Re: Battlezone - intermittent graphics glitch

I had previously replaced both BIP pots.

Q2 and Q3 tested good both in and out of circuit. Since they're
trivially cheap, I went ahead and just replaced both.
I then swapped out the DAC-08, and now the board is working fine!

Thanks for the advice.

Alan

On 4/13/2013 8:57 PM, Douglas Gauck wrote:
> If you look real close it seems to be both X and Y. Maybe the components responsible for the BIP and/or XY reference levels (DAC-08 at C9, Q2, Q3, etc)? You got the BIP pots, too?
>
> Persistent should make it easier to find, so that's progress... right?
>
> -DrG
>
>
> On Apr 13, 2013, at 7:30 PM, Total Impulse wrote:
>
> >
> > I've finally had time to look at this Battlezone pcb again, but I'm not making any progress in fixing it. The graphics glitch is getting worse; it's now persistent rather than intermittent.
> >
> > To be thorough, I installed new vgrom sockets at A3 & B/C3. I also tried swapping those two ROMS out for a different set. No difference.
> >
> > I wondered if the problem was in the Y output circuitry. I tried swapping out the DAC at D9 and the LF13201 at E10. I also replaced the TL082 at D10. No difference. I checked through most of the components in the Y-output path without finding anything that was obviously bad.
> >
> > Any new ideas, anyone? Other than diving headlong into the vector generator?
> >
> > Thanks,
> >
> > Alan
> >
> > On 2/16/2013 3:08 PM, Colin Davies wrote:
> >> I'd look at the counters/timers and other maybe logic in the vector generator...
> >>
> >> Not sure if a Dodgy Eprom Sockets in the VGROM would cause that...
> >>
> >> I've got an Asteroids that slopes up like that too.. Not had a chance to look at it !!
> >>
> >> Regards, Colin
> >>
> >> ----- Original Message ----- From: "Total Impulse" <totalimpulse@comcast.net>
> >> To: "vectorlist" <vectorlist@vectorlist.org>
> >> Sent: Saturday, February 16, 2013 6:18 PM
> >> Subject: VECTOR: Battlezone - intermittent graphics glitch
> >>
> >>
> >>>
> >>> I'm working on a Battlezone board set. It has an intermittent graphics glitch - lasts anywhere from a fraction of a second to a few seconds in duration at random intervals. When it goes "wonky", the vector endpoints in text spread apart and the lines of text angle upwards and become distorted.
> >>>
> >>> Photos here:
> >>> https://picasaweb.google.com/108339843851140624101/BZIssue#
> >>>
> >>> Before I start digging into it, any suggestions on likely areas to check first?
> >>>
> >>> I've already replaced all the electrolytic caps, the adjustment pots, the header pins for the interboard cable, and any obviously poor condition sockets. No faults come up in self test mode.
> >>>
> >>> Thanks,
> >>>
> >>> Alan
>

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Received on Sat Apr 20 18:21:03 2013