Atari XL Power Supply Issues

[Pilsner73]

I have two Atari 800xl rebuildable power supplies in need of help. One is the long black brick, the other is the white and brown brick. http://www.myatari.com/ebay/psxl.jpg the two to the left side of the picture.

 

The black brick is putting out according to my multimeter 11 instead of 5. What are the possible causes/remedies? I'm a novice but am not afraid to learn btw.

 

The white/brown is putting out 5.32, seems a bit high is there something I should check/replace also?

 

Thanks!

[zylon]

I have two Atari 800xl rebuildable power supplies in need of help. One is the long black brick, the other is the white and brown brick. http://www.myatari.com/ebay/psxl.jpg the two to the left side of the picture.

 

The black brick is putting out according to my multimeter 11 instead of 5. What are the possible causes/remedies? I'm a novice but am not afraid to learn btw.

 

The white/brown is putting out 5.32, seems a bit high is there something I should check/replace also?

 

Thanks!

 

http://www.atariage.com/forums/topic/178058-testing-atari-xlxe-power-supplies/

I'll remind you of our discussing this before. You have to test them under load or the readings will always be too high. If the DC voltage runs high, it's because the voltage regulator inside the box is bad or failing.

[Pilsner73]

I have two Atari 800xl rebuildable power supplies in need of help. One is the long black brick, the other is the white and brown brick. http://www.myatari.com/ebay/psxl.jpg the two to the left side of the picture.

 

The black brick is putting out according to my multimeter 11 instead of 5. What are the possible causes/remedies? I'm a novice but am not afraid to learn btw.

 

The white/brown is putting out 5.32, seems a bit high is there something I should check/replace also?

 

Thanks!

 

http://www.atariage.com/forums/topic/178058-testing-atari-xlxe-power-supplies/

I'll remind you of our discussing this before. You have to test them under load or the readings will always be too high. If the DC voltage runs high, it's because the voltage regulator inside the box is bad or failing.

 

I know the one is outputting way high, and the other one seems a tad high. The really bad one the computer won't even turn on correctly because of that, just wondering what parts I need to check/replace and where to get them. The 5 volt lines are reading 11volts which is not good.

Edited May 11, 2011 by Pilsner73

[zylon]

Hmm. Most likely the regulator inside the power supply is failing so you'd have to open it and replace it. I've never cracked one of those open so I don't know what you will find in there. I'm going to guess it has a 7805 regulator inside since Atari was very fond of those.

[Pilsner73]

I am checking with Best electronics to see what part he thinks it is. I see a 7805 at Radio Shack but it say's 1amps and I believe this Atari power supply ran +5v and 1.5a so want to get the correct part.

[zylon]

All mine are either the ingot type or the smaller ones that came with XEs. If I had the serviceable type, I'd open it to check for you.

[Pilsner73]

Ok I think the 7805 I need is called an l78s05cv regulator. Now Looking at the power supply I noticed some black marks around the 4700uf 16v capacitior and some of the resistors in it look burnt a bit. Now some questions on where and what parts to purchase

 

The l68s05cv is easy enough to find and get the three pin/leg model.

Now for the 4700uf16v do I want to get the long pins sticking out that can be trimmed or the snap in model?

 

The resistors, I can't really tell what color they are because of the burning but R3 and R4 need replaced. According to a document I read they are 5.1 - .01% 1/2w and 8.2 - .01% 1/2w. Now is the 8.2 and 5.1 ohms or kohms? Also does the percent matter?

 

Thanks!

[zylon]

I buy a lot of components from Jameco and even Best Electronics depending on price and quantity. I've gotten ahold of a brown/white rebuildable today. It's working fine so I'll open it and see what's inside.

 

Update: Have opened the box and pic'd some of the components. Mine doesn't have a R3 or R4. You might be able to see the colors on these. Some of the shades are a bit too close for me. The regulator is L7805CV and has 83275 below.

Edited May 13, 2011 by zylon

[Pilsner73]

I am trying to get Best to give me an idea but he's a 20 dollar minimum order value, I can find the regulators and capacitors but the resistors are giving me trouble finding what I believe are the correct ones.

[zylon]

I am trying to get Best to give me an idea but he's a 20 dollar minimum order value, I can find the regulators and capacitors but the resistors are giving me trouble finding what I believe are the correct ones.

Those might be still good! The regulator and caps are the main failure points beyond the coils themselves. You might be able to get good readings from the resistors and ID them that way. I've never done so. I'm mostly self-taught on electronics and was never good at checking resistors or caps. I just read, remember, and experiment and it usually gets the job done. The PS I found must be a different revision since it has locations for parts that aren't there. Small amounts of components can be found on ebay as well. The individual price may be higher, but not everyone would need a whole roll. Edited May 15, 2011 by zylon

[Pilsner73]

Yeah I talked to Best again and possibly found a few items to order to hit the 20 dollar order minimun but they claim not to have the resistors either. The outward appearance of the resistors look bad with burn type marks and missing color rings on another in the center. Would love to find out what parts are needed since these are the rebuild-able Atari power supplies and look fairly simple to work on.