Re-capping an Atari 800 - which caps?

[StickJock]

My power supply seems to work fine, but I noticed that the big cap in the corner of the power supply board (C208, 4700uF) was bulging a bit on top, so I suppose that I ought to replace it.  What other caps should I replace while I am at it?  Any suggestions on where to pick up the right replacements, or suggestions on alternate capacitor specs if these are not readily available?

 

I noticed that these have plastic tops instead of the metal tops with the incised "X" on them.  I suppose that this is just a change in manufacturing in the past 40 years?

 

I also thought that it was odd that these two big caps have three solder points on the PCB instead of two....

 

Thanks.

[spspspsp]

Since they are all 40 years old, I'd just replace them all. There aren't too many, and you can probably use modern general purpose caps for everything. The 800 has some axial caps, though, which are not available from all suppliers. Be patient with the filter capacitors though. They have strong connections to ground.

 

My vote? A cap kit like this:

https://console5.com/store/atari-800-computer-cap-kit.html

 

Should have modern equivalents for the caps, and this kit includes axial caps.

[BillC]

32 minutes ago, spspspsp said:

Since they are all 40 years old, I'd just replace them all. There aren't too many, and you can probably use modern general purpose caps for everything. The 800 has some axial caps, though, which are not available from all suppliers. Be patient with the filter capacitors though. They have strong connections to ground.

 

My vote? A cap kit like this:

https://console5.com/store/atari-800-computer-cap-kit.html

 

Should have modern equivalents for the caps, and this kit includes axial caps.

The electroytic capacitors Atari used in on-board power supplies are, for the most part, RADIAL capacitors which is what the image appears to show. Axial capacitors have a lead on each end.

[spspspsp]

38 minutes ago, BillC said:

The electroytic capacitors Atari used in on-board power supplies are, for the most part, RADIAL capacitors which is what the image appears to show. Axial capacitors have a lead on each end.

Most are radial, but there are two (I think) axial caps on the 800 power board. I was suggesting that he consider replacing all of the caps if some are bulging, and the kit I linked includes axial caps (or did when I purchased it).

[cwilbar]

I too was going to put the link to console5.com on the kit, though I have not bought any of their kits yet, so I don't know what capacitors (brand, specs, etc) they include.

 

If you want to buy your own (to spec out best rated caps/etc) from the DigiKey, Mouser, etc, then console5 lists the caps on this page:

 

https://console5.com/wiki/Atari_800

 

 

[Sugarland]

I had very good results from the console5 kit. Quality caps as far as I could tell. Still have one kit to install.

[Osgeld]

console 5 kits seem expensive until you spend hours on digikey or mouser doing a deep dive into million o parts 

 

if you do not use digikey, mouser, or similar just spend a few extra bucks and get a kit, even the worst one on the market from no name china listing on ebay will be as good if not better than the originals cause ... time and advancement 

 

just for reference those plastic top caps are not bad they dome totally brand new from the factory, cause the plastic is domed, and they blow out their arse, not their tops

Edited September 4, 2020 by Osgeld

[StickJock]

2 hours ago, Osgeld said:

just for reference those plastic top caps are not bad they dome totally brand new from the factory, cause the plastic is domed, and they blow out their arse, not their tops

So maybe the caps don't need replacing?  Only the cap in the corner has the top domed.  The one in front of it, with the label on it in the pic, has a flat top.  These are the same cap, so it seems odd to me that one is domed and one is flat.

[TGB1718]

3 hours ago, StickJock said:

So maybe the caps don't need replacing?

For peace of mind I would do it anyway, "just in case", did my 1050's some years ago, well worth the effort

[starfighter]

I have in the past successfully replaced PSU capacitors in other retro computers and completely replaced the external Atari 8-Bit PSUs by modern equivalents. So while replacing PSU capacitors (or the complete PSU for that matter) might always be a good idea in general, I would be reluctant to replace other capacitors in a perfectly working Atari 8-Bit computer. There is always a risk that afterwards things might be worse than before. I understand that Atari used very high quality capacitors back then and a very experienced Atari repairman told me not long ago that he would yet have to see an Atari 8-Bit computer that failed due to an aging capacitor. Of course, it might happen eventually, but before that, probably other components, like RAM chips, etc are more likely to fail.

[gilsaluki]

I have never looked at my 800s caps.  What made you look at yours?  Routine.  Something I need to do every few years or so?

[StickJock]

1 hour ago, gilsaluki said:

I have never looked at my 800s caps.  What made you look at yours?  Routine.  Something I need to do every few years or so?

I've got the machine apart for an Incognito install, and I happened to notice that the big cap in the corner has a domed top and it's neighbor doesn't.

 

A while back, I had to replace several caps on a TiVo Series 3.  I think they were on the power supply board as well.  They were clearly bulging (and had the metal top with the '+').  It stopped booting up with the larger after-market hard drive upgrade, but would still boot when I put the original hard drive back in.  It had also developed some issue with non-HDMI video output.  Replacing the caps (3 or 4 of them - I tacked them onto a coworker's DigiKey order) fixed all of that.  This was in the time frame where there was a batch of "bad caps" out there and things were failing left & right.

 

[mimo]

7 minutes ago, StickJock said:

I've got the machine apart for an Incognito install, and I happened to notice that the big cap in the corner has a domed top and it's neighbor doesn't.

 

A while back, I had to replace several caps on a TiVo Series 3.  I think they were on the power supply board as well.  They were clearly bulging (and had the metal top with the '+').  It stopped booting up with the larger after-market hard drive upgrade, but would still boot when I put the original hard drive back in.  It had also developed some issue with non-HDMI video output.  Replacing the caps (3 or 4 of them - I tacked them onto a coworker's DigiKey order) fixed all of that.  This was in the time frame where there was a batch of "bad caps" out there and things were failing left & right.

 

Modern caps don't seem to be up to the job, everything is built down to a price.

The original xbox's all need new caps both of mine died within days of each other.

I have probably had 50 or more 8 bit ataris pass through my hands and none of them have ever needed caps.

C64s BBC micros etc regularly emit the magic smoke though