New Life Games LLC
Monitor Repair Log and Database. **Arcade and Gaming** => LCD and CRT Monitor Repair Tech Support => Topic started by: Badbaud on July 26, 2018, 10:13:04 PM
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The 6.3V from the main power supply does two things.
1. Provides voltage to the tube "heater".
2. is regulated by a 5.1V dc Zener to drive the 74HC86 vertical and horizontal buffer's Vcc.
All of the other DC voltages from the power supply read within limits, except the B+ voltage reads 88 Volts, it should be 125V.
The 6.3V output is the exception it is pulsing on and off slowly.
I removed the 6.3 line that went to the Zener circuit for the 74HC86 chip and the 6.3V still pulsed.
When I unplugged the 902 connector from the main board to the neck board the pulsing stopped and the 5V Zener circuit was stable at 5V.
The schematic only shows the heater being powered via a connector from the main board to the neck board #902.
If it is just the heater that is causing the over load problem, what does this say about the tube, or is there something the schematic is not showing.
Could the 6.3V be used to power the color amps on the neck board or some other circuit that has failed?