Centipede AR2 voltage

[Bax]

Hey all. Working on a centipede and did the partial cap kit on my ar2 board. Not sure why it didn't cover all the caps but here's what's going on. Got the 5v dialed into 5.05v reading from the cpu board. The +22 is at 23.85 and -22v is 24.08. With the 22v being off on both, what damage could it be doing to the board? What needs to be corrected on the ar2 board? I know I've got to replace ram and the j1 rom for starters but don't want to leave game on if the 22v will damage anything

 

[andrewb]

1) You never need to replace caps on an AR. They are always still good, as Atari used very good ones, they're overspeced, they don't get hot, and they're low voltage. Save your money. However, the thing you absolutely want to do on all AR's is replace the 2N3055 bottlecap transistor, as this is the part that does the heavy lifting, and it can send 12V straight to your game board if it fails. So you always want to replace an original one with a quality replacement. Only replace it with one from a known, trusted source, as there are a lot of fakes out there. Do not get one from ebay, aliexpress, or any other gray market seller.

2) The +/-22 are normally high, and +24V/-24V give or take a volt is normal.

 

[Bax]

funny you say to change the bottlecap. the guy I got the cap kit for said the opposite lol. I'm glad that my voltages are good and can move on to fixing the board now. bummer I spent the money when I probably didn't need to.

 

[andrewb]

Who gave you that advice?

If you want to read about it, search here for posts by me, with 2N3055 in the body. You'll find hundreds of posts about it.

 

[nulogix]

I second 2n3055. Also, second the reputable source like mouser or digikey. I had 4/4 2n3055 die in a span of 2 or 3 months. Likely all counterfeit.

 

[Bax]

the guy I bought the cap kit from said that they rarely go bad. I've read that they do so that is why I questioned him.

 

[andrewb]

the guy I bought the cap kit from said that they rarely go bad. I've read that they do so that is why I questioned him.

Who was it? I'm not aware of anyone who sells kits, who would give that advice, so I'm curious.

Feel free to PM me, if you don't want to say it publicly.

 

[Bax]

My mistake it was the LM305 that he said typically doesn't go bad. the 2n3055 did come with the kit. my mistake. was thinking wrong part.

 

[andrewb]

Ok, that makes more sense.