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Tatung Vibrant VM77S Service Manual

17-inch color monitor
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Service Manual
17-inch Color Monitor
VM77S

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Summary of Contents for Tatung Vibrant VM77S

  • Page 1 Service Manual 17-inch Color Monitor VM77S...

  • Page 2: Table Of Contents

    VM77S Table of Contents 1. Precautions ......................... 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...

  • Page 3: Precautions

    VM77S 1 Precautions Follow these safety and servicing precautions to prevent damage and to protect against potential hazards such as electrical shock and X-rays. nonmetallic control knobs, insulating materials, 1-1 Safety Precautions cabinet backs, adjustment and compartment covers or shields, isolation resistor-capacitor networks, mechanical insulators, etc.

  • Page 4: Servicing Precautions

    VM77S 1-1-3 Product Safety Notices Many electrical and mechanical parts in this chassis have special safety-related characteristics which are often not evident from visual inspection, the protection afforded by them may not be obtained by replacing them with components rated for higher voltage, wattage, etc. Before replacing any of these components, consult the Recommended Spare Parts List given at the end of this manual.
  • Page 5 VM77S Plug monitor power cord to the Hi Pot tester terminals. Turn on tester and watch the indicator or beeper. If the indicator lamp lights, or beeper beeps, the test fails. 1-4 Ground Continuity Test 1. Test Equipment AC low ohm tester TOS-6100 or equivalent approved equipment.

  • Page 6: Product Specifications

    VM77S 2 Product Specifications 2-1 Specifications 17-inch (16-inch Visual image area), sloted mask, 90 degrees Picture Tube deflection, dot type black matrix, medium short persistence phosphor, dark tint, non-glare/ anti-static screen, 0.28 mm dot pitch VGA, Super VGA, 1024x768@60/70/75/85 Hz...
  • Page 7 VM77S 2-2 Signal Cable Pin Connections Table 2-1. Signal Cable Pin Assignment Signal Signal Red video 9 * * Green video Digital Ground Blue video Ground Ground H-Sync Red ground V-Sync/VCL Green ground Blue ground Note * This pin is used for selftest detection. Connect this pin to ground at the PC end.

  • Page 8: Timing Chart

    VM77S 2-3 Timing Chart This section describes the timings that the computer industry recognizes as standard for computer-generated video signals. Table 2-2. Timing Chart Mode H. Dots 1024 1280 1024 V. Dots 1024 H-freq (kHz) 31.47 37.5 43.3 46.8 53.67 60.02...

  • Page 9: Power Saving Function

    VM77S 2-4 Power Saving Function Note: The monitor will be driven into “Power Saving” mode by the control signal from the display controller, as indicated by the amber-color power LED. Table 2-3. Power Saving Function State Power Consumption Light Normal...

  • Page 10: Operation Theory

    VM77S 3 Operation Theory This is a fully digital controlled multi-sync color monitor that is compliant with DDC1 and 2B Plug and Play VESA standard and offers the following main features. 3-1 Main Features 1. Simplified design with minimum components.
  • Page 11 VM77S 3-3-1 Horizontal Section 1. The oscillator is driven by the currents in R419 and R420. The minimum oscillator frequency is determined by R419 and the maximum frequency is determined by R420. 2. Horizontal sync goes into pin 15 through R318. And horizontal flyback pulse goes into pin 1 through R401 and bypass filter C403 from pin 6 of FBT and R496 for HFLB loop.
  • Page 12 VM77S Q433, R436, R497, R459, C482 to control I501 pin 22 voltage. When I501 pin 22 voltage drops below 4.1 V, the ABL function will happen. 3-3-8 H/V size breathing compensation 1. Beam current is sensed as above section (3-3-7 item 2) and this voltage routes through R451, R468, C470 then through R437 to I401 pin 31 for H.
  • Page 13 VM77S 2. Regulation The DC O/P voltage is proportional to the auxiliary voltage, so I801 pin 4 senses the feedback voltage from the divider D806, R809, C810, VR801, Q803, Q801 and R821 to compare with the built-in 1.5 volts reference voltage for error amplifier operation. Finally pin 6 can modulate the different duty cycle by VR801 setting to achieve regulation purpose.
  • Page 14 VM77S 3-6 OSD (On Screen Display) Circuit 1. The I504 MTV021-21 is OSD IC. The OSD signals are worked by positive vertical 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.

  • Page 15: Alignments And Adjustments

    VM77S 4 Alignments and Adjustments This section of the service manual explains how to make permanent adjustments to the monitor settings. 4-1 General Adjustments 4-1-1 Adjustment Conditions a) Power Supply Apply AC 115 V or 220 V b) Warm-up Time The monitor must be powered on for 15 minutes before starting any alignment, but requires 30 minutes of warm-up time for convergence adjustment.

  • Page 16: Alignment Procedures

    VM77S 4-2 Alignment Procedures 4-2-1 High Voltage Adjustment CONDITION Press buttons simultaneously when switching the power “On”. Display image : No video (68.68kHz Mode) PROCEDURE Connect DC meter to TP002 and adjust HV (icon) Obtain a DC voltage of -152.2 ± 0.2 V DC (Sampo FBT) or -153 ± 0.2V DC (LCE FBT) for CPT CRT M41AGE93X46 (TCO) or M41AGE83X46 (MPRII) .
  • Page 17 VM77S 4 Full white ABL setting CONDITION Display image : full white pattern Set Brightness to cutoff and Contrast to maximum. 4-b. Adjust ABL to Y=29.5FL ± 0.5FL. 4-c. Check the white balance at 5FL and 28FL. 4-d. Repeat all the procedures in 4-2-2 section until the best white balance is obtained.
  • Page 18 VM77S 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 the screen. 4. Rotate the pair of rings of 4-pole convergence magnets by maintaining spacing between the 2 tabs to converge the horizontal red and blue lines at the center of the screen.

  • Page 19: Troubleshooting

    VM77S 5 Troubleshooting 5-1 No Raster No Raster Measure voltage of B+ at T402 pin 2 on PWB-MAIN Normal High (68 V, 31.5 kHz) (75 V or more) Check voltage of Check I401, cathode, heater, I703, R719, C741, Short Circuit Grid 1, Grid 2, etc.
  • Page 20 VM77S 5-2 OSD Abnormal OSD Abnormal Check I502 pin 9, 4 Put on is 5V and pin 5, 10, 7, 8 I502 missing? Check R517, L514, R527, R523, R524 Replace them Check P502 Replace it Replace I502...
  • Page 21 VM77S 5-3 Function Key Abnormal Function Key Abnormal Put on Check I701 and I701, I703 I703 missing? Power ON/OFF again and Replace X701 check X701, oscillator Check Replace I703 or do I703 EEPROM content ATE again Replace I701 and check...
  • Page 22 VM77S 5-4 No Vertical Scan (Raster is one horizontal line) No Vertical Scan Check I301 voltage of Ckeck or replace pin 1 is 12V, pin 4 is I301. -12V, pin 2 is 35V? Check Check R312, R307, pin 5 O/P waveform at...
  • Page 23 VM77S 5-5 Out of Horizontal Synchronization Out of Horizontal Synchronization Check or replace Horizontal the signal cable or sync present at H. sync pin 41 pin 15 of I401 of I701. Check I401 pin 8 H. output Check or replace frequency &...
  • Page 24 VM77S 5-7 R.G.B. Video Amplifier Abnormal RGB Video AMP Abnormal Check Check or replace the waveform at I501 pin 5, 6 and signal cable or I501 Check I502 pin 1, 2 and 3 collector Check I901 voltage (normally about 70V) &...

  • Page 25: Recommended Spare Parts List

    VM77S 6 Recommended Parts List Note:1. The components identified by “ “ mark are critical for X-ray safety. Replace these with exactly the same parts specified. N o . Location Part Number Description Q 4 0 1 6 4 2 1 0 0 2 7 0 5...
  • Page 26 VM77S Location Part Number Description Q419 6422006000 TR NPN 2SD2012 TO-220(IS) Q420 Q421 6426010500 (S0) FET N-CHNL IRF630MFP/IRFS630A Q430 6426006400 (S1) Q451 6426006300 FET N-CHNL IRFS634A FAIRCH 11d R803 6203080017 POSISTOR & OHM DGC2R08M R804 6201100012 THERMISTOR 10 OHM 3A P=5 UEI...

  • Page 27: Block Diagram

    R DAC P501 G DAC B DAC RG R LM2479 GG G R, G, B I502 I501 BUFFER Video AMP & DC PRE AMP BG B LM2469 LM1267 RESTORE R G B SW 5 V 11.6V MTV021 P503 P502 BLANKING BRIGHTNESS CONTROL &...

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