Re: TECH: Major Havoc

The distortion is analog looking (not edgy like digital) so it must be
something from the DAC's outward. The easiest thing to check first are
ALL power supply voltages in the analog section. Did this happen
suddenly? Were you swapping board? Spilled Beer? :-)

If you have a scope try looking at the signal directly after the DAC
op-amps and before the other analog IC's perhaps.

jess

Steve P. wrote:

>
> Well, following Joe B's advice, I bypassed the X & Y OUT signals by
> pulling the connections from my Tempest harness and jumped them to the
> X/Y OUT pads on the main PCB. The board is still not working although
> the pattern on the screen changes a slightly but it's still a bunch of
> scrambled jumbo that reminds me of an EKG. :)
>
> I've reached the limit that I am willing to tinker with the PCB - who
> repairs these that can do so in a timely manner?
>
> Thx.
>
> -Steve P.
>
>
> ----- Original Message ----- From: "Joe" <joe@joesarcade.com>
> To: <vectorlist@vectorlist.org>
> Sent: Tuesday, January 04, 2005 3:52 PM
> Subject: RE: VECTOR: TECH: Major Havoc
>
>
> Yep, no can do.. Maybe Clay was just mistaken or looking for more
> repairs :)
>
> You can still use your scope on the test points on the board to see
> the image... Or, pull the X and Y signals from the harness and
> alligator clip them to the points on the boards. You will get an image.
>
> IMHO for your problem, I would most likely start tracing your X and Y
> back to the outputs from the dac with a scope (actually first opamps.)
> I think you may find that you have a bad DAC or something broken on
> the digital side. Tough to say though.. First use your scope.
>
> A certain Space Duel board comes to mind that had a similar problem
> and I believe I found a bad DAC in combination with a LF13201. IIRC of
> course, that was years ago.
>
> JB
>
> ________________________________
>
> From: owner-vectorlist@vectorlist.org on behalf of Steve P.
> Sent: Tue 1/4/2005 12:13 PM
> To: vectorlist@vectorlist.org
> Subject: Re: VECTOR: TECH: Major Havoc
>
>
>
> Thanks for the reply. I thought that it sounded odd plugging MH into
> SD w/o
> an adapter, thus the post. :)
>
>
> -Steve P.
>
>
> ----- Original Message -----
> From: "Tom McClintock" <tomm@mgcap.com>
> To: <vectorlist@vectorlist.org>
> Sent: Tuesday, January 04, 2005 12:55 PM
> Subject: Re: VECTOR: TECH: Major Havoc
>
>
>>
>>
>> Steve P. wrote:
>>
>>>
>>> Is it possible that the Tempest adapter card might have a bad chip? I
>>> know it controls the pincoushining, but is there more to it than that?
>>
>>
>> The adapter PCBs only do two things as you have noted - remap the
>> pinouts
>> and provide pincoushion correction.
>>
>>
>>
>>> Also, can I plug the MH PCB into a Space Duel harness w/o the adapter
>>> card as a way of testing? I searched Dejanews and Clay Cowgill
>>> mentions
>>> that you can plug the MH into a SD harness with no ill effect.
>>
>>
>> Uh, you can take a quick look a thte pinouts for each and see that the
>> video outputs on Major Havoc are quite different than either Space
>> Duel or
>> Gravitar. So, I would say no to this question.
>>
>> Here are some details on the conversion PCBs that I cobbeled together
>> earlier this year:
>> http://www.ionpool.net/arcade/mh/major_havoc_conversion.txt
>>
>>
>>
>> tm
>>
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>>
>
>
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Received on Wed Jan 12 01:28:17 2005