Joust help

mcjeremy42

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Donor 2012
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Hi, people!

So I bought a Joust a while back and knew it was a project. Here's what you should know:
1) all ram has been replaced in the past year
2) found a silicon resistor knocked off the power board and repaired it. Gave me back coin and button lights
3) i have a 1-3-1 error that's been killing me!
4) turned on to a yellow screen, no rug.
5) I've replaced the 40 pin ribbon cable, but not the smaller one.
6) batteries are new, and still AA's. The holder looks to have had a rough repair at some point.

Here's what I did yesterday:
1) read a lot in these forums. Thanks to old posts, I decided to remove all socketed chips and clean them. I used a tiny bit of electrowash in the sockets, and made sure all pins were good.
2) rehooked it up and crossed my fingers....holy $h!t! I've got a rug pattern!! Booted up to a screen (sorry, no pics....wasn't expecting it to work!) that gave me a ram or rom error 34. The screen had white vertical lines through it.
3) cycled through a menu real quick, and got the high scores screen. Looked good except for the white lines.
4) put a credit on and pressed 1 up start. Game screen! But blocky pixels...then before anything could really happen, reset.
5) removed ribbon cables and sprayed electrowash on the pins, wondering if they could be dirty. Replaced and now I'm back to a 1-3-1 error and this time a red blank screen with no rug pattern.

I'm a noob when it come to electronics...I can solder, and replace a part one for one, but may need help metering. I know I should check power on the ram legs, but where do I put the other test lead? Is the a specific ground? And I'm guessing I'm checking DC power, but want to check before I potentially blow anything and make it worse.

ANY thoughts or ideas would be much appreciated! I'm wondering if it's the socket for the 3-1 ram? Anyone know where to order them from and have a part #?

Sorry if this is a rehash of earlier posts, but wanted to give my circumstances, in case specifics were needed.

Thanks! --jeremy

PS--thanks Pete in Mass (Local413) for giving me the idea of the socket in the first place!
 
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I'd say with maybe... 90% certainty that your problem is your power is low. I just fixed a Stargate yesterday, same thing, giving ram errors, weird rug patterns, etc.... tested the voltage, the 5 volts was sitting at about 4.3.

On these machines you've got several points where the power can be an issue, you need good voltages out of the power supply (of course)... and then you also need a good molex connector at the main pcb's power input (it's from the factory usually an insulation displacement connector, these suck)... and then you also need good solder joints on the main pcb so that the power gets through the pins onto the board.

Once you get a good 4.9-5.1volts D.C. onto that main board, she'll boot right up for you.

To check it, put your meter on DC. Put the ground lead on the ground trace running around the board (where the screws are). Then carefully, VERY FUCKING CAREFULLY touch the red lead to each of the 4 corners of the ram chip (any of them). One of the corners will be a ground (and you'll get a 0 reading)... one will be your 5volts, one will be your -5volts, and one will be your 12volts. Neat, huh? The only one that's super important to be exact is the 5volt. It needs to be at least 4.9, and no more than 5.1.

Reply back and let us know what you've got.
 
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