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Tatung Vibrant VM77S, Service Manual

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Tatung Vibrant VM77S Service Manual Download Page 24

Page 23

Troubleshooting

 VM77S

5-7 R.G.B. Video Amplifier Abnormal

Check or replace the

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 present  at the

pin of the CRT R.G.B.

Cathode

Defective cut-off circuit

(DC restore) I504

Summary of Contents for Vibrant VM77S

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

Page 2: ...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 Diagrams Inserted 11 Schematic Diagrams Inserted ...

Page 3: ...r 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 not lodged between the chassis and other metal parts in the monitor 2 Inspect all protective devices such as nonmetallic control knobs insulating materials cabinet backs adjustment and compartment covers or sh...

Page 4: ...stalling 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 wires around the component before soldering 4 When replacing a high wattage resistor 0 5W metal oxide film resistor in the circuit board keep the resistor about 1 cm 1 2 inch away from the circuit board 5 Keep ...

Page 5: ... 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 all connections are well contacted c Turn on monitor power and tester power d Press Test button e If green light shows up means test OK If red light shows up means test fails f If the Tester has a digital disp...

Page 6: ...nization 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 rated voltage 100VAC to 240VAC Misconvergence Center Area 0 3 mm Corner Area 0 4mm User Controls Power On Off Contrast Brightness Horizontal Size Horizontal Position Vertical Size Vertical Position Pincushion Trapez...

Page 7: ... 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 Blue video 11 Ground 4 Ground 12 SDA 5 NC 13 H Sync 6 Red ground 14 V Sync VCL 7 Green ground 15 SCL 8 Blue ground ...

Page 8: ...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 Active us 25 42 20 32 17 778 16 162 14 22 13 11 852 10 836 F F P us 0 636 0 51 1 556 0 323 0 569 0 203 0 444 0 508 V freq Hz 59 95 75 85 75 85 75 03 60 85 Sync Polarity O Period ms 16 68 13 33 11 764 13 333 11 76 13 3...

Page 9: ...ble 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 the keyboard or mouse is activated The recovery time from Active OFF state back to ON state is around 10 seconds For power consumption 75W Max 230V AC preset size and maximum light output condition ...

Page 10: ...ull 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 RAM and stack area 32k bytes of OTP ROM 13 channel 8 bit PWM D A converter 2 channel A D converters for key detection saving I O pins internal H sync and V sync signals processor providing mode detection and an ...

Page 11: ...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 width corner and trapezoid correction are also accomplished by thispin 11 The DC levelcontrols H size The AClevelis combined with side pin and trapezoid corners functions 3 3 5 X Ray Protection 1 To avoid X ray h...

Page 12: ...on 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 It consists of C803 T801 C804 C805 C808 C819 C807 C817 and meets EMI regulation 3 4 3 Power LED Status 1 The LED has 3 leads with common cathode to emit green and amber color light for different power saving stat...

Page 13: ...er 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 via L811 D813 C824 and the gate control of Q451 comes from I401 pin 6 via Q450 Q434 D435 and R4E5 The duty cycle is controlled by I701 pin 33 PWM pin Adj via R719 C741 R4F6 R4F5 R4F1 2 The regulation and boost up...

Page 14: ...701 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 7 8 2 The OSD R G B signals and blanking signal are terminated at I502 pin 15 14 13 and 12 to I501 pin 1 2 3 and 4 then the OSD picture appears ...

Page 15: ...C 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 6 Screwdriver 4 1 3 Switching Power Supply and Regulator Adjustment a The regulated B control has been preset in the factory and needs no adjustment However if any repair is made on the power supply section the follo...

Page 16: ...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 raster0 01 0 02 FL CONDITION Display image 50 mm x 50 mm white block pattern PROCEDURE 2 65000 Kcolortemperature setting 2 a SetBrightness to cutoffand Contrastto maximum 2 b Move cursoron OSD to choose color temperature ...

Page 17: ...02 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 and green lines in the center area of the display Note The monitor requires 30 minutes of warm up time for convergence adjustment CONDITION Display image Crosshatch pattern Warm up Time 30 minutes PROCEDURE 1 Set Bri...

Page 18: ...ually 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 instead of canceling the effect of the stray fields 3 Rotate the individual rings of 4 pole convergence magnets by changing the spacing between the 2 tabs to converge the vertical red and blue lines at the center of t...

Page 19: ...703 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 T402 pin 2 on PWB MAIN No Raster 0 V High 75 V or more Check DC B line Q451 Q402 T402 Yes Check voltage of C808 No ...

Page 20: ...M77S 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 Replace I502 ...

Page 21: ...03 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 ...

Page 22: ...eck 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 I301 waveform Still no vertical scan Check or replace CRT Replace I401 No ...

Page 23: ...izontal 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 sync pin 42 of I701 Check or replace C303 I401 Yes Verizontal sync present at pin 14 of I401 Check I401 pin 24 waveform Out of Verizontal Synchronization No Yes No Check I401 pin 13 pin 14 ...

Page 24: ...able 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 present at the pin of the CRT R G B Cathode Defective cut off circuit DC restore I504 ...

Page 25: ...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 IC LM2479 8P NS 14 I701 6448014500 IC MTV212 M A S32 40P PDIP MYSON 15 I703 6448015720 IC MTV24C08 MYSON 16 I705 6442000875 IC KIA78L05 SAMSUNG 17 I801 6442031600 IC 5S 0765C 5P FAIRCH 18 L404 6111274130 COIL CHOKE 2 7...

Page 26: ...1127852 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 FBT TFB 7020 CF1837 LIEN CHANG S1 33 T403 6136001300 6136001301 XFRMER DYNAMIC TDF 1012 EI19LSE S0 XFRMER DYNAMIC TDF 1013 EI19HJC S1 34 T801 6138001603 LINE FILTER TLF 1016C 16mH LSE 35 T802 6131042221 6131042231 XFRME...

Page 27: ...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 GND O R 5V 11 7V Q811 TDA4863J 5V H V SG SDA SCL O R SDA 1 V H Q813 dynamic foucus 650V G1 ABL CLBL HFLB SDA1 SCL1 SW5 V OSD MTV021 5V OSD BLK R G B R G B HFLB ABL R G B R432 12V Vertical Focus 6 3V 12V I705 78L05 Q701 Q70...

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