Sound problem with Atari 800

[Megamania]

When I was very close to finish restoring an old, bad condition Atari 800, I realized it has a weird problem: I get no sound, except for (apparently) the noise generator.

 

For example, when I turn it on I get the familiar noise of the computer looking for devices. When disks are loading, I can hear the "bleeps".

 

When I try a game, I only get *some* noises and no music. In Berzerk, for example, I can hear the synthesized voice and very few other noises; River Raid is completely silent except for a low-volume "mmmp" when I shoot a missle. Megamania is completely silent.

 

I know it's not the video cable or the TV because both are working fine with another Atari 800.

 

 

Any ideas about what I can do? I know I can break it if I just start try to fix it on my own, so please help me!

[R.Cade]

It could be capacitors are leaked and gone, but it could also be a POKEY chip has gone bad. Fortunately, they are very cheap and plentiful at the moment- I saw someone on here selling them for $0.80/each recently.

[+StaxX28]

maybe is the same problem I had last year... look here --> http://www.atariage....39#entry1525539

[atariksi]

maybe is the same problem I had last year... look here --> http://www.atariage....39#entry1525539

 

That thread talks about POKEY or LM358 opamp being issues related to audio but nothing about which capacitors are related to audio functionality. That would be good to know for repair work which capacitors relate to video and audio output since swapping chips are pretty easy to do if they are socketed.

[analmux]

OK, but also discussed was this:

 

Maybe the simplest could be, if you have pokey chips in sockets in both machines, then try exchanging them, and see if it will give correct sound again. If yes, then you know that it's only a faulty pokey chip.

[Megamania]

Maybe the simplest could be, if you have pokey chips in sockets in both machines, then try exchanging them, and see if it will give correct sound again. If yes, then you know that it's only a faulty pokey chip.

Thanks everybody for all the inputs. I will try exchanging the chips from one Atari 800 to the other, hoping they're not soldered.

 

Can you give me an idea of where Pokey is located? I searched google but I want to be sure I make no mistakes.

[atariksi]

Maybe the simplest could be, if you have pokey chips in sockets in both machines, then try exchanging them, and see if it will give correct sound again. If yes, then you know that it's only a faulty pokey chip.

Thanks everybody for all the inputs. I will try exchanging the chips from one Atari 800 to the other, hoping they're not soldered.

 

Can you give me an idea of where Pokey is located? I searched google but I want to be sure I make no mistakes.

 

It's socketed on all Atari 400s and 800s. It's on the main board (not on the cards). CO...294. Forget the exact number in between.

[analmux]

IIRC you can read "CO12294" on the pokey chip. I'm not sure whether it makes any difference if you have a 800 or 800xl.

[Megamania]

I swapped the Pokey chip from a working Atari 800, and I got sound again! I'll just need to put my hands on a Pokey now.

 

Thanks guys!

[atariksi]

I swapped the Pokey chip from a working Atari 800, and I got sound again! I'll just need to put my hands on a Pokey now.

 

Thanks guys!

 

There's one in Atari 5200 that's socketed while you look for one or if you have a broken 5200. I wouldn't bother with broken 65XEs/130XEs as they are soldered on those systems.

[Megamania]

There's one in Atari 5200 that's socketed while you look for one or if you have a broken 5200. I wouldn't bother with broken 65XEs/130XEs as they are soldered on those systems.

Is it a problem if it is soldered? Can I just desolder it, or is it going to be a problem (i.e. it won't fit unless it's perfectly clean)?

 

I'm asking because I was going to buy one of those pokey chips soldered on a game cartridge that are being sold here on the forums...

[mimo]

you can desolder it if you have the skill. They are also soldered into Atari 7800 Ballblazer carts, and available new from Bradley at Best Electronics for $10 (but his minimum order is $20 by credit card, $35 by Google checkout or $50 by payscam

 

or maybe put a wanted add in the marketplace forum

[atariksi]

There's one in Atari 5200 that's socketed while you look for one or if you have a broken 5200. I wouldn't bother with broken 65XEs/130XEs as they are soldered on those systems.

Is it a problem if it is soldered? Can I just desolder it, or is it going to be a problem (i.e. it won't fit unless it's perfectly clean)?

 

I'm asking because I was going to buy one of those pokey chips soldered on a game cartridge that are being sold here on the forums...

 

Sure, you can desolder it if you have desoldering machine gun. It's too messy for me.

[atariksi]

you can desolder it if you have the skill. They are also soldered into Atari 7800 Ballblazer carts, and available new from Bradley at Best Electronics for $10 (but his minimum order is $20 by credit card, $35 by Google checkout or $50 by payscam

 

or maybe put a wanted add in the marketplace forum

 

$35 minimum for Google-- does that mean their overhead for transactions is more than credit card?

 

$50 by payscam-- never heard of that one-- do any transactions come out that are not scams?