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 13 21:58:04 2013
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