Re: Asteroids G05-801. Perfect picture for 5 mins then a circle appears in the middle of the screen.

Replace C510.

I've been staring at the schematic for a 1/2 hour and it doesn't make sense
that the spot killer LED is on but you have a picture. That means that the
problem is likely intermittent (repeating at some frequency too fast for the
eye to see). If C510 is losing its ability to provide the proper time delay
for the SK circuit, then maybe the LED is not really on all the time, but
just partially or flashing fast enough to look like it's solid on.
Similarly, Q503 may be misbehaving due to the bad C510. Who knows, maybe
it's causing the center dot. A scope trace from D506 cathode would likely
reveal much.

I recommend also, since you are going to be in there anyway, replace C508
and C509 since they are the same type and age. If C510 has failed, then you
might as well hit them all. Also, the diodes D504, D505, D506 (1N914 or
1N4148) might as well be replaced. They are super cheap and easy to replace
so you might as well change them just to be 100% sure that they are all
switching properly and not leaking or something. A shorted D505 would cause
strange things to happen.

William Boucher
http://www.biltronix.com

----- Original Message -----
From: "Brien King" <spammehere@arcaderestoration.com>
To: <vectorlist@vectorlist.org>
Sent: Thursday, February 09, 2012 11:18 AM
Subject: VECTOR: Asteroids G05-801. Perfect picture for 5 mins then a circle
appears in the middle of the screen.

> Ok, I have an Asteroids with a G05-801 in it. When the game is first
> turned on, the picture is perfect.
>
> However, the Spot Killer is on, and after about 5 minutes, a circle and
> dot show up in the center of the screen.
>
> http://www.arcaderestoration.com/graphics/repair/AsteroidsCircleInMiddle.jpg
>
> I capped the monitor and here is what has been replaced so far in the Spot
> Killer section:
>
> Q503
> Q506
> R518
> R528
> R529
> R523
> R524
>
>
> Any help would be greatly appreciated!
>
>
> --
> Brien King
> spammehere@arcaderestoration.com
> Visit the Arcade Restoration Workshop @ http://www.arcaderestoration.com
> Home of Cart Commander, the Ultimate Cartridge Cataloging Utility!
>
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> ** Please direct other questions, comments, or problems to
> chris@westnet.com

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Received on Thu Feb 9 21:29:27 2012