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Troubleshooting XL computers

600XL 800XL

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#1 Keneg OFFLINE  

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Posted Thu May 24, 2018 7:28 PM

I now have two Atari computers. The 600XL that I was trying to get th3 keyboard working on and then I quit working altogether. I tried buying another off eBay. It was advertised as a 600XL, but turns out to be an 800XL. That would be great if it worked. The weird thing is that they both display the same symptoms. With one power supply, I get colors flashing across the screen and a hum from the sound. Using th3 other power supply, I get top half of screen black and the bottom very snowy, mostly white. I have a multimeter and a logic probe. I figure the first step is to check power supply voltages. Then what next? Is the test cartridge sold by Best Electronics any good?

#2 adam242 OFFLINE  

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Posted Thu May 24, 2018 8:26 PM

That hum is not a good sign... Some variants of the XL power supply are failure-prone and can damage the computer when they go. Check both power supply voltages before you power either machine on again.



#3 seastalker OFFLINE  

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Posted Fri May 25, 2018 9:56 AM

Just got two fully socketed 600xls.  Using a new power supply, one 600 is not working and I swapped all chips out (and thus reseated) and the good one found three bad chips on the bad:  ANTIC (CO21697), CPU Sally 6502C CO14806 and the old odd legged CO60472-D (Delay). After putting them aside, I put the GOOD versions from the working board into the bad hoping I'd just need the three chips to fix it. No dice. Now, it powers up to an odd screen I'd not seen before (pix soon). I was hoping not to desolder willy nilly.

 

1. Any way to tell a PAL 600xl from an NTSC one?

2. I followed the Black screen/Red screen guides from http://atari.boards.net/thread/893/black-screen-problems-fix-checklist so all steps from Star Raiders to channel 2-3 moving tried.

3. Any next troubleshooting steps?  I can try the clock timer if my pics look like that may be the issue. 



#4 Keneg OFFLINE  

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Posted Fri May 25, 2018 4:05 PM

That hum is not a good sign... Some variants of the XL power supply are failure-prone and can damage the computer when they go. Check both power supply voltages before you power either machine on again.


Interesting update. I checked voltages today. The power supply I got with the 600XL that turned out to an 800XL tested at 3.9 volts. So I didn’t bother turning on the computer. I switched to the power supply that came with the 609XL and it tested at 5.16 volts. When I turned on the computer to check the voltage with it running, to my dismay, it powered on to basic! Since I had the keyboard off, I tried shorting pins at the connector and got characters on the screen. Fantastic!

So then I tried the 800XL with the good supply. It works great, both RF and composite. Once I figured out that the red wire is video and not sound. So I have a working 800XL and a repairable 600XL. What I was beginning to think was a huge waist of money now looks like a bargain.

So, I know I can buy parts from Best Electronics. Is this my best option for a power supply? I’m thinking I should buy two and not rely on the one that seems to be working now.

#5 DrVenkman OFFLINE  

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Posted Fri May 25, 2018 4:30 PM

The low-voltage PSU may have indeed suffered an internal failure, taking the machine down with it on the way.

 

If you want to repair that machine and not just use it for spare, you'll have to take it apart and do some work. First off, with a good PSU connected (see below), power on the machine, wait a few minutes and then see if any of the components get substantially hotter than the others. Pay special attention to the RAM, as it's often affected first by a failing power supply. If that pragmatic test doesn't ID any obvious culprits, and you don't see anything else obviously amiss, you'll need to take other steps. 

 

There are two main approaches: chip swapping is easiest and fastest way to identify and fix most problems with XL machines. Alternately, you can google up schematics (the ones in SAM'S COMPUTERFACTS for the XL machines are quite good), power up the board and start checking with your meter and/or logic probe until you find something suspicious - smart folks here will help you eliminate false alarms and verify truly anomalous results. If you decide to swap chips, swap FROM the good machine into the bad, not vice versa. If whatever killed the machine in the first place isn't definitively ID'd, it's possible you might damage a good component if you try it in the bad machine.

 

To that end, make sure to use a known-good PSU for your tests. This is a photo I nicked from B&C ComputerVisions ebay listings (seller name 'myatari'). I've annotated it with a red circle to indicate PSU's you should avoid at all costs. That one is known colloquially as "the ingot" and when it fails, it tends to spike high and damage the machine it's plugged into. I have a few of them, but only as donors for the DIN pigtails I'll someday cut off and wire to modern 5V DC power supplies. The other models shown are generally all fine.

 

XL Power Supplies.jpg

 

 



#6 Fox-1 / mnx OFFLINE  

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Posted Fri May 25, 2018 6:07 PM

So, I know I can buy parts from Best Electronics. Is this my best option for a power supply? I’m thinking I should buy two and not rely on the one that seems to be working now.

 

Do yourself a favor and get a modern 5VDC power supply (at least 1.5A but 2A or a bit more is better).  Snap the cable with DIN from a broken one and connect it to the new one.



#7 Keneg OFFLINE  

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Posted Fri May 25, 2018 6:40 PM

Do yourself a favor and get a modern 5VDC power supply (at least 1.5A but 2A or a bit more is better).  Snap the cable with DIN from a broken one and connect it to the new one.


The one that is now working wasn’t before. I suspect this indicates a problem with the cable or connector as it gave black screens with two computers when it wasn’t working. Suddenly it is working again today. I will probably buy a couple from Best Electronics. I am trying to decide between buying the keyboard mylar from them or, for slightly more, the entire keyboard. I tried in a couple of example BASIC programs today. The keyboard takes a bit of getting used to, but the programs worked fine. The 800XL passed all self tests.

I also need to decide on a storage option. I am aware of the SIO2SD and SIO2USB. Are there other options. I don’t think I want to mess with a real floppy drive.

#8 xrbrevin OFFLINE  

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Posted Sat May 26, 2018 12:32 AM

correct me if im wrong - to distinguish an NTSC from a PAL 600XL: the NTSC version does not have a monitor port



#9 Fox-1 / mnx OFFLINE  

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Posted Sat May 26, 2018 3:35 AM

I will probably buy a couple from Best Electronics.

I also need to decide on a storage option. I am aware of the SIO2SD and SIO2USB. Are there other options. I don’t think I want to mess with a real floppy drive.

The power supplies you buy from Best are about as old, or even older, as the ones you already have.  Sure, they may be unused but things like capacitors wear out anyway.  If a true authentic, all Atari, set-up is what you want, that's the way to go.

 

If you want one that runs cooler, is smaller, is easier available and replaceable, energy-saving and cheaper, then go for a modern solution.  Or at least consider it.  You can also source the power from a PC system but that's only practical if you have one nearby which usually runs anyways.

 

Most versatile disk drive replacement is a SIO2PC, either by RS232 (older systems) or USB connection, with the Aspeqt/Respect software.  Can't go wrong with that and you can always add other devices later on.



#10 Fox-1 / mnx OFFLINE  

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Posted Sat May 26, 2018 3:40 AM

correct me if im wrong - to distinguish an NTSC from a PAL 600XL: the NTSC version does not have a monitor port

Or check the ANTIC

 

CO21698 is PAL

CO12296 or CO21697 is NTSC



#11 Keneg OFFLINE  

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Posted Sat May 26, 2018 7:34 AM

correct me if im wrong - to distinguish an NTSC from a PAL 600XL: the NTSC version does not have a monitor port


Yes, that is correct. When I bought the 600XL that turned out to be an 800XL I thought I had a PAL 600XL until I looked at the sticker on th3 bottom. I think you can convert them, but I don’t know how involved that is.

#12 Keneg OFFLINE  

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Posted Sat May 26, 2018 8:15 AM

The power supplies you buy from Best are about as old, or even older, as the ones you already have.  Sure, they may be unused but things like capacitors wear out anyway.  If a true authentic, all Atari, set-up is what you want, that's the way to go.
 
If you want one that runs cooler, is smaller, is easier available and replaceable, energy-saving and cheaper, then go for a modern solution.  Or at least consider it.  You can also source the power from a PC system but that's only practical if you have one nearby which usually runs anyways.
 
Most versatile disk drive replacement is a SIO2PC, either by RS232 (older systems) or USB connection, with the Aspeqt/Respect software.  Can't go wrong with that and you can always add other devices later on.


OK, thanks for the reply. I was looking at the SIO2USB mostly because it is low cost and I have some spare laptops that could be used with it.

Just to check before I buy. There are 5v 2a power supplies available on Amazon and eBay. It looks like I could just cut the cord off of my defective supply and the plug from the new supply and splice the wires. Just have to get the polarity right. Is that what you are suggesting?

#13 Fox-1 / mnx OFFLINE  

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Posted Sat May 26, 2018 9:00 AM

It looks like I could just cut the cord off of my defective supply and the plug from the new supply and splice the wires. Just have to get the polarity right. Is that what you are suggesting?

 

Exactly that.

 

Just be very sure the polarity is right.  Double check, triple-measure, I guess you get it :-)



#14 Keneg OFFLINE  

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Posted Sat May 26, 2018 2:41 PM

Exactly that.
 
Just be very sure the polarity is right.  Double check, triple-measure, I guess you get it :-)


It’s been a while, but I do know some basic electronics. I have an SIO2USB and USB ordered. I will order a couple of the power adapters now. Thanks for the help. I did fix the keyboard of the 600Xl, mostly. Here is what I posted about that.

It turns out that is was the keyboard mylar. Near the power light there are two contacts. They were black. Cleaned them and reassembled the keyboard. It works! If only I hadn’t lost one of the springs. So the help key doesn’t work. All other keys work fine. So does anyone know where I can get one of these springs? I need the steel one that is used for the right side keys. The rest of the keys use copper or brass springs.

One note. On both the 600 and 800XL, entering the keyboard test from “All Tests” does not work right. I have to select it separately. Then all keys, except “Help” work fine.

#15 Fox-1 / mnx OFFLINE  

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Posted Sat May 26, 2018 2:53 PM

One note. On both the 600 and 800XL, entering the keyboard test from “All Tests” does not work right. I have to select it separately. Then all keys, except “Help” work fine.

 

If you mean that it doesn't show the pressed keys...  that's normal behavior.  The "all tests" is more like a demo thing than a testing tool.



#16 SS OFFLINE  

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Posted Sat May 26, 2018 5:00 PM

Here is a quick and easy tool that includes a keyboard test.

Attached Files



#17 Keneg OFFLINE  

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Posted Sat May 26, 2018 10:38 PM

If you mean that it doesn't show the pressed keys...  that's normal behavior.  The "all tests" is more like a demo thing than a testing tool.


The built in keyboard test seems to work fine when selected by itself. Just not when run as part of all tests. I was able to verify all the keys on both computers once I figured that out.

#18 seastalker OFFLINE  

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Posted Tue May 29, 2018 1:02 PM

My post #3 on this page I'm updating with pictures.  I mentioned having bad CPU Sally 6502C CO14806 and the old odd legged CO60472-D (Delay). When replacing them with known good ones, I STILL get the screen as pictured. Anyone seen this before and know what to do on a fully socketed 600xl with all tested and working chips?

 

A clue may be in sorting what may have caused the 3 chips to fail but the 600xl was given to me so I don't know the history.  Bad PSU? Loose socket? Bad crystal?

 

 

Attached Thumbnails

  • 1.jpg
  • 2.jpg

Edited by seastalker, Tue May 29, 2018 1:02 PM.


#19 Keneg OFFLINE  

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Posted Thu May 31, 2018 8:05 PM

Today I got my Star Raiders cartridge. I plugged it in even though I don’t have a joystick. It worked, but just before I was going to shut off the computer, there must hav3 been a lightning hit nearby. The power was out for a second or two. Now the 800xl won’t boot with the cartridge in and the ram test only shows 40 blocks instead of 48. The screen color seems a little off also. Obviously I need to get and use a surge suppressor. Is this likely just one or more fried ram chips or something else? To be clear, th3 ram test doesn’t show red blocks for the missing 8k, it pauses for a few seconds at 40k and then rechecks the roms. Also, what ram chips would I need? I know they are different than the 4164s in the 600XL.

#20 Fox-1 / mnx OFFLINE  

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Posted Fri Jun 1, 2018 3:39 AM

It worked, but just before I was going to shut off the computer, there must hav3 been a lightning hit nearby. The power was out for a second or two. Now the 800xl won’t boot with the cartridge in and the ram test only shows 40 blocks instead of 48. The screen color seems a little off also. Obviously I need to get and use a surge suppressor. Is this likely just one or more fried ram chips or something else? To be clear, th3 ram test doesn’t show red blocks for the missing 8k, it pauses for a few seconds at 40k and then rechecks the roms.

 

You really should repair it.  The 800XL's with those special keyboards are really rare.

 

key800xl-1.jpg



#21 seastalker OFFLINE  

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Posted Fri Jun 1, 2018 7:09 AM

Hope I am not hijacking the thread- thought it might be not an individual troubleshooting one and more of a home for anyone with a troubleshooting issue.



#22 xrbrevin OFFLINE  

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Posted Fri Jun 1, 2018 9:34 AM

Today I got my Star Raiders cartridge. I plugged it in even though I don’t have a joystick. It worked, but just before I was going to shut off the computer, there must hav3 been a lightning hit nearby. The power was out for a second or two. Now the 800xl won’t boot with the cartridge in and the ram test only shows 40 blocks instead of 48. The screen color seems a little off also. Obviously I need to get and use a surge suppressor. Is this likely just one or more fried ram chips or something else? To be clear, th3 ram test doesn’t show red blocks for the missing 8k, it pauses for a few seconds at 40k and then rechecks the roms. Also, what ram chips would I need? I know they are different than the 4164s in the 600XL.

 

are you entering self test via basic? i.e. by typing "bye" or "b." - if so, basic will occupy RAM and the self test will only show 40 blocks

the way to show all 48 blocks is to power on (with no disk drive attached) whilst holding down the option key to enter the self test via no basic

 

also, if your atari loads star raiders ok, it implies that your OS ROM is defective. you can buy another (some bloke on UK ebay sells them reasonably cheap) or i believe you can burn your chosen OS onto a blank EPROM but the only guides ive found on here are for doing so with advanced features - i can't find a guide to burn just 1x simple standard OS :(

 

ive started a new thread to see if there is an easy way to do it :)


Edited by xrbrevin, Fri Jun 1, 2018 9:43 AM.


#23 Fox-1 / mnx OFFLINE  

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Posted Fri Jun 1, 2018 9:56 AM


 

 i can't find a guide to burn just 1x simple standard OS :(

 

Step 1: Burn the 16KB O.S. in a 16KB EPROM and exchange it with original ROM.

Step 2: There's none

 

That's all it takes and probably the reason why there's no how-to guide.  People who can, and know, how to burn an EPROM know what to do but in case they don't, feel free to ask.

 

 

 

 

 

 

 



#24 xrbrevin OFFLINE  

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Posted Fri Jun 1, 2018 11:49 AM

thanks - i bet youre right. its so uncomplicated, there is no guide!



#25 Keneg OFFLINE  

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Posted Sun Jun 3, 2018 11:14 AM

are you entering self test via basic? i.e. by typing "bye" or "b." - if so, basic will occupy RAM and the self test will only show 40 blocks
the way to show all 48 blocks is to power on (with no disk drive attached) whilst holding down the option key to enter the self test via no basic
 
also, if your atari loads star raiders ok, it implies that your OS ROM is defective. you can buy another (some bloke on UK ebay sells them reasonably cheap) or i believe you can burn your chosen OS onto a blank EPROM but the only guides ive found on here are for doing so with advanced features - i can't find a guide to burn just 1x simple standard OS :(
 
ive started a new thread to see if there is an easy way to do it :)


I actually made some progress with both computers today. I got in the 5v, 2a power supply. The 600XL was coming up with a black screen if the keyboard was plugged in. With the new supply, it boots, the colors are right, but the main keyboard keys don’t work.

On the 800XL, it now shows all of the ram, but the screen colors jump around. I didn’t know about the difference in the memory test if you run it out of BASIC, but I am doing cold boots with option key held down. Good information to have. The new power supply’s wires are only 22 gauge. Could that still be the problem? Seems really small to me and could be acting as a high resistance. On the 600XL, the voltage is 5.17 switch off and 5.00 switch on. I didn’t think to try to check the voltage with a key pressed down. I don’t have the 800XL apart to check voltages.





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