Re: Amplifone HV board

In a message dated 98-09-30 15:25:33 EDT, you write:

<< I came across a Star Wars the other day. It has the new HV unit installed
 (Penn Tran, Wingate, PA). I hear deflection chatter, and it sounds like HV
is
 coming up, but its possible it's shutting down again immediately, because
 there's no heater glow, and I can't seem to discharge the tube.
 
 What does the red LED on the HV PCB indicate? It is currently lit.
>>

This is your HV overvoltage protection curcuit. You need to reset the curcuit
- This is done through VR17 and VR7 on the HV board. You'll need a HV probe.
By the book:

1. Remove power from the display
2. Attatch the negative lead of your HV probe to the DAG spring.
3. Connect the HV probe to the anode (under anode cap) on the CRT, and make
sure your meter is set to DC volts.
4. Turn power on to the display.
5. Rotate VR17 to its fully counterclockwise position
6. Rotate VR7 until you get a reading of +25kv on the meter.
7. SLOWLY rotate VR17 until the voltmeter reading drops to 0.
8. Turn the display power off for 10 seconds, and then turn it back on. This
resets the over-voltage protection curcuit.
9. Readjust the frequency (VR7 )until the voltmeter reads 19.5 kv.
10. Remove power from the display and then remove the HV probe from the anode
and DAG spring connection.

Hope this helps,
MK
Received on Wed Sep 30 16:00:16 1998