Re: Battlezone Half Screen, 1N270 diode on X center?

-----Original Message-----
From: MKDUD@aol.com
To: vectorlist@synthcom.com
Date: Sun, 23 Feb 2003 21:11:39 EST
Subject: VECTOR: Battlezone Half Screen, 1N270 diode on X center?

>
> Hello,
>
> I have a Battlezone AVG board that boots up fine and passes self-test.
> After replacing several dacs, the board was working fine. Now, the right half
> of the screen is missing, and I know the problem is not monitor related. The
> rscreen was fine, and the right side just started gradually fading out, and
> now just the left side is there. (these pics are big):
>
> http://members.aol.com/mkdud/BZ/bzhalf.jpg
>
> I just noticed that another working BZ AVG board that I have has a 1N270
> diode that goes from where the X Center pot would be (kathode) to ground
> (anode). Does anybody know what this diode does? The board that only shows
> half of a screen does not have the 1N270, and it looks like it never did.
> When were these added, and what for?
>
> http://members.aol.com/mkdud/BZ/xctr1n270.jpg
>
> Also, why do some boards have mylar caps attatched to pins 1 and 2 of
> the TL082s?
>
> Please help if you can,
> Thank You,
> Michael Kelley
>
>

the caps are probably to reduce noise, but be suspicious of mylar - they do change value and fail.

interesting diamond-pattern, never seen that before!

maybe check he highest(sign) bit on the horizontal dac?

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Received on Mon Feb 24 03:53:26 2003