No sound on Joust makes me sad...

boogiemanspud

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It's me again with Joust problems. I am running off of a switching PS if it makes a difference.

I replaced RAM 38 this morning since they came in the mail. (only replaced the one - does that matter if different brands?) Started the game up and I HAD JOUST!!! It played awesome (after cleaning P2 flap), had sound and everything. After about 4 games I shut it off and went to town. I came back about 6 hours later, turned it on, and no sound. I can get the "awful" sound when I push the test button on the sound board.

I read this post: http://forums.arcade-museum.com/showthread.php?t=80340&highlight=joust+sound and tried what it said.

I actually reflowed all headers on the sound board, reflowed headers on the ROM board. Tried wiggling the wires in the connectors, cleaned contacts with contact cleaner spray.

I tried re-seating the chip on the sound board. Tried what the above post said (grounding the molex on the sound board to simulate the board sending the sound signal. Nothing.

Anyway, is it common for the sound board to just "die" after a few plays?


That awful repetitive noise indicates that your sound amp and microprocessor are working on your sound board... so that is a good thing believe it or not.

Its quite possible your sound board is not able to process the instructions given to it by the CPU board. This could be a couple of things...

1. Check your connection from the ROM board to the sound board. There is a small molex cable connecting the two. Unplug it and re seat it... see if that helps.

2. Your PIA could be dead. This is fairly common. The PIA is responsible for taking the sound instructions from the CPU/ROM board and making them known to the sound board microprocessor so it knows what sound to play. Its one of the 40pin ICs on your sound board. Its a Motorolla 6821. You can test to see if the PIA is working by shorting any one of the sound select lines on the sound board (the molex header that the ROM board connection is hooked to) to ground. This simulates a CPU sound instruction. If nothing comes out... chances are its your 6821. If you hear something you recognize... then the problem lies within your ROM/CPU subsystem.

So does this sound right? I don't really know what to test on here other than what it said above.
 
If it plays when pressing the test switch (you will need to power down to shut it up afterwards) but it doesn't do anything when you ground one of the input pins from the ROM board, then it probably is the PIA (the big 40 pin chip next to the CPU). If you aren't lucky, it is still soldered directly onto the board. In the picture below, it is the chip with the serial number sticker on it.


D8224_jumpers_thumb.jpg


They are not hard to remove and put a socket down, but some of the traces are pretty fragile, so if you are not pretty handy with a soldering iron it can be a pain to pull them.

ken

Edit: It is not common for them to "die". But they are almost 30 years old and chips can fail especially if it hasn't been used in a while. It is possible that the embedded power supply failed and took the PIA (stands for Peripheral Interface Adapter, but really does mean Pain In the A**).
 
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They are not hard to remove and put a socket down, but some of the traces are pretty fragile, so if you are not pretty handy with a soldering iron it can be a pain to pull them.

So true... If you must replace the PIA and since the 6821 is a fairly cheap part, I would recommend you cut out your old one (from the top) with a good pair of micro cutters, ones that will suit the job. Then use a good iron, add a little bit of solder or flux to each pin on the top side and gently lift the pins out from the top. Then use solder wick or a solder sucker to clean out the feed throughs.
 
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O.K. thanks for confirming. My power supply (original) is still not working, I suppose it could have taken this out when it was malfunctioning. Good ol' 'lectronics and all! :)

I sent you a PM about this Yellowdog.

Thanks!

Edit: Thats a good idea about cutting the pins. That would be much easier! Thanks for the tips to a noob circuitry solderer!
 
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