[Curt Palme]

I know what you're all thinking, change the HV power supply.


I did, this did not cure the problem.


The problem is, no HV on this 1996 8500. I have:


Changed the LV and HV powers supplies with known working units.


Changed the H deflection with a known working module


Pulled the focus board (the set's HV will still fire up with the focus board pulled from past experience)


Replaced the vertical and convergence boards with known working ones from an 8110 which I believe are the same.


No error lights are on on the back, BTW.


Changed CPU boards


Pulled the quad decoder.


Disconnected each CRT socket and HV lead to see if a shorted tube was dragging the HV down.


It's now down to the motherboard or something weird.


Does anyone have the voltage that should be present at the HV connector that plugs into the motherboard? Or any other hints?


Thanks!


Curt

 

[Tim in Phoenix]

Say Curt


You could have a false HV inhibit coming from a neck board or the VIM; try unplugging the neck board multi-pin connectors one at a time; or try another VIM from the 8110. If the filaments light up for each tube then those should be okay. A long shot might be the deflection processor atop the control board.

 

[Curt Palme]

Thanks Tim, I did try unplugging the connectors from the PC board on the CRT cards one at a time.


Are you saying the RGB board can cause a HV shutdown? that's about the only board I did not try...


Got your message on the panel; I'm putting together a list of parts I need from you and will email you shortly.


Thanks!


Curt

 

[Tim in Phoenix]

Say Curt


Some protection circuits are situated on the vim, not a common problem but a possibility. I hope you don't have a bad backplane; that would be tough to replace.

 

[Curt Palme]

Thanks, I'll try that. I have the schematic now so I will go thru it and check voltages, etc.



Curt

 

[JoyMan]

Have you checked the Video Neck Board ?

 

[M NEWMAN]

Deflection processor bd on the CLM is a very real possibility, Curt. Swap that (or the whole Assy).