Help! Robotron

Evil Reny

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Donor 2011, 2013
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Jun 9, 2009
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Calgary, ALBERTA, Canada
Hi all I have a Robotron machine that worked great up untill recently, when you switch it on the screen is all red with lines.
The game seems to still play fine but you can't see what your doing.
Any help would be great
Thanks
 
Try pulling and reseating the video cable on both ends.

Also try to go into test mode (push test button down and press reset on the bank of switches inside the coin door). Keep pressing advance until the color bars come up and take a picture if possible and post it. That would help a lot.

ken
 
is there a switching power supply in the cabinet? Check the voltage and adjust if needed.

after having a switcher in this game for a while, I can't recommend it. Too tempermental and it erases high scores. rebuild the original or buy one that's been repaired by someone who knows what they are doing.
 
Re:

I'm not an expert but I think it might be a PCB problem...Does the sound and everything work?
 
I do have some flow charts here that are a lifesaver (IME) when working with Williams boards. I'd post a link but last time I posted a link to an image of a flowchart, I have Fromm send me a nice message. Actually, I'll just link to the site where I got them... I should be safe with that.

You'll need a DMM and a logic probe (I got mine for 5 bucks off ebay)... but well worth having IMO.

Should be able to hunt down SOMETHING with them I'd hope.

http://vidpin.com/tech_videorecap.asp
 
I'm gonna take a wild stab, but all Williams game of the vintage (Robo/Joust/Stargate)
have video decoder chips on the main board.

It "looks" like that could be the problem.

(...then again, it looks like a loose connector problem too ! )

If you have any other Williams board, try swapping the decoders
( They should be labeled Video Decoder #4 and #6. They are socketted
near the center of the main PCB )

Good Luck.

Cheers,
Steph
 
+5=+5.5
+12=+13.1
-5=-5.4

Is this o.k or should I adjust?
Sorry I'm super new at this so any help would be great
Thanks

Pic looks like a RAM problem. What codes is coming up on the ROM board LED when the machine is booted up?

The +5.5 could be a problem and should be adjusted down to no more than +5.1 if you have a switcher in there. If you have the orignal linear ps the adjustment is different.
 
Re:

Have you tried at least reseating the roms and maybe the edge connector(s)? Doesn't always solve the problem but it's pretty much the first step I always take.
 
Sorry it took so long. Any help?

At a minimum you have a burnt shift register in the I row. You can confirm this by raising pin 23 of the right decoder chip high. Search for discussions on this topic.

I have a working MPU I will trade for your broken MPU + $$ if you are not up to this repair.

Saltbreez
 
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