Star Trek Bally 1979 Chip Repair CPU Board

DreamTR

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Hi everyone, I was informed that my Bally 1979 Star Trek needs two chips on the CPU board replaced, but they are the long ROM chips and not the EPROM chips. One of them reads 620-29-7945

Anyone have an idea where I can get these replaced ?
 

+1!

Ed is awesome! Just placed an order myself last week and have always been satisfied over the years.

If you're talking about the 40 pin chips other than the CPU (motorola 6800) they're not ROMs... they're 6820 or 6821 PIAs (peripheral interface adapters). Ed (great plains) will have them. You should take a look at the sockets while you're at it.
 
Did you call him? His online inventory isn't always up to date.

As of Sunday, I'm out of these...

There is still one company that makes these, Wester Design Center, but they are real pricey. It may be a few years before the prices on remaining 6821's get high enough to make the WDC parts competitive.

The lower priced 6821's and the 68B21's dried up quickly after SG Thomson discontinued them a few years back. But, I did manage to get me a few nice, Chinese counterfeits. I can guarantee that they will fit into the 40 pin socket... but that's all I can guarantee.

When buying these - look at them carefully. If they all have the same date codes on them yet have different tooling marks (little dots on case) or different keying or different manufacturing locations (marked on bottom) - then avoid them!

Same applies to CPU's and many other parts of that era. The Chinese are hitting power transistors real hard now - watch out for them as well.

Ed
GPE
 
Hey Ed,

Is it time to start stocking up on pulls from Jameco?

Actually, I think the stocking up time came and went...
New ones used to be $2.10 each, Jameco's used ones are $3something.
Still, $4 isn't too bad considering there aren't many sources for these left.
I keep searching for NOS parts (I hate dealing with used parts) - sometimes I get lucky but it's getting harder and harder to find them.

Ed
 
Lindsey, If I get two of that same chip, it will replace the two on the CPU board fine? I think there's 3 on the board, but I am not sure if all 3 need to be replaced or not, I was told only the first two of the larger ones and not the EPROMS.
 
Lindsey, If I get two of that same chip, it will replace the two on the CPU board fine? I think there's 3 on the board, but I am not sure if all 3 need to be replaced or not, I was told only the first two of the larger ones and not the EPROMS.

There are 3 40 pin chips on the board but only 2 are PIAs (6820 or 6821). The "first 2" would really depend on how you're looking at the board.

The PIAs are U10 and U11 with the processor being U9. Those letters/numbers should be screened on the board near the chips. If you need to replace U10 and U11 you'll want either 6820 or 6821 PIAs.

Too bad I didn't realize before I shipped the Splatterhouse board... I could have thrown a couple in the box.

Let me know if you would like further clarification on any of this.
 
I am looking from top to bottom and the third chip being all the way at the bottom needing NOT to be replaced is what I am thinking..
 
I am looking from top to bottom and the third chip being all the way at the bottom needing NOT to be replaced is what I am thinking..

If that's the case and the board is oriented the way it would be when installed in the machine the top 40 pin chip is the processor (motorola 6800) and the second one down is a PIA (6820 or 6821).
 
I just bought a 5 chip set of new NOS chips for my Vector MPU from this Dave dude. Came with 2 6821's, 1 6800, the one smallest chip and the 5101? Anywho they were $24 shipped and here is his e-mail.

[email protected]
 
Lindsey, I checked the Star Trek today, and U10 and U11 are the middle and bottom chips. Where can I get U9 to be safe?
 
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