Asterioids G05-802 weirdness

MitchO

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So this is my first machine with a vector monitor (Asterioids w/ Electrohome G05-802 monitor) and naturally it has decide to act up. Hopefully the pictures kind of show what it is doing. The issues seems to happen somewhat randomly though it tends to be worse if there are a lot of things on the screen. If you can't tell the objects in the upper right hand side of the screen want to flatten out into a horizontal line. When it gets real bad the objects in the upper left and lower right will also display the same behavior.

Is this a case of it just needing a cap kit or is something else needed?

Thanks,
Mitch
 

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On the test screen, the diagonal line that should be going into the upper right corner is messed up. But only the very upper part of it.
It looks something like this.
Code:
----
   /|
 /  |

and then changes to this very rapidly back and forth.

Code:
----
 ---|
 /  |

This is just the box in the upper right hand corner.

I don't know if that ascii art helped or not. I guess I can try and take a picture.

None of the symptoms on that page seems to be an accurate match from what I can tell.

Mitch
 
If it only happens on the very top or very bottom, then I'd check the vertical deflection transistors mounted on the frame.

In fact, if they've never been done, I'd replace all 6, and reflow the pins where the connectors from them plug into the deflection chassis. Just to see if it helps...
 
I forgot to mention on the test screen that the left number one in the middle of the screen wants to bend to the left a bit as well.

Mitch
 
Definitely replace all your deflection transistors, reflow the connectors, and maybe cap it, too. Make sure the monitor isn't the problem. Got an O-scope? Hook up the X/Y outputs to it to verify the board is good or not...
 
I see that Bob Roberts has a cap + xsistors kit for the G05-802. Would his xsistors be the transistors you are refering to?

I do not have an o-scope unfortunately. The closest thing that I have is a Vectrex and I don't really think I want to go there. :D

Mitch
 
Yes, that kit should come with 4 or 6 transistors. I can't remember how many the 802 had...
 
OK, I guess I'll pick that kit up and see how it goes. :)

Are there any hidden gotchas on the G05-802 monitors? Like extra stuff you need to discharge or parts that blow up when you do a cap kit?

Thanks,
Mitch
 
Hmm, I don't have a spare board to test with. Is there any troubleshooting I should try besides the usual reseat the chips procedure?

Mitch
 
Here's a couple more pics. You can kind of see where the diagonal line in the upper right hand corner is blurred. Also, it is the lower part of the left number one in the middle of the screen that wants to go left, not the top part of it as I stated earlier. You can see it if you look closely.

One other thing I noticed. When I turn the Asteroids on to the test screen cold, the outer test box is larger than the screen. I can barely make out the top and bottom but the sides of the box are completely off the screen. It kind of jitters a bit and then after a minute or so it goes down to it's normal size.

Any thoughts?

Thanks,
Mitch
 

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I see that there is a cap kit available for the Asteroids system board. Is this worth doing and any chance it could be part of my issue?

Thanks,
Mitch
 
I see that there is a cap kit available for the Asteroids system board. Is this worth doing and any chance it could be part of my issue?

Thanks,
Mitch

From my reading and experience, the PCB Problems are often just dirty sockets or ICs and broken pins.

(This needs to be done to rule it out)

You need a good magnifier and light, and a lot of patience. Maybe a bit of scotchbrite or scourer for scrubbing the dishes. Don't use steel wool.

I Get an IC Puller and remove each socketed IC one at a time and clean the pins. (Go with the grain so to speak) Place the ic on a flat surface so YOU dont break pins. If you aren't confident don't do it.

If you do, make sure the IC Goes back in the same way it came out (There is a dot in the corner of each IC, All the dots need to face the same way as each other.

Sometimes the tiny legs break off, and then that leg needs to be re-soldered or the IC replaced. The larger IC's have burnt data on them, so can't easily be purchased without more further effort.

I have an electronic background, and I found this challenging, so take your time and get it right if doing it.

Ask questions anytime . .

Even after doing this, the socket still may be the cause, so if the exact problem occurs, some sockets may be needed too (Expert experience level needed)

Good luck
 
Last edited:
Thanks, as it happens only the ROM chips and CPU are socketed. I have cleaned them and didn't see any changes. I also inspected the board for bad solder joints and didn't notice any.
I noticed a vaguely similar issue to mine on the website that modessitt linked to that mentioned replacing the board caps fixed the issue. That's why I asked about it. I suppose it can't hurt to recap it anyway.

But keep the ideas coming. :)

Thanks,
Mitch
 
Well, just did the game board cap kit and no change. I guess I'll try the monitor cap kit next just to rule it out. Unless someone has an idea of something else to check on the board.

Mitch
 
It looks like crappy solder joints on the headers for the monitor deflection board. That monitor is notorious for cold solder joints at the headers.

Pull the deflection board out of the monitor and reflow all of the solder on all of the headers and test it again.
 
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