Service manual

Method 2 (with oscilloscope)
1. Connect the RF output (channel 3) of the pattern generator to the antenna input
of the TV. Test pattern is a “black pattern” (blank screen on CRT without any
OSD info).
2. Set Normal Red, Normal Green and Normal Blue to 32.
3. Set contrast to 0 and brightness to a minimum (with OSD still visible).
4. Set the channel of the oscilloscope to 50V/div. and the time base to 0.2ms.
Select “external triggering” on the vertical pulse (pin 1 of optocoupler 7610,
located near connector 0325 to frame deflection coil).
Caution: be aware that the frame deflection is “hot” and CRT circuit is “cold”.
1. Measure the black level pulse during the vertical flyback (1st full line after the
frame blanking) at the R, G, and B cathodes of the CRT (pin 8, 6 and 11 of the
CRT socket). Select the cathode with the highest VDC value for adjusting.
2. Adjust this gun with the Vg2 (SCREEN) potmeter of the LOT to 160V ± 2VDC for
the 27 inch sets and to 165V ± 2VDC for the 32 inch sets.
Figure: Waveform Vg2 alignment