Re: G08 Star Trek with no HV

Yes, no voltage indicates trouble in the X deflection. If you hear
deflection chatter, you should have enough signal to display something
on the monitor. Usually the HV unit will still fire up with one side of
the deflection collapsed.

Some things to check:
Cold solder joints, especially on the connector, HV transformer pins,
and T900. Reflow them even if they look good.
Check for approx. 100v coming out of the little HV board. Measure the
end of R307 nearest the screw hole.
Check Q900 (would it still be called the HOT?)
If so far, so good, then you need to start probing the oscillator
circuit. May be hard to do without a scope. Start with Pin 9 on the IC.
If there is no signal at pin 9, then the IC is probably bad. Before you
chuck it, fix the X section and retest.

If you have oscillation at pin 9, follow the signal through Q901, Q902
(on the back of the board), and Q903. Next stop is the end of R327
nearest the coil. Last stop is the Collector of Q900 (yellow wire, I think).

If you have oscillation up to the HV transformer, 100v feeding it, and
no cold solder joints, then the last suspect is a bad HV transformer
(highly unlikely).

Hope this helps.
Hans O in Chicago
(If you get totally stumped, I can probably look at it for you.

Jeff Klammer wrote:
> Greetings. I just acquired a Star Trek with no picture on the G08
> monitor. You can play the game blind and with the back cover off, you
> can hear vector chatter. The high voltage doesn't seem to be coming on.
> Here's the voltage readings on the 10 pin to the HV board.
>
> 1. Approx +2.4VDC
> 2. No voltage
> 3. -9VDC
> 4. +9VDC
> 5. GND
> 6. GND
> 7. No Voltage
> 8. 118VDC
> 9.
> 10. No Voltage
>
> I've done some initial troubleshooting on the G08 chassis (installed Bob
> Roberts kit), but I don't find any bad parts yet. Can I assume that no
> voltage on pin 2 means that the problem is in the X part of the
> deflection board? This is my first time troubleshooting a vector
> monitor. I'm hoping to find someone in MN with a good Star Trek or G08
> vector game so I can narrow down the problem to the Star Trek hardware
> or the G08.
>
> I have read all of the archives and found one similar problem from Dec.
> 27 of 2005, but it looks like that problem was never solved (or at least
> never posted a solution). I've posted this on vaps.org also, but so far
> have not found the solution. I should have my scope up and running in a
> week or so which may also help troubleshoot.
>
> Thanks,
> Jeff Klammer
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Received on Fri Dec 29 19:13:54 2006