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

HI Jeff,

My therory is that the beam is centered a lot more during the game than the high score table (But turned off of course).

If the tube is worn/tired , you have to turn the brigness and contrast up to give a good image so the beam shows up faintly, just enough to give a glow in the middle. Its a bit like if you turn up the brigness on a standard CRT and see the retrace lines...

Thats my take on it anyway !!

Regards, Colin

  ----- Original Message -----
  From: Jeffrey Matthews
  To: vectorlist@vectorlist.org
  Sent: Saturday, February 11, 2012 6:53 AM
  Subject: Re: VECTOR: Asteroids G05-801. Perfect picture for 5 mins then a circle appears in the middle of the screen.

  Colin;
  I have an Asteroids that has the exact same issue.
  During the attract screen, I have a small white fuzzy dot in the ~center of the screen, (not as big as the one posted in this thread). It too goes away during the HS table!
  When I power down the game, I get a faint edge-to-center electron beam sweep then it slowly dies out, like the SK is not functioning 100%. It's not a super-bright beam that is going to immediately burn the phosphor but it is there none the less.
  I rebuilt the HV and Def but have not replaced the diodes as recommended by William B.
  I guess when I get the chance, I will.
  I thought I was going crazy that the "dot" was there during the attract and gone during the HS, I thought I was all alone............
  Jeff

  On 2/10/2012 7:27 AM, COLIN DAVIES wrote:
    I've had the Dot / glow in the middle problem myself, I tried a different deflection board and HV psu, but I think it was down to the CRT itself in the end being tired and having the brigness / contrast turned up. It was OK with another monitor. One thing I noticed is that the dot / glow in the middle in the middle dissapeared iirc during the High Score screen. I think I even tried another game board.

    Regards, Colin

    From: William Boucher <wboucher6@cogeco.ca>
    To: vectorlist@vectorlist.org
    Sent: Friday, 10 February 2012, 2:29
    Subject: Re: VECTOR: 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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> ** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org
> ** Please direct other questions, comments, or problems to chris@westnet.com

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Received on Sun Feb 12 09:15:47 2012