Joust issue(s)

mochaman

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Picked up a non-working Joust. Trying to debug this. I was getting a 1-3-1 error at first. Then the next morning, I was getting a "u"(?) on the display. I checked voltages at ps and good. But, I checked them at the board connectors and it got weaker as I went from board to board. By the time it gets to main board, it was down to 4.4-4.6vdc. I've wiggled/pushed connectors/ribbon cables and doesn't change. What would be the next step?
 
upgrade the ram. replace the ribbon connections. replace the power input headers and connectors then go from there.
 
Was able to get back to 1-3-1/1-3-2 error code. Reseated chips. While doing that I noticed that the decoder chips were reversed, i.e.: 3G was in 3C spot, vice-versa. Would this cause problems with these chips?
 
Was able to get back to 1-3-1/1-3-2 error code. Reseated chips. While doing that I noticed that the decoder chips were reversed, i.e.: 3G was in 3C spot, vice-versa. Would this cause problems with these chips?

Doubtful. I'm pretty sure they are the same type of chip, just different code on them. I dont have a board in front of me to confirm though.
 
you're getting ram errors because the voltage is probably too low. in my travels I've found Joust for whatever reason to be the most prone to issues stemming from low voltage, despite the fact it's otherwise identical to Robotron (which cooperates well) and Sinistar (which can be a pain in the arse)

there's 4 capacitors nearest the power header on the MPU. each carries a voltage: +5, +12, -5 .. the final axial cap is for ground. the first 3 should be 100 uf / 16V stock, and the axial 22 uf / 16V. you can just read them too. :) these caps are ancient now and you will lose power through them. the rom board should have 2 of the 100 uf / 16V caps on it as well -- I personally replace these with 100 uf / 25V.

replacing the headers is also particularly important, because the factory ones weren't that great to begin with.

if you know how to crimp molex, I also encourage replacing the plug to the MPU. if you're using a linear power supply (I imagine you are) you should also change the plug(s) to the outgoing DC header.

if you don't feel confident you can resurrect this, I now am offering repair services which cover MPU, rom, and power supply boards. if you want extra diagnostic on the input board to make sure the ribbon is good, I can check that as well.
 
Swapped decoders will definitely cause a 1-3-1. Get the voltage up with the suggestions here; headers, connectors, power supply rebuild. Once it is working, you can try the 4164 DRAM upgrade.

Kirk S.
 
You should measure at the chips, not the power supply. 5.05 is perfect

I wanted to know at ps so I know that there is enough from the source. I know that I am under 5v at chips.
 
Swapped decoders will definitely cause a 1-3-1. Get the voltage up with the suggestions here; headers, connectors, power supply rebuild. Once it is working, you can try the 4164 DRAM upgrade.

Kirk S.

doh, missed this step. yes, wrong decoders means the data won't reach the ram. :)

I wanted to know at ps so I know that there is enough from the source. I know that I am under 5v at chips.

above 4.90 is very good. 4.85 and below becomes uncharted territory. game might run, but reset after awhile. or it throws a 1-3-1.

there's a picture in my PSU guide in the signature that shows where to measure at chips. be certain you use one of the chips nearest the headers, don't do it at the ram -- one slip and your ram is toast and other parts. I've also stressed that +5 is the only important one, if your power supply is outputting the other 2 good then don't worry about them.

also if you didn't know, the grey wires at the PS and MPU are +5, and black wires are ground. you can get an idea of how much juice you're losing between the power supply and MPU. if it's above a half volt, you'll have to throw the battery at it I listed in my last post.
 
Did a little more testing on voltages. Was hoping the ps was decent enough to use but unfortunately its not. Going to start at the beginning. Rebuild the ps, redo connectors. Will report back on progress.
 
Did a little more testing on voltages. Was hoping the ps was decent enough to use but unfortunately its not. Going to start at the beginning. Rebuild the ps, redo connectors. Will report back on progress.

if you need the cap kit and/or the rebuild kit i have the best quality in stock for all the williams p/s.
https://www.arcadepartsandrepair.co...-d-8784-mega-deluxe-power-supply-rebuild-kit/
https://www.arcadepartsandrepair.co...8784-5773-09679-00-power-supply-105c-cap-kit/

and kits for almost all power supplies
https://www.arcadepartsandrepair.com/product-category/rebuild-kits/power-supply-rebuild-cap-kit/
 
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