Memorex MT1191V, Service Manual

Page: 7 / 23

INSTALLATION AND SERVICE INSTRUCTION
- 6 -
CAUTION:
Use an isolation transformer when performing any service on this chassis.
SHUTDOWN CIRCUIT:
When the high voltage rises, there are simultaneous voltage increase
developed at terminal 6 of the Horizontal Output Transformer ( T671 ) and applied to pin 29 of IC301. If
excessive high voltage is produced, the increased voltage developed exceeds the rating of zener diode
D552 causing the Horizontal Oscillator to stop functioning and the high voltage system to shut down.
AFT ( AUTOMATIC FINE TUNING ) ADJUSTMENT
1. Remove JP200. (See Figure 1 for positioning)
2. Connect positive wire of TV signal Generator (NTSC signal, 45.75MHz, 80dBu ) to JP199 and
negative wire of TV Signal Generator to TP4.
3. Connect wire (+) of DC Digital Voltmeter to TP6 and wire (-) to TP4.
4. Adjust T202 so that the DC Digital Voltmeter reading is 2.5V
±
0.2V.
5. Re insert JP200 and put solder.
FIG. 1
SUB TINT ADJUSTMENT
1. Connect TV Test Pattern Generator (NTSC signal, Color Bar signal, 70dB u , channel 6) to EXT.
Antenna Terminal (TE1) through TV Channel Signal Generator.
2. Connect positive lead of Oscilloscope to TP14 and negative lead to TP10.
3. Connect EXT. trigger of Oscilloscope to R463.
4. Set Tint control to center position. (by Remote Control).
( NOTE: For steps 5, 6 and 7 below, refer to page 3 for Adjustment By Remote Control Method).
5. Go to Adjustment Mode (1) by remote control.
6. Select SUB TINT from Adjustment Mode (1) menu screen.
7. Adjust SUB TINT level (by using + or - button on remote control) so that waveform is the same as
shown in Figure 2.
FIG. 2