Re: Bulletproof your WG6100!

Someone wrote: (long thread, this)
...
> >>limit circuit, that could easily be added to the power transistors. I'll
> >>add it to my list of things to do when I am done with the fab order.
> >
> >I think it's more trouble than it's worth. The best I can tell voltage
> surges
> >seem to be the culprits that kill the X/Y transistors, not too much
> current. I
> >believe current wise the transistors are highly overrated, yet they still
> die.
...
Hi, All!

Based on over twenty years of service experience I believe that the
problem with the output transistors dying is not the regulation but the
main logic board providing too large a signal for the output
transistors. You will notice that the schematics call for a 2N2792X for
the horizontal range, the "X" is for eXtended range on the transistor. I
have noticed that Electrohome monitors for Star Trek seemed to die, and
I experimented with installing a switching supply on a few games, and
NEVER had a monitor fail after that! These games are still running, in
fact I sold one to a fellow in Japan last fall-it was installed in a
Nutting Computer Space cabinet (did this fifteen years ago) and the game
never had service since installation. The factory also made a XY input
limiting board that is in my games that refuse to die. (Note this
doesn't help the HV!)
I was thinking that for any future games we sell that we put both a
switching supply in AND a relay that will cut power to the monitor IF
the switching supply goes down. A simple 12 volt relay connected to the
+12 output should be fine, either that or hook up a 6V relay to the +5,
and if the +5 gets too low the relay drops out... A solid state relay
might be better...
Comments?
John :-#)#

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