Follow up: Re: Tech: G08

Hi all,

I replaced the TIP29B and that fixed it. Thanks Rodger!

Does anyone understand how the spot killer circuitry works on the G08 monitor?
 The Star Trek manual mentions it, yet I can't find the devices on the
schematics. Anyone?

On Jun 3, 2:55pm, Rodger Boots wrote:
> Subject: Re: Tech: G08
> The +9.1 volts comes through Q401. The +63 goes through
> R404 (220 ohms, 10 watts) to the collector of Q401 (TIP29B
> with a heat sink added). The +63 goes through R405 (8.2 Kohm,
> .5 watt) to the base of Q401 and also through D408 (1N914) to
> ZD401 (9.1 volts, .5 watt, 5% zener diode, a 1N5239B) to ground.
> This should put 9.1 + .6 volts (9.7 volts) on the base of Q401.
> You lose the .6 volts in the emitter-base junction of Q401 which
> leaves 9.1 volts at the emitter. C405 (10 uF, 25 volts electrolytic)
> filters the +9.1 volt output. C701 (47 uF, 16 volts electrolytic) also
> filters this line. And so does C905 (22 uF, 16 volts electrolytic) in
> the high-voltage supply.
>
> Look to see if the +9.1 volt supply is shorted to ground. Zero ohms
> could be one of those filters. 24 ohms or so could be a shorted
> C911 (100 uF, 16 volts electrolytic) in the high-voltage supply.
> Around 70 ohms could indicate a shorted Q902 (MPSU07) in the
> high-voltage supply.
>
> Does the +9.1 come back with the high-voltage supply unplugged?
>
> There is also a -9.1 volt supply formed by the -63 volts going through
> ZD402 (9.1 volts, 1 watt, 5%, no part number given) and filtered by
> C406 (10 uF, 25 volts electrolytic), C601 (47 uF, 16 volts electrolytic),
> and C904 (22 uF, 16 volts electrolytic) in the high-voltage supply.
>
>
> Mark Jenison wrote:
>
> > Hi all,
> >
> > I have two G08 monitors which I'm having trouble debugging.
> >
> > They both have known good HV units and known good deflection transistors.
 Both
> > of them sound like they are deflecting correctly, but no picture is showing
up,
> > and no HV is on.
> >
> > One seems to not be generating the 9.1V (is this AC, or DC?). Anyway, I
was
> > wondering if anyone knew which part was regulating this voltage. Is it the
> > TIP29B, or is it regulated by the HV, or by the custom chip in the
deflection
> > board.
> >
> > It amazes me that we have such good documentation on repairs of the WG6100
and
> > Cinematronics monitor, but there is no good repair guide for the G08. I
tried
> > to make one (or at least the template for one), but it needs more technical
> > meat from the gurus. See here:
> >
> > http://www.enteract.com/~jenison/mars/faq/G08.FAQ
> >
> > If anyone wants to contribute to the document, let me know. Thanks!
> >
> > ____________ ______ ___ _____ __ ____________
> > / __/ / / / |/ / / |/ //|/|/|_______________
> > Mark Jenison / __/ /_/ / / / | // | / |__ __/ _ /__ \ Sega/Gremlin
> > jenison@ /___/___/_/_//_/_/_/|_//__|/__| / / / // / / Color Vector
> > cig.mot.com /_/|_| /_/ /____/_/|_| Arcade Games
> > ____________ The One and Only 4-player vector game ____________
> > when the monitor is working
>
>-- End of excerpt from Rodger Boots
Received on Mon Jun 21 10:38:52 1999