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Atari 600XL black screen


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Check the solder connections to the chips performed during upgrade, make sure they haven't inadvertantly bridged multiple pins. Lightly lift then reseat those chips also.

 

Check the traces that had to be severed and ensure they're done properly.

 

Lift/reseat the 2 Ram chips.

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Check the solder connections to the chips performed during upgrade, make sure they haven't inadvertantly bridged multiple pins. Lightly lift then reseat those chips also.

 

Check the traces that had to be severed and ensure they're done properly.

 

Lift/reseat the 2 Ram chips.

 

I checked and found no issues. I decided though that I may return the machine to stock 16K to check if is still alive that way. If OK, then I will perform again the upgrade carefully.

Could the power supply be an issue? I will try to find one just to check and be sure.

 

 

Try swapping the delay line IC (U13) if you happen to have a socketed 800XL to hand. This chip is often the cause of spontaneous 600XL death.

 

This is quite difficult at the moment... I have no other 8bit machine from Atari near.

As I already mentioned, maybe tommorow I should return the board to stock condition and start from there...

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  • 4 months later...

The IC designations in SAM’S are usually by “U number” as printed on the PCB silkscreen. The 600XL and 800XL have different board layouts so they’re analogous but not identical. Is there a SAM’S for the 600XL? If there is, it’s probably on Atarimania. 

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Hi, thanks for your response. I do not think there is a SAM’s for the 600xl. It is definitely not in Atarimania. 

I think can correctly identify each ic based on schematics on both models. Map them correctly. 

 

I would like to know if I should expect to see the same readings on the logic probe if I follow the logic chart for the 800xl in the 600xl.

 

The atari 600xl field manual is not very good to troubleshoot. So I am trying to find the best way to find what is wrong with this machine without doing the Swapping dance....

 

I do not have a scope in my tool box.

 

thanks a lot!!!

Al

 

 

 

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Happy to report my new 600xl has been fully repaired. I used the logic probe with the 800xl/600xl charts and aided my troubleshooting with an atari 5200.

 

I ruled out gti, 14806 and pokey with the 5200. 

14806 was bad.

After replacing it, I was still getting black screen.

I had an extra Rom and basic chips, which I tested. Both ok.

Then I checked most of the small ic’s, all ok.

I finally got to the pia Ic, it was bad.

Machine boot up and is working great. I cleaned it. Cleaned the keyboard and recap it.

 

Thanks all and good luck!

Al

 

 

image.jpg

Edited by alortegac
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"14806" is the 6502 SALLY CPU chip, so you had a bad CPU and a bad PIA? That's an unusual combo of parts to be bad on one machine but anything is possible in a 35 year old computer.

 

Anyway glad you got your computer running again! :) 

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  • 6 months later...

I have a 600 XL that I knew to be dead when I bought it.   I finally dug out my fully socketed 800 XL and swapped chips into it one at a time.  When I swapped the CPU in, the 800 XL failed to boot and just sat there with a black screen exactly like the dead 600 XL.  For completeness I swapped in all the other major chips and the only other one that failed to start was the POKEY chip which got to a blue screen with a cursor before hanging.

 

So the big question is who do I go to for replacements for these parts.  I've heard that the POKEY chip is getting rare because of the stereo mods.  Does Best Electronics have any remaining POKEY chips?  SALLY chips?  I really want to get the 600 XL up and running without having to sacrifice the 800 XL.

 

Now that I know which chips are trashed, can I expect new chips to work in the 600 XL?  I don't know what killed the original chips but I suspect that the power supply may have been the culprit.  I didn't receive a power supply with this PC, but I have a "Black Beauty" and a "White Beauty" PSU that I would pair with the 600 XL if I get it running.  Are there any other vulnerable chips that I should try on the 800 XL before trying to boot the 600 XL with a working CPU?

 

Any recommendations are welcome. 

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BEST and B&C Sell POKEY chips for about $20 a pop. Maybe you can find a 7800 ballblazer cartridge, or another dead machine cheaper... :?

Both would also have SALLY chips. In fact, here's a current listing B&C has on eBay for $10 each: https://www.ebay.com/itm/143371502825

 

The chips are fully interchangeable between most XL's and XE's. The only risk is variants of the ANTIC chip sometimes, the 1200XL and 800's had a variant that refreshed RAM differently which is incompatible with RAM in later XL/XE's.

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Fortunately the Antic chip was not one of the bad chips. 

I haven't swap any of the smaller chips yet like the delay line and LS series chips.  I'm thinking I'll take a chance on firing up the 600 on the 800's CPU and POKEY chips and see if there are any other problems that crop up.  At least I'll have a complete list of parts when I go shopping.  If I can get the 600 running, I already have the 64K rams ready for an upgrade. 

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The 600 XL still doesn't start up with replacement CPU and POKEY chip.  It still comes up with a black screen with a few white thin horizontal lines on the left side.  At least it didn't fry the other CPU and POKEY.  I guess I go through the small chips and look for any other issues on the board.  I wonder what hit this computer to cause this much damage?  A power surge?  I see no signs of fluid incursion.

Is there a book that lists common faults based on what appears on the screen?  I seem to recall reading something that specifies which chips or components to check based on screen color or pattern.  I scanned through the SAMS and the Field Service manuals but didn't see anything. 

 

[EDIT]  The above may be something I saw on a C64 site. [/EDIT]

Edited by Geister
aging memory circuits
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7 hours ago, Geister said:

It still comes up with a black screen with a few white thin horizontal lines on the left side.

Vertical bars indicates the GTIA is probably OK, generating a video signal with a stuck player or missile, but not getting any data from the rest of the system.

 

When you press RESET, do you hear it click if you turn up the volume?

 

You might have a bad OS ROM, or MMU. Try swapping those next.

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The GTIA is good because it worked fine when I switched it into my 800 XL.  The ROMs are also good for the same reason.  I'm not sure about the MMU or delay line, I haven't swapped them yet.

 

I will try swapping them when I get access to the television set again.

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  • 4 weeks later...

The 600 XL is back among the living.  I ordered the 6502 and POKEY from B&C Computervision and while waiting for them to arrive, I swapped all the small chips into the 800 XL where there was an analogous part.  They all worked perfectly.  The only chips I hadn't swapped were the 74S32 and the two RAM chips. 

 

I tested the 74S32 by plugging it into a prototype board and hooking the outputs to some ancient LEDs and resistors and wiring the inputs to 5 volts and ground.  All 4 gates followed the truth table exactly so it was working.  

 

When the CPU and POKEY arrived I powered the board up and still no picture.  Just a black screen with dancing vertical color wisps.  I took the movement to mean that the CPU and video chips were alive and since all the other chips I tested were good I thought it was either the ram or some discrete component in the video circuit.  I had purchased some 4464 compatible rams prior to testing in hopes of upgrading the memory, so I plugged them in to see if they made a difference.  The computer came up with the familiar blue screen but no sound and no "READY", just the cursor.  I had seen that behavior when I tried the dead POKEY in the working 800XL so I checked the new POKEY chip.

 

Sure enough, the pins on the new POKEY chip were splayed enough that they had completely overshot the back side of the socket and I hadn't even noticed.  When I rolled the pins and plugged it back in, the computer booted up, farted at me and said it was now "READY".  Hoooo-rah Victory!

 

Sorry I didn't film anything (or think to take pictures).  Hopefully, the above descriptions will help guide someone trying to resurrect a dead 600 XL.  It really does help to have a second working computer to swap parts into.  It saves a lot of time poking about with a logic probe.

 

This morning I hope to run the wires to make this a 64K machine and then start ordering parts from Lotharek (or his US distributor, Amiga on the Lake).  I wanted to do a U1Meg upgrade, a UAV, and a SIDE 2 cartridge...until Jon uploaded his SIDE 3 preview.  Now I have to wait for a SIDE 3.  Just kidding I'll still get the SIDE 2 until the 3 comes out.

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Actually, I didn't bridge anything, I had a cold solder joint on one of the wires in the via's. A touch of the soldering iron and she booted right up.  I had to borrow the keyboard from my 800 XL just to run the self-test because the 600's keyboard Mylar is in bad shape.  As soon as I turned on the computer with the keyboard plugged in it started repeating "5" across the screen.  

 

With the swapped keyboard, a "PRINT FRE(0)" returned 37902, so I think the ram upgrade took.  Nothing but green blocks on the ram test!   

 

Getting there!   

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I took the keyboard apart and wiped it down with alcohol and a micro-fiber towel.  When I reassembled it I replaced the failed tape holding the cable end together and after some tweaking to get the function keys to work freely, everything is working.  I may still need a new membrane for the keyboard, but not tonight.  Time to order the U1MB and a UAV board.

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