signal processing. A separated supply (C2036) feeds video and sound traps circuit.
If +8V supply is not present at pin 39 or pin 14 during the first 4 seconds after switch ON the TV set, the
microprocessor goes to Standby mode (See chapter 7.7 Protections) .

- Digital supply (pins 54, 15): A +3V3 supply is used for digital circuit of TV processor (pin 54). A decoupling capacitor
for this supply is present at pin 15 (C2301). Pin 54 is used also to supply the µC.
- Bandgap decoupling (pin 19): The bandgap circuit provides a very stable and temperature independent reference
voltage of 4.0 V which one is used specially in the analogue video processor part.
- µC supplies (pins 54, 56, 61): The µC has several +3V3 supplies,
− Pin 54: Analogue supply (Oscillator, ADC).
− Pin 56: Digital supply to µC core.
− Pin 61: Supply to all output ports of theµC.
When the set is in stand by, the µC switch to stand by mode, only 3V3 supplies are present but consumption is
reduced.

7.2 RGB AMPLIFIERS (diagram B)

The RGB signals available at pins 51, 52 and 53 of IC7015 (Diagram A) must be amplified and inverted in order to
reach the level required for driving the tube. The integrated circuit IC7200 (TDA6107) is used for this purpose.
RGB inputs (pins 2, 3, 1): These signals are connected to negative inputs of internal operational amplifiers. There is
and internal reference voltage of 2.5V for the amplifiers. Negative feedback of amplifiers are internal resistors.
RGB outputs (pins 8, 7, 9): These outputs are applied to the RGB cathodes of the tube. Clamping diodes to +200V
(6201, 6216, 6229) and 1K5 series resistors (3203, 3216, 3229) are added for flash-over protection.
- Continuous Cathode Calibration (CCC) (pins 50): This circuit is an auto-tuning loop which stabilizes the black level
(offset) as well as the cathode drive level (gain) of each gun. Pulses in 3 consecutive lines R, G and B (pins 51, 52,
53) at the end of frame blanking are used on alternating fields, one field for black level, following for cathode drive
level.
Cathode currents
- Cathode current feedback (pin 5): Cathode current used in Continuous Cathode Calibration circuit (See 7.1.5)
is obtained at this pin and feedback to pins 50 of IC7015 (Diagram A)
- White adjustment: Gain and cut-off point of RGB amplifiers can be adjusted by I2C in the service menu (See chapter
8)
- Anti-spot circuit: When the set is switched off, the capacitor 2208 keeps charged and a negative voltage is put at
VG1 of the tube.

7.3 DEFLECTION (Diagrams A, D)

7.3.1 Frame deflection (Diagrams A)
Full bridge vertical deflection output performed by the integrated circuit TD8357J (7401).
- Frame supplies (pins 3, 6): There are 2 supply voltages, +12V (pin 3) is the main supply and +45V (pin 6) is used to
supply the output stage during flyback time.
- Vertical inputs (pins 1, 2): (pins 21, 22): The output currents proceeding from pins 21, 22 of IC7015 are converted to
voltages by resistors R3411/12 in such a way that 2 inverted sawtooth are present in the differential inputs of amplifier
(pins 1, 2).
- Vertical outputs (pins 4, 7): Vertical output is DC coupled to deflection coil. That means linearity adjustment is not
necessary. HF loop stability is achieved by a damping resistor R3413.
- Feedback input (pin 9): A voltage proportional to current deflection is present in R3415/16 and a feedback to pin 9.
- Vertical flyback: This signal is internally added to vertical output (pin 7) using supply voltage at pin 6.
- VGUARD circuit (pin 8): This circuit generates a high level during flyback period, and is used to protect the TV set in
case of a vertical failure. (See protections, chapter 7.7)

7.3.2 Line deflection (Diagram D)

The final line transistor is driven by the transformer 5441, whose primary winding is driven by the transistor T7440
connected to the line drive output of IC7015 (pin 33).
The horizontal deflection stage is carried out in a conventional way, with the deflection transistor (T7445) and line
transformer (5445).
Beam current info (BCI) is present at C2460.
There are the following supply voltages obtained from line transformer (5545):
- Frame supply (+12B):Main frame supply present at capacitor C2455.
- Flyback frame supply (+45 ): Flyback frame supply present at capacitor C2455.
- +8V stabilizer: +8V for small signal is made from +12V (C2454) by D6474 and T7478
- +5V stabilizer: And additional voltage of +5V for small signal is made also from +12V (C2454) by D6479 and
T7479.
- Stereo supply (only stereo models): +12V from C2454 is drived to 7702 (Diagram E) to stabilize +5V for stereo
decoder (7101.
- FF : The heather voltage is reduced by R3235/38 and 5235 (Diagram B) to obtain 6.3Veff at the CRT .

7.4 SOUND AMPLIFIER (Diagram C)

Sound amplifier is a Bridge Tied Load (BTL) amplifier including short circuit protection, mute and stand by mode.
IC used can be TDA8941P for 14" and 17" models, TDA8943SF for 20" and 21" models or TDA8944J for stereo
models. Behaviour is the same for 3 models. TDA8944J is a double amplifier, that means 2 supplies, 2 inputs and 2
outputs.
- Supply (Vcc, SVR): Main supply (Vcc) is taken from +11V of Power Supply (C2540 diagram D). The IC creates
internally a half supply, present in SVR pin and decoupled by 10uF capacitor (C2182).
- Sound input (IN+): Amplifiers have differential inputs (IN+,IN-). Audio input is connected to IN+ decoupled by 220nF
capacitor (C2181/84) and IN- is decoupled to ground by other 220nF capacitor (C2179/93). To avoid oscillations there
is a 1n5 (C2183/95) capacitor connected between both inputs.
- Mode input (MODE): This input is commanded by mute signal proceeding from the µC (pin 6 of 7015 diagram A)
and has three modes depending of the voltage level:
- Standby mode (Vmode = Vcc): Consumption is very low (used during stand by).
In this case Vmute=0V, T7657 and T7659 are cut, MODE signal is high
- Mute mode (2.5V<Vmode<Vcc): No sound output (used when the set is switched on/off, there is no signal,
channel search, change of program, etc.)
In this case pin 6 of 7015 is open T7659 conducts (by resistor divider), T7657 are cut, MODE voltage is
5,5V.
 - Operating mode: (Vmode<0.5V): Sound output present (normal operation).
In this case Vmute=3V3 both transistors conduct, mute signal is low.
- Sound output (OUT+/OUT-): Amplified sound is drived to the loudspeakers.

Mono sets:
Headphones output has been connected in such a way that when headphones are connected, loudspeakers are
switched off.
Stereo sets:
Headphones output are coming directly from pins 57 and 58 of stereo decoder IC7101 (see chapter 7.6 and
diagram E).

7.5 POWER SUPPLY (Diagram D)

Mains isolated switched mode power supply (SMPS). controlled in variable frequency mode.
IC7514 (KA5Q075RT) includes control circuit and output MOSFET. Output feedback is done by means of an
optocoupler (7515).
- Switching behaviour: The switching period is divided in on-time, when energy is extracted from the mains into the
primary winding (8-12 of 5525), off-time, when energy in the transformer is supplied to the loads via secondary
windings of 5525 and dead-time when no energy is extracted or supplied.
- Standby mode: Output voltages are present when the set is in stand by. Standby is done cutting line deflection and
making the supply in burst mode in such a way that power consumption is very low.

7.5.1 Degaussing and Rectifier

- Degaussing: R3501 is a dual PTC (2 PTC's in one housing). After switch on set, PTC is cold so low-ohmic and so
degaussing current is very high. After degaussing, PTC is heated so high-ohmic, so in normal
operation degaussing current is very low.
- Rectifier: Mains voltage is filtered by L5500, full wave rectified by diodes D6502-D6505 and smoothed by C2505
(300V DC for 220V AC mains).

7.5.2 Regulation
- Power MOSFET (pin 1): Power stage is done by an internal MOSFET between pin1 and ground. Current is sensed
by an internal resistor and limited to 5A peak. (See chapter 7.7.2 Protections)
- Start up and supply (pin 3): When the set is switched on, a current via R3527 and R3528 is applied to pin 3. When
C2514 is charged to 15V, the power supply starts and the internal MOSFET conducts. A voltage across transformer
windings is built up. The voltage across winding 4-2 is rectified by diodes D6523/25 and used to supply the IC on pin
3.
Voltage of pin3 depends on the output voltage and is about 28V. If Vpin3 is lower than 9V supply stops and if it is
higher than 32V, output voltage is limited. (See chapter 7.7.2 Protections)
- Sync (pin 5): A pulse voltage proceeding from winding 4-2 is applied to this pin. A delay is added by means of C2524,
R3522 and R3526 to synchronize starts conduction of MOSFET at minimum Vds voltage.
- Secondary feedback (pin 4): Line supply feedback is obtained at pin 4 by divider R3531/34/19, the differential
amplifier (IC7533) and the optocoupler (IC7515). Voltage at this pin is about 1.1V
- Output regulation: IC7514 stabilizes output voltage by controlling T-on and so the frequency and the duty cycle.
Output control is done by the following way:
If line output is higher, current input of the differential amplifier (IC7533) is higher (amplifier has a reference
voltage of 2.5V).
Current in IC7533 and also in the optocoupler (IC7515) is higher.
Voltage in pin 4 is lower, T-on is internally reduced and output is reduced.
Output voltage of supply can be adjusted by R3518.

7.5.4 Secondary side

- Line supply: Line supply present at capacitor C2530 should be adjusted to the correct value (depending on the
TRC) by means of P3534.
- Sound supply (+11V): This supply is used for sound output amplifier and to feed 3V3 stabilizer.
- µC supply (+3V3): +5V3 is regulated by T7575, D6570 and T7571.

7.5.3 Stand by:

When the set is put in standby, line driver (pin33 of IC7015, diagram A) stops and deflection supply is not loaded. Only
a reduced load to supply the µC (+3V3) is necessary.
To reduce more the power consumption, during standby T7572 is cut by STBY signal (pin1 of IC7015, diagram A),
then current in IC7533 is increased by means of D6531 and output voltages are reduced.
As a consequence of this, the supply switch to burst mode operation. During working time C2514 is charged till 12V,
then supply stops and C2514 is discharged till 11V.
7.6 STEREO DECODER

The CTU Stereo chassis is based in the TDA9875A chip. This is a single-chip Digital TV Sound Processor for analog
and digital multichannel sound systems in TV sets.

In the stereo chassis the sound part in the IC7015 (TDA9350) is disabled. All sound signal, analog and digital is
processed in IC7101 (TDA9875A).

The TDA9875A decodes NICAM signals (B/G and I standard) and two-carrier FM modulation A2 signals (B/G
standard).

- Control bus (pins 4, 5): Stereo is fully controlled for the µC of IC7015 (Diagram A) via I2C-bus. Status information
present in internal registers of IC7101 is read by µC to determine whether any action is required. Control is exercised
by the µC also, writing in other internal registers of IC7101. This control includes volume, balance, bass, treble,
pseudo stereo, spatial, and Automatic Volume Level (AVL).
- Oscillator (pins 18, 19): The circuitry of the crystal oscillator is fully integrated, only a external 24.576 MHz crystal is
needed.

- SIF input (pin 12): SIF signal is filtered from video signal coming from pin 38 of IC7015 (Diagram A) by a passband
5.5MHz to 6.5Mhz filter (C2740/41/42 and L5741).
- AGC, ADC: SIF is passed through an AGC circuit and then digitized by an 8-bit ADC operating at 24.576 MHz. The gain of
the AGC amplifier is controlled from the ADC output. Then signal is separated in 2 ways, one for FM and other for NICAM.
- FM demodulation: FM signal is fed via a band-limiting filter to a demodulator. If signal is stereo A2, decoder recovers the
left and right signal channels from the demodulated sound carriers. A stereo identification signal is sent to the µC.
- NICAM demodulation : NICAM signal is transmitted in a DQPSK code at a bit rate of 728 kbit/s. NICAM demodulator
performs DQPSK demodulation and feeds the resulting bitstream and clock signal onto the NICAM decoder. A timing loop
controls the frequency of the crystal oscillator to lock the sampling rate to NICAM decoder: The device performs all
decoding functions in accordance with the “EBU NICAM 728 specification”.
- Audio processing: After demodulation, digital signal is selected (FM, A2 or NICAM) and processed according µC control.
Following functions are provided: Forced mono, stereo, channel swap, channel 1, channel 2, spatial effects, Automatic
Volume Level (AVL), volume, balance, bass and treble.

- DACs (pins 54, 55): Then signals are transformed to analog by DACs and sent to the outputs. Post filter capacitors for
DACs are at pins 54 and 55.

- Sound outputs (pins 60, 61): After a volume control (by I2C), sound outputs (MAIN R and MAIN L) are drived to the
inputs IN+ (pins 12 and 6) of the final sound amplifier IC7187C (Diagram C).
- Headphone outputs (pins 57, 58): Headphone outputs are drived by followed emitters 7780 and 7781 to the
headphones. These outputs are independent of loudspeakers outputs and controls are separated.
- External audio out (pins 47, 48): Signal at these pins are drived directly to the euroconnector sound outputs (see
Diagram C).
- External audio in (pins 33. 34): External audio (R and L) proceeding of pins 6 and 2 of euroconnector (Diagram C) is
applied pins 33 and 34 of IC7101 and digitalized by an ACD circuit. Selection between internal or external is done from
the µC (IC7015) by I2C bus (see INT/EXT, chapter 7.6).
- External audio out (pins 47, 48): Signal at these pins are drived directly to the euroconnector sound outputs (see
Diagram C).

- +5V stabilizer: +5V supply for stereo processor is obtained from +12V (C2454 diagram D) by D6702 and 7478. This
voltage comes to supply voltages of IC1701 (pins 59, 15, 64)
- Digital supplies (pins 15, 64): +5V supplies at pins 15 and 64 are used for digital circuits of stereo processor.
Power ON reset (pin 16): When the set starts, C 2754 is slow charged by an internal 50K resistor to +5V. When digital
supplies are present and oscillator is working, reset is done if pin 16 is low (Vpin16<1.5 V).
- Analog supply voltage (pin 53, 59): There is a +5V supply for analog outputs (DACs and operational
amplifiers) at pin 59. A 50% reference voltage (2.5V) for these circuits is present at pin 53.
- ADC supply voltage (pins 38, 39, 40, 46) : A 3.3V supply voltage is obtained internally and decoupled on pin 38 by
C2758. Positive and negative reference voltage for ADC is present at pins 39 and 40. A 50% reference voltage (1.65V)
for ADC is present at pin 46.
- Front-end supply (pins 7, 8, 11) : A separated 3.3V supply voltage (decoupled on pin 7 by C2750) is necessary for SIF
demodulator. By means of a 200mA current generator at pin 8, a 2V reference voltage is produced at pin 7.
7.7 PROTECTIONS

If TV does not start or it switches to stand by, try to start again in a few minutes and if problem remains check
protection pins explained following.

7.7.1 Protections in IC7015 (Diagram A)

- Pins 14, 39:

If +8V supply is lower than 6V (pin 39 or pin 14) during the first 4 seconds after switch ON the TV set, the
microprocessor goes to Standby mode (See also chapter 7.1.9).

- Pin 50:
If the vertical retrace pulse at this pin is not correct (should be above 3.65V, 0.8msec) during the first 4 seconds after
switch ON the TV set, the vertical guard blanks the RGB outputs and the TV switch to Standby (See also chapter
7.1.7).
This protection operates in the following situations:
- When the vertical deflection fails and there is no pulse.
- When the vertical retrace pulse is higher than 0.9msec. (for example vertical amplitude is too high)
- An extra protection is obtained when there is too much current in the CRT (for example +200V supply is
missing), because in this case, DC level of pulse is lower by means of cut-off signal. (See fig. 7.7.1)

6v

3.65v 3.65v
2,8v
Correct
Vertical 3,2v Failure
Deflection 0.8v

0 mS 20 mS 0 mS 20 mS

Fig 7.7.1 Vertical guard protection

To repair the set more easily, Vguard protection can be disabled, in this case the vertical guard blanks the RGB
outputs, but TV does not enter in Standby mode. To disable Vguard, item 8 of Service menu MANUAL C-O should be
01 (See chapter 8.1).
Due to a change in MANUAL C-O is difficult to do if the set switch to Standby, Vguard can be disabled also connecting
a diode (1N4148) in series with a 2K2 resistor between pins 10 and 7 of IC7015 (Anode at pin 10). Be careful to
disconnect this network after the set is repaired.

7.7.2 Protections in IC7514 (Diagram D)

- Pin 1:
Primary current is sensed by an internal resistor for the IC. If this current is increased to 5A peak, supply works in a
intermittent way (ON and OFF). That can be provoked for a short circuit on secondary outputs.

- Pin 3:
If Vpin3 is lower than 9V the under voltage protection stops the supply.
If Vpin3 is higher than 32V over voltage protection limits output voltage.
8.- ELECTRICAL ADJUSTMENTS
8.1 Service mode
The signal processor IC7015 is fully controlled by I2C, so that the most of adjustments of the set can be made by
service menu.

- Enter in Service mode:

- Select program 75 and press at the same time OSD key (+) on RC and MENU key on local key board during 4
seconds.
Service mode is indicated by a S symbol on the down left corner of the screen.
Note : Controls (volume, contrast, brightness and saturation) will be pre-adjusted to the mid position.
- Display Service Menu : When the set is in service mode it is possible to display Service Menu by OSD key (+) on RC.
Using P+, P- keys of remote control the different items can be displayed (see table 8.1):

ITEM Value ITEM Value

Nº Description Hexa Nº Description Hexa
1 ADJUST VG2 PRG 13 R GAIN 20H
2 CATH.DRIVE 0CH 14 G GAIN 20H
3 TXT V-SHIFT 02H 15 B GAIN 20H
4 TXT H-SHIFT 02H 16 S-CORRECT 20H
5 V-GUARD DISA PRG 17 VERT.SLOPE 20H
6 AGC START 25H 18 HOR.SHIFT 20H
7 RESERVED 19 VERT.AMP 20H
8 MANUAL C-O 01H 20 VERT.SHIFT 20H
9 R CUT-OFF 20H 21 SYS OPTIONS 00H
10 G CUT-OFF 20H 22 MENU OPTIONS 00H
11 BRIGHTNESS PP 23 READ STATUS PRG
12 CONTRAST PP 24 RESERVED 00H

Table 8.1. Service menu. Settings are hexadecimal values

- Pre setting values: When E2PROM is replaced, pre-setting values indicated on table 8.1 are stored by the µC. (see
8.7 E2PROM).
- Adjust by Service Mode: When a item is selected, using V+, V- keys of remote control it can be adjusted. Items 2, 5,
23 and 24 have fixed values = pre setting values, rest of items see 8.2 to 8.6.

- Remove service menu: There are 2 ways to remove service menu

- Saving the new settings: Using OSD (+), MENU or INSTALL keys on RC.
- Keeping the old settings: Switching the TV to stand by. Service mode continues active.

- Remove Service Mode: Switching off the TV

8.2 Power supply and focusing:

- Power supply voltage:
- Adjust brightness and contrast controls at minimum.
- Connect a DC voltmeter across C2530 (Diagram D).
- Adjust R3534 for a required voltage depending on the model and the TRC used ( see table 11, page 23).
- Focusing:
- Adjust with the potentiometer placed on the line output transformer.
8.3 AGC Adjustment
- Connect a pattern generator to the aerial input with RF signal amplitude = 1mV.
- Adjust the value of AGC start (item 6 of Service menu) so that voltage at pin 1 of the Tuner (1001) is 3.7V.

8.4 White D
8.4.1 Manual cut-off:

Item 8 of adjusting values should be 00 (see table 8.1), that means set is in automatic cut-off. However it is possible
that RGB do not start (black picture), due to grid 2 is not adjusted. In this case we recommend to change to Manual
cut-off ( Item 8 = 01), pre-adjust grid 2 to have a good picture and change to automatic cut-off ( Item 8 = 0) before
continue adjusting (see warm-up detection circuit in 7.1.5)

8.4.2 Grid 2:
- Connect a white pattern generator.
- Adjust contrast at 00 and brightness at 36. (00 and 24 in the service menu because hexadecimal values are used
- Put parameter 1 of the service menu ADJUST VG2 = 1. An arrow will be displayed on the left upper corner.
- Adjust VG2 potentiometer ( in line transformer ) till the arrow will be transformed to a square.
- In a few seconds, arrow will be disappear and ADJUST VG2 parameter will be come back to 00.

8.4.3 White checking:

- Connect pattern generator containing grey scale

- Adjust the set to normal operation and reduce the saturation control to minimum.
- Allow the set to warm up about 10 minutes and check visually if the grey scale has correct colour.
- If not, enter to Service menu and adjust G and B gain (items 14 and 15) until a desired grey is obtained. In the
case that adjusting is difficult, start again with the setting values of table 8.1 (items 9, 10, 13, 14, 15).

8.6 Geometry

- Connect a circle pattern generator with the controls at nominal conditions and enter to service menu.

Adjust to have picture centred in vertical position by service menu item 16.

- Horizontal shift:
Adjust to have picture centred in horizontal position by service menu item 18.

- Vertical amplitude:
Adjust picture height to cover the screen by service menu item 19.

Adjustments only if necessary:

- TXT Shift:
Vertical and horizontal shift of OSD or TXT can be adjusted by items 3 and 4 of service menu.

- Vertical slope:
When item 17 is selected, only upper part of the screen can be seen. Vertical slope is adjusted when centre line
of the pattern is just visible.

- Vertical S correction:
S correction can be adjusted by item 20 of service menu.
8.7 Options:
The type of chassis is defined by items 21 and 22 of service menu. The following alternatives are available:

SYSTEM OPTIONS (Item 21) VALUE MENU OPTIONS (Item 22) VALUE
PAL B / G 00 16 Languages menu 00
PAL - I 01 English bars menu 01
Global menu (without languages ). 03

Important note: All the chassis have identification sheet when the chassis type is indicated:
"Cod. service: SXXMXX", where SXX means the option of system and MXX means the option of menu

Example: S01M00 means system = 01 (Pal I) and menu = 00 (13 Languages menu)

When the chassis or the EEPROM (IC7685) have to be replaced, be careful to keep the same type of chassis, setting
correctly the chassis options.

8.8 Error messages

The microcomputer also detects errors in circuits connected to the I2C (Inter IC) bus. These error messages are
communicated via OSD (On Screen Display) :

Error message Error description Component

F2 Eprom communication error IC7685
F3 µC internal error (RA M) IC7015 (µC)
F4 Internal bus communication IC7015
F5 SDA2/ SCL2 bus wrong communication IC7101 (stereo)
No sound menu SDA2/ SCL2 bus no communication IC7101 (stereo)
F6 Eprom data error IC7685
F7 Not allowed options * Item 21,22 service
menu.
F8 Vertical guard pin 50, IC7015

* If SYS OPTIONS or MENU OPTIONS are not possible in this chassis, the µC change to allowed options and first
time TV set is switch on F7 message is displayed. Options should be checked ( see 8.7)
9. Safety instructions, maintenance instructions,
warning and notes

Safety Instructions for Repairs Warnings

1. Safety regulations require that during a repair:
1.In order to prevent damage to IC's and transistors any flash-over of
- The set should be connected to the mains via an isolating
the EHT should be avoided. To prevent damage to the picture tube
transformer.
the method, indicated in Fig. 9, has to be applied to discharge
- Safety components, indicated by the symbol ! should be
the picture tube.
replaced by components identical to the original ones
Make use of an EHT probe and a universal meter is 0V (after approx
- When replacing the CRT, safety goggles must be worn.
30s).

2. ESD.
2. Safety regulations require also that after a repair: All IC's and many other semi-conductors are sensitive to electrostatic
- The set should be returned in its original condition. discharges (ESD). Careless handing during repair can reduce life
- Τhe cabinet should be checked for defects to avoid touching, by drastically. When repairing, make sure that you are connected with
the customer, of inner parts. the same potential as the mass of the set via wrist wrap with
- The insulation of the mains lead should be checked for external resistance. Keep components and tools on the same potential.
damage.
- The mains lead strain relief should be checked onits function 3. Proceed with care when testing the EHT section and the picture
- The cableform and EHT cable are routed correctly and fixed with tube.
the mounted cable clamps in order to avoid touching of the CRT,
hot components or heat sinks 4. Never replace any modules or any other parts while the set is
- The electrical resistance between mains plug and the secondary switched on.
side is checked. This check can be done as follows:
• Unplug the mains cord and connect a wire tween the two pins 5. Use plastic instead of metal alignment tools. This will prevent any
of the mains plug. short circuits and the danger of a circuit becoming unstable.
• Switch on the TV with the main switch.
• Measure the resistance value between the pins of the mains 6. Upon a repair of a transistor or an IC assembly (e.g. a transistor or
plug and the metal shielding of the tuner or the aerial IC with heatsink and spring) remounting should be carried out in
connection on the set. The reading should be between 4.5 M the following order:
and 12 M. 1. Mount transistor or IC on heatsink with spring.
• Switch off the TV and remove the wire between the two pins of 2. Resolder the joints.
the mains plug.
• Thermally loaded solder joints should be oldered. Notes
-This includes components like LOT, the line utput transistor, fly-
back capacitor. 1. After replacing the microcomputer first solder the shielding before
testing the set. This is needed as the shielding is used for earth
Maintenance Instructions connection. If this is not done the set can switch into protection
mode (see description of the SMPS).
It is recommended to have a maintenance inspection carried out
periodically by a qualified service employee. 2. Do not use heatsink as earth reference.
The interval depends on the usage conditions.
- When the set is used in a living room the recommended interval 3. The direct voltages and waveforms should be measured relative to
is 3 to 5 years. When the set is used in the kitchen or garage this the nearest earthing point on the printed circuit board.
interval is 1 year.
- During the maintenance inspection the above mentioned "safety 4. Voltages and oscillograms in the power supply section have been
instructions for repair" should be caried out. The power supply measured for both normal operation ( ) and in the stand-by
and deflection circuitry on the chassis, the CRT panel and the mode ( ). As an input signal a colour bar pattern has been used.
neck of the CRT should be cleaned.
5. The picTure tube PWB has printed spark gaps. Each spark gap is
connected between and electrode of the picture tube and the
Aguadog coating.

FIG. 9

21