Problem with Atari 800XL

[fogofo]

Hi Everyone.

I'm writing to ask you something, maybe you can help me. I found an old and dear Atari 800XL from my childhood and i want to know how i can fix it because in that time (about 20 years ago) it had a problem that could never be solved.

The problem is the following: when i load a game from tape recorder, i spend some time playing and then suddenly the screen starts to change its color, for example, the blue screen with "Ready" turns green, then red and finally appears a black frozen screen and a lot of characters filling all the screen (in certain forums they called garbage screen),then to play again i must wait some period of time, load another game, play a little time and crashes again. Some people says that maybe is a problem with the ANTIC Chip but i don't know how to test it.

I opened the case and there's no sign of something bad or burned in the main board, so i measured the voltage inside the Atari and i found that the voltage drops slowly, and reaches a point where there is only 3.70 volts which coincides with the black screen, i suppose that by failing to maintain the correct voltage, it stops working. I have tested the plug power supply and gives me 5.04v (i think is normal), so i opened the power supply and found that there is a leakage from a capacitor, i have changed it for a new one, but the problem remains. The basic diagnostics (memory , sound and keyboard) don't have any error.

Unfortunately, there's no technical services who repairs this machine near of my residence (by the way i'm from Chile). I was searching and found an Atari 800XL field service manual on the Internet and they said something about a catridge called "Super Salt diagnostic Catridge" that suppose to do a diagnostic test on every internal part to find what is the failure. So, my questions are:

¿Where can i find a copy of Super Salt catridge?
¿Do you Know what could be the problem with the 800XL and how can i solve it?
¿Is there any PC software similar to Super Salt that can be used on 800XL, maybe connecting both machines via parallel o serial port?
¿Is there any Basic OS algorithm to use instead of Super Salt (In case i can't find it)?.

It's my first time here in Atariage's forum, i'm really interested in fix it, only to have the pleasure of playing again those great games. Thanking you in advance for your answer.

[AtariGeezer]

I would change all electrolytic capacitors in the power supply and maybe the voltage regulator too...

[fogofo]

 

I would change all electrolytic capacitors in the power supply and maybe the voltage regulator too...

 

Thanks for the answer. Based on that, ¿is it possible to use another 5v power supply and put it a 7 pin din plug? (I think that some routers have similar power supply voltage). And another question, ¿how can you check if a capcitor is in good state, without removing it from the main board?. I've tried to measure it with a multimeter with uF scale but without energy (power supply and atari off) and i don't know if i'm right.

 

i forgot to mention that recently i leave plugged the power supply for about 20 min. then i measured again the voltage in the pins and gives me 5.04v, but the problem starts when is plugged to the atari.

 

Thanks again.

[Osgeld]

 

And another question, ¿how can you check if a capcitor is in good state, without removing it from the main board?. I've tried to measure it with a multimeter with uF scale but without energy (power supply and atari off) and i don't know if i'm right.

 

you cant really cause every capacitor in paralell with the one you are measuring will add to the total value, but caps have poor tolerances anyway so as long as its something close

[Keatah]

It's possible that you could have a component that draws more and more current as it heats up, eventually "overloading" the supply. Who's say without further measurements..?

[fogofo]

 

you cant really cause every capacitor in paralell with the one you are measuring will add to the total value, but caps have poor tolerances anyway so as long as its something close

 

I will try to check all the capacitors in the power supply thanks. Some of them, gives me the real uF value printed in the capacitor, but others don't.

 

 

 

It's possible that you could have a component that draws more and more current as it heats up, eventually "overloading" the supply. Who's say without further measurements..?

 

And that component could be on the power supply unit or in the atari itself?. The last thing i've tried was check the resistor's values in the main board of the atari, based on the field service manual document. Some of them gives me the same value and others don't.

 

Thanks, and sorry for asking so much but i know only few things about electronic.

[fogofo]

Finally i found the problem, and it was the power supply unit, i adapted the original cable of the PSU to another power supply from an external hard disk case. I plugged it and keep it functioning about 40 mins without any problem, so i can discard an atari failure. Now i Would try to fix the original, and if is not possible, just change it for another one. Thank you all for your answers.

[Osgeld]

real adapters are not that rare, but then your using a 30 year old adapter heh, I dont know about repairs, Its been a while since I have seen a real atari model but many supplies are sonicly welded together. you can squash them a bit in a vice and they will pop open, but they might not want to go back together.

 

Inside you will find a transformer(to step the mains down to a low voltage AC source) some type of bridge rectifier (either diodes or a packaged device to convert AC to DC) and probably a fat cap or two (to smooth out the ripple from rectification), IMO its not really worth fiddling around with, and if you get a hold of the primary side of the transformer while plugged in, shocking.

 

you can find generic replacements all day long on ebay (9v 500ma) for 7-10 bucks.. getting one from a electronics supplier is about the same, but you can go back to them for a good amount of time and get the same uint... like this cute little high efficiency switching model from digikey

 

http://www.digikey.com/product-detail/en/EPS090066-P1P/T979-P1P-ND/1016855

Edited January 18, 2014 by Osgeld

[ApolloBoy]

you can find generic replacements all day long on ebay (9v 500ma) for 7-10 bucks.. getting one from a electronics supplier is about the same, but you can go back to them for a good amount of time and get the same uint... like this cute little high efficiency switching model from digikey

 

http://www.digikey.com/product-detail/en/EPS090066-P1P/T979-P1P-ND/1016855

I wouldn't use that, 500 mA isn't quite enough current for an 800XL and feeding an 800XL 9V is a sure way to kill it.

[Osgeld]

ah my bad, I got my models crossed, its too late to edit so ignore everything I said pas the second paragraph

Edited January 18, 2014 by Osgeld

[ApolloBoy]

ah my bad, I got my models crossed, its too late to edit so ignore everything I said pas the second paragraph

9V DC wouldn't work for an original 800 either, since it uses 9V AC to generate 5V DC, 12V DC and -5V DC.

[Osgeld]

I didnt say which models lol, you gots me, be happy, it only happens daily

[+wood_jl]

Most of the 800XL power supplies are the "bad" version, commonly referred to as "the ingot," due to its shape. They're *known* to go bad, and there are some threads here about that problem,as it comes up from time to time.

 

As that power supply is internally encased in solid epoxy, it's not easily serviceable, so I don't know how one would go about replacing the components inside it. As has been suggested, replace it. I had many years (most of them earlier years) transpire without this problem occurring, until it finally did one day. I thought the machine was "toast." Just buying a replacement (silver-label model that was frequently shipped the model 130XE computer) made it work! I consider myself fortunate, as the faulty power supply can damage components in the 800XL. In my case (luck?), it did not, and replacing the power supply made a wonky machine work!

 

I'd first get a replacement (not "the ingot") power supply. There's a chance that's the entire problem and the 800XL itself could work. Even if there's damage to the 800XL, you're going to need a better power supply either for your future-repaired 800XL, or a replacement 800XL that you procure that more than likely will ship with the same defective power supply. The "ingot" power supply is, evidently, a ticking time-bomb even if it works when you first receive a working machine with one.

 

Here's a picture of all the original XL/XE power supplies, from B&C Computervisions. This image has been tossed-around here a few times, so it's not to my credit:

 

 

I like the one in the upper-right corner, as it's no larger than the original 800XL supply that goes "bad" (top middle). Note they used the same part number (CO61982) on a few power supplies (even the 2 huge ones on the left of the above picture.

 

I like the silver-labeled one:

 

 

 

Here's a side-view of "the bad Atari ingot"......

 

 

....and an actual ingot, from which it derives that nickname!

 

[RickR]

I've got a "White Brick" power supply that behaves the same as OP's. It works fine for about 20 minutes, then just dies...probably due to heat. Any idea on how to repair such a thing?

[fogofo]

I have the bottom-left corner's power supply (first image of Wood_jl) luckily it was easy to open and see their components.