Tempest image taller on left side

Paladin

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Oct 10, 2008, 12:56:19 PM10/10/08

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OK, I've tried 2 different WG6100 monitors and the problem shows on
both. The left side of the screen is taller than the right. Other
than that, the picture seems great. I've tried adjusting the BIP
pots, and they don't correct the issue. I metered the pots, and they
checked OK. I reflowed the solder on all the interconnect pins.

Anyone have any ideas on what would cause this issue?

I took a picture of the crosshatch screen:
http://home.comcast.net/~dark.paladin/tempest3/images/tempest.jpg

ajcrm125

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Oct 11, 2008, 10:47:39 AM10/11/08

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Looks like your yoke could need adjusting.

Paladin

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Oct 11, 2008, 4:38:08 PM10/11/08

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I think that if it was the yoke, the entire image would be twisted.
It's only the left side that's taller, and I got the same results from
2 different monitors. At this point I think I may try a new big blue,
and a cap kit on the ARII. If that doesn't get it I guess I'll have
to start guessing. From what I've googled, I may have a 1495's in the
vector area of the board going out.

James Sweet

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Oct 11, 2008, 8:02:05 PM10/11/08

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I really doubt the distortion is anything to do with the power supply.
The jitter *could* be, but I think that's unlikely too. I've yet to
actually have a big blue cap fail in any of my games, those were pretty
well made.

paladin-ng

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Oct 11, 2008, 10:16:16 PM10/11/08

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Doest tempest have a special pincusion correction circuit consisting
partially of 2 the the MC1495L chips near the X/Y adjustment POTS.
would perhaps adding a little small pot allow for minute adjustments
of this help any?

I'm not actually suggesting this, more "pinging" the monitor type guys
for some input?

-brian

Matty-t

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Oct 11, 2008, 11:36:40 PM10/11/08

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The 1495's provide math functions to correct. When one goes bad, you
see what is pictured basicly. I would have replied sooner, but I
wanted him to actually /search first as it's been brought up more then
once.

- Matt

Steve Prendergast

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Oct 12, 2008, 3:45:53 AM10/12/08

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On Oct 11, 11:36 pm, Matty-t <mspy...@gmail.com> wrote:

>
> The 1495's provide math functions to correct. When one goes bad, you
> see what is pictured basicly. I would have replied sooner, but I
> wanted him to actually /search first as it's been brought up more then
> once.
>

> - Matt- Hide quoted text -
>
> - Show quoted text -

The Google Usenet search has been "iffy" at best lately to the point
that it's almost worthless.

Paladin

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Oct 12, 2008, 1:59:54 PM10/12/08

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On Oct 12, 12:45 am, Steve Prendergast <stevenprenderg...@gmail.com>
wrote:

Believe me, I've been searching. I found references to bowing and the
1495's, but the descriptions didn't exactly match mine with just the
left side being affected. I read that you can 'piggy-back' a new chip
on top of the old one to find which one is bad. I guess I'll add a
chip to my Bob Roberts order!

Scott Caldwell

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Oct 12, 2008, 7:36:24 PM10/12/08

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I had this issue on my Tempest board and one failed 1495 was the
cause. You really should replace them in pairs (I did) and the
problem was immediately gone.

Scott C.

Paladin

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Oct 12, 2008, 8:31:17 PM10/12/08

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Since my problem is on the X side, I'm guessing I should do both chips
in the X area. Is that right?

James Sweet

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Oct 12, 2008, 10:00:14 PM10/12/08

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Paladin wrote:
> Since my problem is on the X side, I'm guessing I should do both chips
> in the X area. Is that right?

Keep in mind that X on the game board drives Y on the monitor and vise
versa since the monitor is mounted sideways.