Star Wars OVERVOLTAGE

Here's the "short" version of my nightmare:

Followed Michael Kelley's HV/Delflection FAQ to the letter -
completely rebuilt HV & deflection boards with all mods.

At that time installed brand new Wintron HVT.

Game worked perfectly for just over a month, then no picture,
overvoltage LED on, accompanied by a crazy arcing noise inside the
Wintron.

I figured it was something I did because Wintrons never fail. So I
started checking voltages and components, and everything looked fine.
 Finally I pulled 1 leg of CR1 to disable the overvoltage circuit.
The Wintron arcing noise went ballistic, but I was able to measure
appropriate +24/-24 and +30/-30 voltages at all the test points.
Only problem was no HV along with the noise. So I finally decided
the Wintron itself must be the problem and returned it.

Wintron sent me a brand new HVT (thank you Wintron). I just finished
hooking it back up to the board. When I turned it on, everything
seemed fine. The picture looked fine, the brightness was great, R7
and R17 were in the same positions as when previously working, yet
all voltages looked good without adjustment - I measured B+ of 180V
at the anode side of CR3.

But wait, I've forgotten to solder the pulled leg of CR1 back in. So
I did that, powered it back up, and DOH! The overvoltage LED is on!
The HV is completely shut down.

I thought Wintron HVTs wouldn't put out too much voltage? Of course
I have tried every possible position of R7 & R17 with no effect.

Why is the overvoltage circuit activated?

I pulled CR1 again to do another voltage test. The HV turned back on
like it should with CR1 out. Now, I don't have a HV probe, but I've
read the R7 adjusts the HV and B+ simultaneously, so if you are
reading +180V at the anode side of CR3 then everything should be fine
on the HV side. I am reading +180.0V. Every test point shows
perfect voltage.

But touch CR1 back in and the HV shuts down, LED comes on.

I read in the FAQ that somebody changed R6 from 3.9K to 2K to
decrease the HV, but it also says "he is referring to a Penn Trans
HVT. Odds are if you are using the WinTron you might not see this
problem".

What am I doing wrong?

Thanks everybody!

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Received on Thu Mar 25 11:46:49 2004