Re: Black Widow Video Problem

If you have a scope, you could connect it in X-Y mode right to the 6012 DAC chip outputs (pin 18) and see if the image
looks okay there. If yes, then try again after the B10/E10 switches just before the 1495's. The idea here to narrow
down which section to focus on.

Bill Boucher

>
>
> 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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>
>
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Received on Tue Jan 31 15:48:37 2012