Asteroids, Circle and Dot in the middle of screen.

Arcadenut

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Ok, almost done with this Asteroids, one last issue with it.

As you can see in the picture below, there is a circle and a dot in the center of the screen. Other then that the picture is perfect.

Adjusting the Brightness and Contrast does not get rid of it. I can turn them all the way down (so you can't see anything else) and the circle and dot are still visible.

Any idea if this is a board problem or a monitor problem?


Any suggestions would be greatly appreciated!


AsteroidsCircleInMiddle.jpg
 
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Man, those are some crappy-ass scores.




Oh, and... Free bump. :D
 
At least I can get scores on mine :eek:

You fix yours yet? Or do you need to bring it here?

Oh! He called you out on the carpet! :D

By the way. That's not such a bad score. (As long as you close your eyes after you hit the start button). :D

Darren Harris
Staten Island, New York.
 
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Check your hv diode on the flyback. I had my Asteroids Deluxe making funny rings in the middle and was recommended to check the diode..finally. I pulled the diode and rust dust poured out. Hmmm, I wonder if that's the problem. Picked up some cheap springs from the hardware store, cut them to fit with a new diode and WOW, what a difference in the picture! And no more spot in the middle. Hope it helps.
 
At least I can get scores on mine :eek:

You fix yours yet? Or do you need to bring it here?

Ouch.

Nope. At the moment, it is under a pile of boxes from clearing all the stuff out of my new-roommate's room. I need to dig it out... :rolleyes:
 
Check your hv diode on the flyback. I had my Asteroids Deluxe making funny rings in the middle and was recommended to check the diode..finally. I pulled the diode and rust dust poured out. Hmmm, I wonder if that's the problem. Picked up some cheap springs from the hardware store, cut them to fit with a new diode and WOW, what a difference in the picture! And no more spot in the middle. Hope it helps.

Rings on a diode? Do you have a part # or a picture?
 
Ouch.

Nope. At the moment, it is under a pile of boxes from clearing all the stuff out of my new-roommate's room. I need to dig it out... :rolleyes:

Well, I might be getting a rebuild kit or two for the G05, so if you bring it by next week I can probably rebuild your monitor too. I'll let you know if I get the parts.
 
Well, I might be getting a rebuild kit or two for the G05, so if you bring it by next week I can probably rebuild your monitor too. I'll let you know if I get the parts.

I owe you many drin... Err, other favors. :D

Have I said how awesome you are, lately? I don't think I have.

129079115236105953.jpg
 
Ok, I capped the monitor and I replaced Q503 and Q506 (TIS98) in the Spot Killer section.

The Good News: It fixed it. Picture came up beautifully.

The Bad News: It only lasted about 5 minutes before it showed up again.


So it sounds like something is killing one of the Transistors or there is another fault within the Spot Killer circuit.

Or could it be a PCB issue?

** UPDATE**
After leaving it turned off for a bit, I turned it back on and the picture was perfect again. Then 5 mins later, the circle re-appeared.
 
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Ok....

Here is what has been replaced so far in the Spot Killer section:

Q503
Q506
R518
R528
R529
R523
R524

Replacing Q503 and Q506 improved the issue, but the issue still comes back. Initially the monitor would display the circle and dot at start up. Replacing Q503 and Q506 fixed that until the monitor has been on for about 5 minutes.

The odd thing is, is that the Spot Killer LED is Lit even though I have perfect deflection.

Anyone have any ideas why that might be? The LED is controlled by Q506 and it was replaced.

I'm thinking possibly in the Z Amplifier now.
 
I had one once with the spot killer always on....and a perfect picture. On mine Q506 was installed backwards.

Edward
 
I had one once with the spot killer always on....and a perfect picture. On mine Q506 was installed backwards.

Edward

I'll double check it, but I'm 99.99% sure it's installed the correct way. Maybe a defective part? I can try another one and see if it does the same.
 
Ok, dug around a bit more, and found something interesting...

I measured the voltage at R524 and found that the voltage is +26.4V to start with (when first powered on), and then it slowly rises to +27V. When it gets to about +27.5V the Circle and DOT appear on the screen.

There is one cap that I didn't replace since it's a 105F cap, but I may replace it with an standard cap to test. Not sure how critical the cap temp would be in a home environment and I would rather not order just a single cap...
 
More poking around....

Tested D509 and found that it was 86V and the manual says it should be 90V. Is this within tolerance or is this something I should look at further?

Any suggestions on what to look at?
 
Mine has the same issue. It doesn't bother me too much game play wise, but I do worry that it could be damaging something. Did you ever figure out what was causing this problem?
 
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