Related Manuals for Toshiba 1997 G Series
Summary of Contents for Toshiba 1997 G Series
- Page 1 S E R V I C E T R A I N I N G 1997 G-SERIES COLOR TELEVISION POWER SUPPLY AND SHUTDOWN TROUBLESHOOTING GUIDE...
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Page 2: Table Of Contents
Contents POWER SUPPLY CIRCUIT ........1 1. OUTLINE OF SYSTEM ........................2 2. STAND-BY POWER SUPPLY ......................3 3. MAIN POWER SUPPLY ........................3 4. OUTLINE OF THE CURRENT RESONANT TYPE SUPPLY ............. 4 5. FUNDAMENTAL THEORY OF LC SERIES RESONANT CIRCUIT ........4 6. -
Page 3: Power Supply Circuit
POWER SUPPLY CIRCUIT... -
Page 4: Outline Of System
1. Outline of system The block diagram of the power supply is shown in Fig. 1. The N7 chassis consists of the standby power supply which supplies power to the microcomputer, and the main power supply which supplies power to the hori- zontal output and audio output. -
Page 5: Stand-By Power Supply
3. Main Power Supply 2. Stand-by Power Supply 1. Main Power Rectifier Circuit The stand-by power supply supplies 12Vdc to the re- lay SR81, 5V to the microprocessor, 5V to the protect D801 and C810, the rectifier and filter for the main IC, and a reset 5V to the microprocessor. -
Page 6: Outline Of The Current Resonant Type Supply
4. Outline of the Current Resonant Type Supply The main B+ is regulated by negative feedback. The main B+ is fed into an error amplifier and outputted to a Fig. 3 shows the block diagram for the current resonant photo coupler. The output of the photo coupler is ap- switch mode power supply. - Page 7 STR-Z415, STR-Z415, and STR-Z4201 Block Diagram DRI Vcc START Logic DELAY LATCH CONTROL CONT Fmax Pin No. Symbol Function Half bridge power input Ground Dead time resistor terminal Oscillator capacitor terminal CONT Oscillator control terminal Maximum frequency determining resistor terminal Soft start capacitor terminal Capacitor for delay latch: ON-OFF terminal Power source terminal for control section...
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Page 8: Main Supply Actual Operation
6. Main Supply Actual operation 5.CD terminal (Pin 8) - Latch Delay Refer to Figure 7 diagram and waveforms. The Latch circuit shuts the power supply off (shut-down) when a fault is detected. Shut-down occurs by detecting 1. Start-up errors from the following: When power is applied to the set, a start-up pulse of •... - Page 9 Actual Circuit R861 (AC) C810 R862 D862 T862 D883 R810 MAIN OUTPUT R871 D864 Q801 C868 C884 D884 START Z801 Q862 DELAY LATCH D875 C891 CONTROL C871 R891 D855 Audio CONT Fmax output C874 R866 R864 C866 R868 C867 R870 C870 D886 C869...
- Page 10 Voltages On IC801 Using a 100 W light bulb as a Losd Voltage Voltage 150 Vdc 17.7 Vdc 0 Vdc 7.8 Vdc 5.8 Vdc 0.9 Vdc 2.3 Vdc 0 Vdc 5.8 Vdc 5.8 Vdc 75 Vdc 3.6 Vdc 83 Vdc 0.4 Vdc Fig.
- Page 11 Power Supply Troubleshooting Guide. Push power button Does the relay engage? Check: Sub Power supply, Microprocessor Does the TV go into and Relay drive circuits shutdown? Open pin 3&4 B+ to low of Q862 Is the B+ at F470 Low or at 0v? If 165V and Start up are present.
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Page 12: Main Power Supply Troubleshooting Guide
7. Main Power Supply Troubleshooting Guide Poor Regulation: The Main Power Supply is a looped circuit. In order to troubleshoot the circuit, the loop must be broken. By interrupting the feedback portion of the loop, it can be determined if a problem exists in the primary or second- ary side of the supply. - Page 13 No Start-up: To prevent IC801 from going into over-voltage protect during start-up, the charging of C869 will temporarily A failure in one of the sub-circuits on the primary side disable the latch. When a DC voltage is applied to the of the power supply can prevent IC 801 from switching cap, it acts like a short and it disables the latch.
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Page 14: Scan Driven Supply
8. Scan driven supply The flyback transformer develops a scan driven supply (T461), shown in Fig. 11. The Flyback supplies 200V for video output from pin 3, 27V for vertical output from pin 6, -27V for side DPC from pin 5, and 12V from pin 7. - Page 15 NOTES...
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Page 16: Sub Power Supply
19” TVs and is similar in operation to current in the secondary winding, and induces a potential the supplies used in Toshiba’s VCRs and DVD players. on the detection winding which continues to hold Base of Q1 low. - Page 17 160V IC 802 R846 Q852 C845 R852 R859 C856 C850 D855 Q851 C851 D848 C849 C852 L851 R847 D849 D847 D850 R858 C855 R851 C853 R850 D856...
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Page 18: Sub-Power Supply Troubleshooting Guide
11. Troubleshooting Sub-Power Supply. Refer to fig 14. To troubleshoot the Sup-Power Sup- ply, it must be isolated from the load. It is necessary to hookup an external load to the secondary, and use a Variac. With the Variac set to 40 Vpp and a 100W light bulb hooked up for a load, the relay has to be shorted to supply the 40Vpp to the Sub-Power supply. -
Page 19: Shut Down Circuits
SHUT DOWN CIRCUITS JRS 12-97... -
Page 20: Summary Of Shut Down Circuits
1. Summary of Shut down circuits. X-ray Protect. The X-ray protect is connected to pin 13 of Z801. Z801 compares this voltage to the reference voltage on pin 11 Figure 14 is a block diagram of the eleven shut down (aproximately 25 volts). - Page 21 Figure 14. Summary of Shutdown circuits. JRS 12-97...
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Page 22: Power Shut Down Troubleshooting Guide
2. Power shut down troubleshooting guide. JRS 12-97... -
Page 23: Volt Over Voltage Protect
Normal voltage at the monitor point is about 0. A volt- 3. +30 Volt Over Voltage Protect. age of about 2.5V or greater will result in shut down. When the supply voltage goes beyond the zener votage, the zener diode conducts and delivers a voltage to the anode of D 863. -
Page 24: Over Current Protect
R 7782 will turn on Q768. The collector then goes to 5. +30 V Over Current Protect. about 30V. This is the monitor point for shut down. Resistor R 7782 is the Sensing Resistor. It is a very The normal collector voltage is Zero. small value. -
Page 25: 15V Over Current Protect
7. -15V Over Current Protect. The -15V over current protect operates in a manner simi- lar to the +15V over current protec circuit. Figure 19. -15V Over Current Protect. 8. +35V Over Current Protect. When Q370 turns on, the collector will go high, towards A +35V source is developed at the cathode of Diode the +35V supply. -
Page 26: 15V Under Voltage Protect
The -15V turns on transistor Q854. This causes the col- 9. +/-15V Under Voltage Protect. lector of Q854 to go to about -15V. If the -15V goes The two circuits work independantly, and do not affect low, Q854 will turn off, the collector will go towards the each other. -
Page 27: Under Voltage Protect
When the 200V drops to about 160V, Q340 turns off, 10. 200V Under Voltage Protect. and Q341 will turn on. When Q 341 turns on, its collec- The flyback transformer T 461 produces about 200V at tor voltage will go to about 6 V, sending the high to pin the cathode of D406. -
Page 28: 125V Over Current Protect
During normal operation, the voltage drop across R470 12. +125V Over Current Protect. is approximately 0.5V. The turn on surge voltage drop The current sensing resistor, R470, is in series with the is approximately 1.5V. +125V supply. If the voltage across R470 exceeds about 1.8V, shut down If the supply current exceeds a certain level, the increased will occur.