Re: Black Widow Video Problem

Thanks Douglas! That's an excellent suggestion about A/B11's output. I'd forgotten that detail…

I checked the resistors after I switched the chip/socket at C12 and looked at the voltages and chip activity with a probe afterward and it looked fine. A/B11 also seems to be making the right noises (with the probe) but I do know from experience that they can have strange effects as they die (had a Tempest once with a completely mirrored image and it was the 1495. )

The Y pot looks original. I'll meter it and see what I see. I get what appears to be y collapse or perhaps complete fold over if I adjust the pot too far in either direction. Within the small range of pot movement where there's no collapse, the Y image can be adjusted larger and smaller…if only a little bit. -M

On Jan 31, 2012, at 10:30 AM, Douglas Gauck wrote:

> It does look like a Y axis problem. My question was how the X correction coming out of A/B11, going into your new main Y axis C12 could affect the output.
>
> Since it's socketed, you can pull out C12 and then check all the resistors around it in circuit - all that voltage in the area could have toasted one.
>
> You should be able to adjust Y size from limit to limit without collapse. Or do you mean shrink?
>
> Since there's been prior work done on the board (and the pots are often abused) is it Y size the correct 10K?
>
> -Douglas
>
>
> On Jan 31, 2012, at 12:37 PM, Malcolm Mackenzie wrote:
>
>> Thanks Douglas.
>>
>> The MC1495 at C12 has been socketed and replaced by me. That chip had been socketed before, but the contacts were shorted under the socket. I replaced the socket and chip and that's how I got the video to come up. I haven't replaced C11 as this problem appears to be in the Y channel, but I'll check into it.
>>
>> As far as I understand the pincushion correction 1495s won't cause this problem. I'll try to piggyback a new one on them to make sure.
>>
>> One added note. I've noticed that the y-size pot has only a very narrow range of adjustment. Too small and I have y collapse, too large, and y collapse. In the very middle of adjustment the pic stretches out to as it appears in the pictures I posted. Don't know if this helps anyone pinpoint it. -Malcolm
>>
>> --- On Tue, 1/31/12, Douglas Gauck <douglas@gauck.com> wrote:
>>
>> From: Douglas Gauck <douglas@gauck.com>
>> Subject: Re: VECTOR: Black Widow Video Problem
>> To: vectorlist@vectorlist.org
>> Date: Tuesday, January 31, 2012, 5:49 AM
>>
>> The caps are just sauce for the goose; I'd say the next likely cause is one of the MC1495Ls... at C12. I'm not up to speed on how the others (A/B11 and A/B12) providing X and Y correction factor in.
>>
>>
>> On Jan 30, 2012, at 11:19 PM, Maxstang wrote:
>>
>> > Thanks for the reply. TL082s have been checked and one replaced with no change. Voltages are good, but I haven't replaced the caps yet.
>> >
>> >
>> > On Jan 30, 2012, at 8:09 PM, Douglas Gauck wrote:
>> >
>> >> TL082 at D10 and/or D/E12?
>> >>
>> >> Also check the +/-15v and 6.8 volt supplies, and maybe give them new caps?
>> >>
>> >>
>> >> On Jan 30, 2012, at 8:42 PM, Malcolm MacKenzie wrote:
>> >>
>> >>> Hi all. I've been working on a dead BW board and now have it at least showing video, but it's still distorted. AVG chip and socket, and vector RAM and socket are good. Anybody seen this before? It almost looks like vertical fold over and the image does expand and contract along the y axis. Self test video is similarly distorted but I don't get any reported errors other than pokey problems. Any input is appreciated. -Malcolm
>> >>>
>> >>> Photos are here:
>> >>>
>> >>> http://i122.photobucket.com/albums/o263/maxstang289/IMG_2612.jpg
>> >>>
>> >>> http://i122.photobucket.com/albums/o263/maxstang289/IMG_2611.jpg
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Received on Tue Jan 31 14:35:50 2012