Ms. Pac-Man video output problem

grimholtz

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Hi,

Please see attached screenshots. Audio and gameplay are otherwise good. Video output is ... garbled. Anyone know which ICs or caps I should replace to fix this? I'd like to do-it-myself, not send to riptor or someone else... if possible.

Short of anyone knowing which ICs to replace, how can I start debugging this myself? I want to learn the trade and am quite good at electronics.

By the way, all lines are vertical. Any diagonal lines are due to me not holding the camera straight.

thanks,
grimholtz
 

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Looks like it is not Syncing up to me.....Probably a bad Sync Pot........
 
1) Adjust your horizontal hold/freq pot.

2) If that doesn't work, identify your monitor chassis model, and inform us of how the sync wires are connected...
 
thanks!

Thanks for all the help! I opened to machine and adjusted the pot with the machine turned on. It worked great; hardly had to turn it. Then I powered down and sealed up the machine. When I powered back on, the problem was back.

What the???

Scucci... where are the daughter cards? Are they part of the monitor?
 
pot

i am not sure what pot you tried but did you try the inductor inside the metal square cannister on the vert.horz daughter board? Tweak that a little.
 
You need to rebuild the monitor. Those pots are no longer available
The pot I adjusted is on the PCB, not the monitor. Can't I replace the pot (even if it's not the original part, but a substitute with the same resistance range)? I don't understand why I'd need to rebuild/replace the monitor.

i am not sure what pot you tried but did you try the inductor inside the metal square cannister on the vert.horz daughter board? Tweak that a little.
I'm attaching a photo of a PCB (not mine) where I've circled in red the pot I tried. Where is the inductor inside the metal square cannister--can you specify, say, 1 o'clock, 5 o'clock, 9 o'clock, etc...?

L351 is also no longer available
So how do people repair these boards when components break? Are they just thrown away? What about guys on the web who claim they'll repair your board?

thanks,
grimholtz
 

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you have to buy a cap kit and replace the old caps on the monitor chasis buy desoldering the old ones and soldering on the new ones
 
The pot you have circled on the board is the volume pot, and they are available.

Your problem is with the monitor, specifically the chassis.
 
Here are some photos:
http://picasaweb.google.com/grimholtz/Misc?authkey=Gv1sRgCOKtpear5Zr_uwE#
I'm not really sure what you want to see, so let me know if this doesn't cover it and I'll take more. I tried to take pics of the caps.

While doing this, I noticed the pots you guys have been talking about. There are 5 of them; 3 on one side and 2 on the other. I didn't see any labels, although it's possible I missed them. Which one is the horizontal sync?

thanks!
grimholtz
 
Here are some photos:
http://picasaweb.google.com/grimholtz/Misc?authkey=Gv1sRgCOKtpear5Zr_uwE#
I'm not really sure what you want to see, so let me know if this doesn't cover it and I'll take more. I tried to take pics of the caps.

While doing this, I noticed the pots you guys have been talking about. There are 5 of them; 3 on one side and 2 on the other. I didn't see any labels, although it's possible I missed them. Which one is the horizontal sync?

thanks!
grimholtz

the monitor is a GO7 CBO 19 inch probably needs a new flyback and a full cap kit, you can get one from bob roberts http://www.therealbobroberts.net/g07deluxe.jpg hope your handy with a soldering iron
 
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