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Vibrant VM77S, Service Manual

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Page 20

Troubleshooting

 VM77S

5-3

Function Key Abnormal

Put on

I701, I703

Replace X701

No

Check I701 and

I703 missing?

Power

 ON/OFF again and

check X701, oscillator

OK?

Function Key Abnormal

Yes

No

No

Replace I703 or do

ATE again

Yes

Replace I701 and check

uP OK?

Yes

Check

I703 EEPROM content

OK?

No

Replace I705, Q701,

Q702, R728

Check

pin 8 of I701

is 5V?

Replace I701

Yes

Check

ZD709, R735

Yes

No

Summary of Contents for VM77S

Page 1: ...17 inch Color Monitor VM77S Service Manual...

Page 2: ...This manual may not in whole or in part be copied photo copied reproduced translated or converted to any elec tronic or machine readable form without prior written per mission of Tatung UK Ltd VM77S...

Page 3: ...ns 2 2 Product Specifications 5 3 Operation Theory 9 4 Alignments and Adjustments 14 5 Troubleshooting 18 6 Recommended Spare Parts List 24 7 Block Diagram 26 8 Exploded Diagrams Inserted 9 PCB Diagra...

Page 4: ...ting never to exceed 1 1 2 Safety Checks Before returning the monitor to the user perform the following safety checks 1 Inspect to make certain that each lead dress is not pinched or that hardware is...

Page 5: ...ng or installing any component or assembly disconnecting PCB plugs or connectors and connecting a test component in parallel with a capacitor 3 When replacing parts or circuit boards clamp the lead wi...

Page 6: ...st Setup a Test duration 3 seconds b Set current limit at 25 A c The grounding resistance must be less than 0 1 ohm 3 Test Procedure a Plug the monitor power cord to the tester terminals b Make sure a...

Page 7: ...gative Synchronization Frequencies Horizontal 30 to 70 kHz Vertical 50 to 160 Hz Signal Connectors 15 pin D shell connector Video Signals Analog 0 7 Vp p RGB positive Power Input 75 Watts maximum AC r...

Page 8: ...is pin is used for selftest detection Connect this pin to ground at the PC end For PC 99 This pin will provide 5V from PC side Pin Signal Pin Signal 1 Red video 9 5V 2 Green video 10 Digital Ground 3...

Page 9: ...8 63 16 66 15 63 14 56 B Blanking us 6 356 6 35 5 33 5 172 4 409 3 657 3 778 3 725 C Sync us 3 81 2 03 1 556 1 616 1 138 1 219 1 037 1 016 D B P us 1 907 3 81 2 222 3 232 2 702 2 235 2 296 2 201 E Act...

Page 10: ...r power LED Table 2 3 Power Saving Function State Power Consumption LED Light ON Normal Green Active OFF 5 watts Amber The power saving states will be kept until a control signal has been detected or...

Page 11: ...70 kHz 6 Full range AC input and simplified line filter design 3 2 Microcontrol Section 1 This monitor uses MYSON MTV212 M A 32 CPU It contains a 8051 8 bit CPU core 256 bytes of RAM used as working...

Page 12: ...an current is determined by B minusVm the voltage ofC418 valuesand the pincushion control isaccomplished by Darlington pair Q418 and Q419 by coupling a parabola waveform from pin 11 of TDA4841 The H w...

Page 13: ...upply Section 3 4 1 AC Rectifier The circuit can accept 90 V to 264 V AC input through D801 D803 bridge diodes and C808 filtering to get DC 126 V 364 V for power conversion in T802 3 4 2 Line Filter I...

Page 14: ...ite the power 3 4 9 Step Up Power Supply For FBT 1 The B of FBT is proportional to horizontal frequency that is the higher frequency the higher voltage The basic voltage is 58 volts from T802 pin 10 v...

Page 15: ...pulse from I701 pin 34 that goes through R720 to I502 pin 10 and positive horizontal pulse from T402 pin 5 goes through R496 to I502 pin 5 CPU I701 pin 13 12 I2 C bus transfers information to I502 pin...

Page 16: ...ter Sanwa FD 750C or equivalent 2 30 kV high voltage probe HP34111A 3 Oscilloscope TEK2235 or equivalent 4 Minolta Color Analyzer II 5 Signal generator IBM PC with proper display cards or Chroma 2000...

Page 17: ...D cursor and 563 5 atG2 1 b Adjust Rand Bcutoff to min 1 c Adjust Gcutoff toabout 0 45FL 1 d Adjust Bcutoff to get y 280 5 Rcutoff to get x 280 5 and Y 0 65 0 05 FL 1 e Adjust Brightnesscutoff to rast...

Page 18: ...st focus 2 at T402 static focus VR to make horizontal line clear 4 Repeat above procedures to get best focus 4 2 4 Static Convergence Adjustments Static convergence involves alignment of the red blue...

Page 19: ...the field be gradually reduced by moving the coil slowly away from the monitor The degaussing coil must never be shut off or disconnected while near the monitor as this would introduce a strong field...

Page 20: ...heck I401 I703 R719 C741 R4F6 R4F5 R4C4 Check I801 R807 R808 Q801 Q802 ZD802 VR801 Check D801 D802 D803 D804 T801 R804 F801 Yes No Normal 68 V 31 5 kHz Short Circuit at load Measure voltage of B at T4...

Page 21: ...eshooting VM77S 5 2 OSD Abnormal Put on I502 Replace them No Check I502 pin 9 4 is 5V and pin 5 10 7 8 missing Check R517 L514 R527 R523 R524 OK OSD Abnormal Yes No No Replace it Yes Yes Check P502 OK...

Page 22: ...I701 and I703 missing Power ON OFF again and check X701 oscillator OK Function Key Abnormal Yes No No Replace I703 or do ATE again Yes Replace I701 and check uP OK Yes Check I703 EEPROM content OK No...

Page 23: ...tal line Ckeck or replace I301 Check R312 R307 R306 R313 Yes Check I301 voltage of pin 1 is 12V pin 4 is 12V pin 2 is 35V Check pin 5 O P waveform at I301 No Vertical Scan No Yes No Check pin 6 7 of I...

Page 24: ...406 Yes Horizontal sync present at pin 15 of I401 Check I401 pin 8 H output frequency pin 29 waveform Out of Horizontal Synchronization No Yes No Check Q401 T401 Q402 R424 D401 Check signal cable V sy...

Page 25: ...he signal cable or I501 Yes Check waveform at I501 pin 5 6 and 7 Check I502 pin 1 2 and 3 collector voltage normally about 70V waveform RGB Video AMP Abnormal Yes No Yes No Check I901 Video signal pre...

Page 26: ...H BRK 4A 250V 9 I301 6442026400 IC TDA4863J 7P PHILIPS 10 I401 6442030000 IC TDA4841 32P SDIP PHILIPS 11 I501 6442031500 IC LM 1267 24P SDIP NS 12 I502 6442029700 IC LM2469 9P NS 13 I503 6442029900 I...

Page 27: ...5 UEI 29 R802 6221127852 MOF OHM 0 27 1W J HOR 30 R4E3 6221227852 MOF OHM 0 27 2W J HOR 31 T401 6135000801 XFRMER HOR DRIVE THD 1008A EI19 32 T402 6133070190 6133070200 FBT TFB 7019 FEA953 SAMPO S0 F...

Page 28: ...02 VERTICAL O P I301 BLANKING CKT BRIGHTNESS CONTROL SPOT KILLER H DRIVER BRIGHTNESS H OUT DIODE MODULATE FBT STEP UP CKT D Y XRP 80V 150V 650V 6 6KV 115V V V H H P502 P501 25 6KV VTTL GND VIDEO 5 V G...

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Page 34: ...Printed in Taiwan...

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