Re: Star Wars OVERVOLTAGE

I've gone over the overvoltage section 3 times now and haven't found
a problem. All my regulator voltages look good, every part I can
test or swap has been tested or swapped.

I am looking at the second revision of the overvoltage schematic
which matches my board. This is simplistic, but after studying the
schematic it appears to me that voltage is sent from Pin 4 of the
focus block into transistor Q5 2N3904.

Q5 looks like the key (sole?) determination of an overvoltage
condition, am I right? If overvoltage, it 'switches' to the LED CR2,
which continues on through Q4 MCR100-3 rectifier which then shuts
down the HV. In-other-words, the very first path from Q5 is the LED
itself.

Since my LED is on, AND the voltage is getting cut, doesn't that mean
that Q5 has indicated that there IS an overvoltage condition and so
everything "downstream" from there such as Q4, etc. is working
properly?

So basically, if the LED is on, then either Q5 is bad, something
related to the focus block Pin 4 line is bad (such as the R17 20K
pot) causing it to "report" an incorrect voltage to Q5, or else there
really IS an overvoltage condition.

Is there a way I can measure the actual voltage at Pin 4 of the focus
block and/or the voltage at Q5 to see what is actually happening?

And if it really is overvoltage, what possible reasons could cause
this to happen?

Remember, this is a brand new Wintron HVT, that replaced my previous
Wintron HVT that was working fine for over a month, then failed,
accompanied by internal arcing noises. At the same time the previous
Wintron failed, that is when the overvoltage LED came on. And now
even with the new Wintron, the overvoltage LED won't go off.

Thanks everybody, I hope we can solve this problem so this thread
might help somebody else in the future!

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Received on Sun Mar 28 01:48:32 2004