G05-802 Glitchy/jumpy graphics

Looks like a PCB issue to me. X DAC maybe, or something associated.
 
I've run into this twice now on the black and white vectors and this will surprise you it is the potentiometers on the deflection board. You can just order potentiometer from digikey. You'll need the following:

500 ohm
100k ohm
4x 1k ohm

I'll double check sure all those values are correct.

Thanks
Gramt
 
Yeah, it doesn't look like the whole screen is jumping... just certain graphics. (unless Youtube is doing something strange to the video)

I watched it again, and it looks like the x axis is jumping really fast, so I still think it could be a potentiometer issue.
 
It's weird...

I should have made another video. I turned it on last night with the test pattern and the middle was all (for lack of a better word) squiggly, then it slowly got better until the grid was stable.

I think you might be onto something with the pots or possibly the big blue. It's a weird issue.

Maybe I'll post another vid later when I get home.
 
I should have made another video. I turned it on last night with the test pattern and the middle was all (for lack of a better word) squiggly, then it slowly got better until the grid was stable.

I think you might be onto something with the pots or possibly the big blue. It's a weird issue.

Maybe I'll post another vid later when I get home.

As a general rule of thumb, replacing the big blue is always a good idea, I know my Tempest was having issues with the spot killer coming on and it turned out to be the big blue!
 
As a general rule of thumb, replacing the big blue is always a good idea, I know my Tempest was having issues with the spot killer coming on and it turned out to be the big blue!

Power supply cap issues can cause the game PCB to output strange signals, but it won't cause a monitor problem. The power to run the monitor is AC from secondary windings in the power brick, and it's rectified to DC in the monitor… No big blue involved.

What's interesting about your video is that the P1/P2 scores are rock solid, while everything else on the display jumps around on the X axis. So I suspect this is more likely to be a PCB problem than a monitor problem. If you have a spare board or monitor, swap them around and see if the problem follows.

It can't hurt to replace the pots. You should do the ones on the game PCB as well if you're going that route. Bob Roberts sells kits for this stuff, and has exact replacements for the PCB pots.
 
Went back... still glitchy!

I took another video. I haven't done anything to the machine except for order some pots and a big blue (I have it in my head that I should do it!).

I bought this board from a KLOV member who assured me it was working and this monitor was not, so I'm still on the side of the monitor not working.

I do have an AD board that I can test in here to check the monitor status. Maybe I should do that. Either way, here's another vid for your viewing pleasure.

THis one is a little more rough I think.

I'm still convinced it's the monitor, and not the gameboard, but we'll see!

Sorry, didn't realize it was sideways till after I posted it.
http://www.youtube.com/watch?v=7U4LNyF5XTM
 
I still say it looks like a PCB issue to me.

Hooking it up to another (known good) monitor, or scope in X/Y mode, will tell you for certain.

BTW, it's fairly easy to determine if a large blue filter capacitor is good or not. Check the AC voltage your +5V line. If it's more than 20 or 30 mV, begin to suspect the cap. If not, it's fine.
 
I took another video. I haven't done anything to the machine except for order some pots and a big blue (I have it in my head that I should do it!).

I bought this board from a KLOV member who assured me it was working and this monitor was not, so I'm still on the side of the monitor not working.

I do have an AD board that I can test in here to check the monitor status. Maybe I should do that. Either way, here's another vid for your viewing pleasure.

THis one is a little more rough I think.

I'm still convinced it's the monitor, and not the gameboard, but we'll see!

Sorry, didn't realize it was sideways till after I posted it.
http://www.youtube.com/watch?v=7U4LNyF5XTM

Definitely swap boards. Or hook the monitor up to a different cabinet. My money is on it being a board problem.
 
Yeah, my bet is a 74LS194 shift register is acting wonky. I had a similar problem with a Battlezone PCB last year.

Notice the score and a few other things not jumping... if it was a pot the whole screen would jump at the same time.

Good luck with the fix.
 
Update!

Ok, so this is what I've done for swap testing...

I took an Asteroids Deluxe board from another machine and put it in. Initially, there was a weird graphics thing, then the pic was stable. Coudln't coin up a game because it's AD and the harness is different, but the pic was stable. Then I put my board back in and the pic was stable again! later I tried again and I still had the shakes though.

So then I took my board over to his house and put it into the AD cocktail. STABLE! WOO! Eventually the pic bloomed (his cab has its own issues) but it wasn't glitchy. I have a new big blue to install as well as some pots for the monitor. I'll do them one at a time instead of at the same time so if one fixes it we'll know.

WOO~
 
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