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Prolonging Atari 800XL life


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#1 Mrarkus OFFLINE  

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Posted Thu Jan 11, 2018 7:14 PM

Just got my hands on a like-new 800XL, and I've started researching how to keep it going for a long time. With my Commodore 64, it's a fairly common process of putting heatsinks on most of the major chips, especially in the breadbin models. Reading up on the 800XL though, I have not found anything of that nature, and even the RF shield (I'm assuming it's ok to toss?) doesn't have little lips that touch any chips.

 

Is heatsinking not a thing on the 800XL? Or not as necessary? Any insight would be appreciated... 



#2 Nezgar ONLINE  

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Posted Thu Jan 11, 2018 7:19 PM

C64 chips are notorious for death by overheating. That's why Atari's are better. ;-P Just make sure you are using a trusted power supply. Look up previous threads about the 'ingot' power supply and make sure you aren't using that.

Since we only need +5V 1.5A or more, you can cut the cable off it if so, and connect it to a modern power supply or USB charger power source instead.

#3 DrVenkman OFFLINE  

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Posted Thu Jan 11, 2018 7:40 PM

C64 chips are notorious for death by overheating. That's why Atari's are better. ;-P Just make sure you are using a trusted power supply. Look up previous threads about the 'ingot' power supply and make sure you aren't using that.

Since we only need +5V 1.5A or more, you can cut the cable off it if so, and connect it to a modern power supply or USB charger power source instead.

 

Yes, exactly. Don't use the dreaded Ingot. It's more prone to failure than other models, and when it does fail, it fails "hot" and fries chips!

 

XL Power Supplies.jpg

 

Other than that, Atari computers are really well-made. Hell, most Atari stuff prior to 1984 are really well made (*). Chips are generally all socketed or mostly so, PCB's are well-made and easy to work on with a soldering iron without undue risk of damage, capacitors are reliable and long-lasting, most of the power supplied (Ingot excepted!) are stable and fail benignly when they do go ... 

 

In short, so long as your power supply is good, don't sweat it. Use your machine and have fun!

 

(*) The assets and much of the Atari intellectual property was sold off by Warner Communications in July 1984 to the Tramiel family holding company and the home products were thereafter produced by the new Tramiel-owned "Atari Inc." Cost cutting began in earnest - chips got soldered rather than socketed, PCB's got cheaper, products were repackaged for cheaper production costs, etc. 



#4 Mrarkus OFFLINE  

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Posted Thu Jan 11, 2018 7:51 PM

Thanks! I opened up the computer, it's a Rev. C, unfortunately while most chips are socketed, MMU and BASIC are not. And, of course I got the Ingot power supply with it... I do seem to remember that big tan Atari PS in my garage from a long time ago, I'll have to try and dig it out, as I'm not powering up the computer again. I had a "wonderful" experience once with a C64 PS that fried two of my Commodores.



#5 DrVenkman OFFLINE  

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Posted Thu Jan 11, 2018 7:56 PM

Thanks! I opened up the computer, it's a Rev. C, unfortunately while most chips are socketed, MMU and BASIC are not. And, of course I got the Ingot power supply with it... I do seem to remember that big tan Atari PS in my garage from a long time ago, I'll have to try and dig it out, as I'm not powering up the computer again. I had a "wonderful" experience once with a C64 PS that fried two of my Commodores.

 

I hear you on the crappy C64 PSU. One went bad on me just this past spring and killed my C64 breadbox. I didn't use the machine much but I had bought it about 15 years ago because my wife played games on one as a little girl. :(

 

Good news for you is, alternative Atari PSU's aren't hard to find. Chances are your MMU and BASIC chips are just fine and unless you expect or want to do an upgrade like the Ultimate 1MB board, you won't likely need to mess with either one of those chips.



#6 Level42 OFFLINE  

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Posted Fri Jan 12, 2018 6:04 AM

I remember that my uncle had mounted a fan on top of his C64 power supply. It was insanely loud, and I hated the fact that I couldn't fry my eggs on it anymore....
It was one of the many reasons that I did not want a C64 BITD.

Oh and.....yes, Atari had much better designed VLSI chips which do not require any form of heat sinking, they're SO cool 😎

#7 _The Doctor__ OFFLINE  

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Posted Fri Jan 12, 2018 7:21 AM

I remember my buddies neighbor was on his 3rd c64 inside of a year and a half... it wasn't till they bought that third one that they figured out they had to keep both the power pack and the commie cool... what a hunk of burning junk...



#8 AMenard OFFLINE  

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Posted Fri Jan 12, 2018 7:32 AM

In the good old day, I use to put my C64 PSU between the double windows during winter to keep it cool as it did overheat and cut out... Then I had a friend make me another one and that thing was a beast.



#9 kheller2 ONLINE  

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Posted Fri Jan 12, 2018 9:28 AM

Are there ways to fix the C64 power supplies so they are better or should I just hack together two Atari supplies (9V AC and the 5V DC) to feed a breadbin?  Would rather hack the C64 to only accept AC and create the 5V internally.



#10 _The Doctor__ OFFLINE  

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Posted Fri Jan 12, 2018 9:37 AM

with how hot the 64 runs internally and how often the chips fail, best to keep the heat out of the box!



#11 slx OFFLINE  

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Posted Fri Jan 12, 2018 1:51 PM

As posted elsewhere here, my son has been running a 130XE, not a notoriously well-built variant, for months at a time with only brief vacation breaks in between for at least three years without any ill effects so far. He's using a "modern" power supply, though.



#12 jmccorm OFFLINE  

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Posted Sat Jan 13, 2018 2:40 AM

Today I fired up and tested a dozen of my old Atari 8-bits. For testing, the 800XL/1200XL/130XE machines were connected to the Composite Video Input of an NTSC television via the monitor output connection on the back of the computer. Two of my 800XLs had screen issues. One was black-and-white (shades of grey, no color) and the other was flickering and changing colors from time-to-time as I was hitting keys on the keyboard or moving the machine.

 

Both, it seems, suffered from oxidation on the color adjustment potentiometer that is hidden below the RF shield. Are there any well-known fixes (for the very long term) for the variable resistor, or is the consensus that it is good enough to break it free of the oxidation with a number of back-and-forth rotations every few years? Or are my cases unusual enough that it isn't regularly seen?

 

Thanks all,

jmccorm



#13 DrVenkman OFFLINE  

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Posted Sat Jan 13, 2018 8:40 AM

Today I fired up and tested a dozen of my old Atari 8-bits. For testing, the 800XL/1200XL/130XE machines were connected to the Composite Video Input of an NTSC television via the monitor output connection on the back of the computer. Two of my 800XLs had screen issues. One was black-and-white (shades of grey, no color) and the other was flickering and changing colors from time-to-time as I was hitting keys on the keyboard or moving the machine.

 

Both, it seems, suffered from oxidation on the color adjustment potentiometer that is hidden below the RF shield. Are there any well-known fixes (for the very long term) for the variable resistor, or is the consensus that it is good enough to break it free of the oxidation with a number of back-and-forth rotations every few years? Or are my cases unusual enough that it isn't regularly seen?

 

Thanks all,

jmccorm

 

I've never had that particular problem (oxidation of the color pot) but if it were my machine, I'd take off the RF shield, clean the system entirely with isopropyl alcohol, then spray Deoxit (electrical contact cleaner with excellent oxidation-removal properties) into the color pot while rotating it through its range of travel several times. Then I'd wait a few minutes for everything to dry/evaporate and give the system a power up test while still disassembled to make sure that's the problem. Not entirely convinced of that diagnosis, myself, but this method will let you know if you've ID'd and fixed the problem. :)



#14 Mrarkus OFFLINE  

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Posted Sat Jan 13, 2018 8:51 AM

Turned out that my Option and Help keys were not working, and I got the crappy ver 4 keyboard. Learning the Atari ways fast! Anyway, cleaned the mylar and it all works now.

 

I also found another power supply in my "big box of goodies", it's the ribbed one in the bottom right. Is that one safe to use? I have a very distrustful relationship with epoxy-filled power supplies...



#15 DrVenkman OFFLINE  

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Posted Sat Jan 13, 2018 9:16 AM

 

I also found another power supply in my "big box of goodies", it's the ribbed one in the bottom right. Is that one safe to use? I have a very distrustful relationship with epoxy-filled power supplies...

 

Yes, that one should be fine. If you have a multi-meter, check the voltage to be sure. But aside from the dreaded Ingot, the rest of these tend to fail with low voltage and the machine just won't work. The Ingot fails "hot" and fries chips. 



#16 Gunstar OFFLINE  

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Posted Sat Jan 13, 2018 9:32 AM

A couple of weeks ago I decided to watch a video on restoring a C64. There was something in particular I wanted to see, which I can't remember at the moment, but a search led me to the C64 video. At the end of the video they attached heat sinks to all the majoy IC's. I'd never thought of it before, and I decided I was going to do that to my 1200XL.

 

Not that I've noticed a lot of heat from it other than the heat-sink, but with all the upgrades I've added and will continue to add, I felt it might be a good idea to do the heat-sink mod. Plus it looks cool. But now, after reading this thread I see that the heat-sink mod on the c64 was more necessary than precautionary!

 

I had a c64 for a short stint about a decade ago, a restoration subject, and I don't recall anything being overly hot, but I'd only play with it for like 20 min. at a time and I sold it after a few months.

 

I already added a home-made aluminum foil heat sink to my AtariMax Rambo board's GAL chip as I did notice it was hot. I also plan on installing a small 5V cooling fan to my 1200XL. All for longevity. Maybe it's overkill, but it's my hobby so...


Edited by Gunstar, Sat Jan 13, 2018 9:41 AM.


#17 DrVenkman OFFLINE  

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Posted Sat Jan 13, 2018 9:43 AM

The only A8 chips in XL or XE machines that tend to run hot - barring an internally-shorted chip - are the MMU and to a lesser extent the CPU. Yet in all my 9 XL/XE A8 computers, none of the MMU chips (or FREDDIE in the 130XE) have failed. By contrast, I've had a failed POKEY, two failed GTIAs and a failed ANTIC. All but one of the failed GTIAs were from the same machine, the 1200XL I restored last year. I think someone plugged in very wrong PSU into that badly abused machine, or maybe it suffered a household lightning strike in its prior life. *shrug*



#18 jmccorm OFFLINE  

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Posted Sat Jan 13, 2018 10:08 AM

I've never had that particular problem (oxidation of the color pot) but if it were my machine, I'd take off the RF shield, clean the system entirely with isopropyl alcohol, then spray Deoxit (electrical contact cleaner with excellent oxidation-removal properties) into the color pot while rotating it through its range of travel several times. Then I'd wait a few minutes for everything to dry/evaporate and give the system a power up test while still disassembled to make sure that's the problem. Not entirely convinced of that diagnosis, myself, but this method will let you know if you've ID'd and fixed the problem. :)


I didn't think that the diagnosis would be questioned. My experience (outside of Atari) is that post that once oxidized will revert back to their oxidized state again and again, so I'll take your advice on one board, and set the other aside for a few years to allow someone else confirm the diagnosis. I had assumed it was a known issue!

Thanks for taking the time to detail the remedy with such specifics!

#19 DrVenkman OFFLINE  

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Posted Sat Jan 13, 2018 10:33 AM

The color pot on an Atari adjusts the hue, not the intensity. There's some inter-relation of the properties, but it's not a saturation control. Colors changing as you type sounds like a physically-loose connection to me, either at the DIN jack, bad connection (broken wire) in the cable near the jack, or some kind of issue with the GTIA (which generates the color video signal). A power issue or bad connection to the chip might also cause that kind of symptom. Straight out B&W video sounds like an issue with the color signals from the GTIA where they feed into the composite output.

 

One thing both these problems might have in common is the 4050 hex buffer IC in the video circuit. These can and do fail. A partial failure can cause loss of color in the output. Most of the time these chips are socketed but a later-production 800XL might have it soldered it. 



#20 Mrarkus OFFLINE  

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Posted Sat Jan 13, 2018 10:33 AM

A couple of weeks ago I decided to watch a video on restoring a C64. There was something in particular I wanted to see, which I can't remember at the moment, but a search led me to the C64 video. At the end of the video they attached heat sinks to all the majoy IC's. I'd never thought of it before, and I decided I was going to do that to my 1200XL.

 

Not that I've noticed a lot of heat from it other than the heat-sink, but with all the upgrades I've added and will continue to add, I felt it might be a good idea to do the heat-sink mod. Plus it looks cool. But now, after reading this thread I see that the heat-sink mod on the c64 was more necessary than precautionary!

 

I had a c64 for a short stint about a decade ago, a restoration subject, and I don't recall anything being overly hot, but I'd only play with it for like 20 min. at a time and I sold it after a few months.

 

I already added a home-made aluminum foil heat sink to my AtariMax Rambo board's GAL chip as I did notice it was hot. I also plan on installing a small 5V cooling fan to my 1200XL. All for longevity. Maybe it's overkill, but it's my hobby so...

 

With C64, there is one major revision - breadbin, brown-style C64, and the newer, slimmer, light-color 64C. The later runs much cooler as it went from 12V to 9V on the 3 big chips, and merged a lot of other chips.



#21 Mrarkus OFFLINE  

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Posted Sat Jan 13, 2018 10:34 AM

 

Yes, that one should be fine. If you have a multi-meter, check the voltage to be sure. But aside from the dreaded Ingot, the rest of these tend to fail with low voltage and the machine just won't work. The Ingot fails "hot" and fries chips. 

 

Great, thanks! I now have two good power supplies then, and the Ingot went to the bottom of the pile...



#22 Gunstar OFFLINE  

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Posted Sat Jan 13, 2018 11:39 AM

 

With C64, there is one major revision - breadbin, brown-style C64, and the newer, slimmer, light-color 64C. The later runs much cooler as it went from 12V to 9V on the 3 big chips, and merged a lot of other chips.

It was the later 64C model they added heat-sinks to in the video I watched, maybe the people that made the video had heard of the earlier model's problem and assumed it was for their model as well. The one I used to own was an original bread-bin brown style C64. It will be the style I get when I get another C64, I'm not a fan of 64C/128 styling, nor Atari XE styling. I'm a fan of the older styles 400/800/XL and VIC/C64.



#23 _The Doctor__ OFFLINE  

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Posted Sat Jan 13, 2018 3:12 PM

 

Great, thanks! I now have two good power supplies then, and the Ingot went to the bottom of the pile...

The Ingot is for parts, cut it up, take cords, hammer the heck out of it, if parts survive keeps them.... you win in every way... the sheer joy and satisfaction of obliterating an ingot and saving lives does it for me 'every' time :)


Edited by _The Doctor__, Sat Jan 13, 2018 3:13 PM.


#24 jmccorm OFFLINE  

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Posted Sat Jan 13, 2018 5:01 PM

Colors changing as you type sounds like a physically-loose connection to me, either at the DIN jack, bad connection (broken wire) in the cable near the jack, or some kind of issue with the GTIA (which generates the color video signal). A power issue or bad connection to the chip might also cause that kind of symptom. Straight out B&W video sounds like an issue with the color signals from the GTIA where they feed into the composite output.

 
This directly contradicts my experience, so I performed an experiment to test one of the symptoms.
 
I took yet another 800XL which was operating properly, and I connected it in the same way (into the Composite Video Input of an NTSC television which is driven from the monitor output connection on the back of the computer). I adjusted the color pot fully counter-clockwise. The image went grayscale. The output was consistent with the other machine that I had diagnosed earlier as having an oxidized color pot (which consistently exhibited color-free output until the oxidized layer was broken apart).
 
You can repeat this experiment yourself with an NTSC machine or I can takes pictures and/or video, if it is helpful.

EDIT: Of note, the two color pots which were having issues both appear similar to each other, but are physically different than the one that did not have issues. I do not yet have enough evidence to suggest if a specific model of potentiometer is more vulnerable to oxidation issues.

Edited by jmccorm, Sat Jan 13, 2018 5:59 PM.


#25 _The Doctor__ OFFLINE  

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Posted Sat Jan 13, 2018 6:17 PM

if you think its the color pots just replace them, messing up more color potentiometers and their calibration/settings and disturbing their traces is silly






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