Jump to content
RSwipeCA

800xl Red Screen. I want to fix!

Recommended Posts

What do pins 39 and 40 show on the CPU (U8)?

 

What is on pin 29 of ANTIC (U7)?

 

Use the TTL setting.

 

Bob

CPU 39 is both RED/GREEN LED Lit plus pulsing beep and flashing Orange LED

CPU 40 is RED HIGH

ANTIC 29 is GREEN LOW

Share this post


Link to post
Share on other sites

OK - thanks.

 

What is GTIA (U17) pin 30?

 

Bob

U17 PIN 30 is GREEN LOW Pulsing beep Flashing Orange LED

 

Many thanks Bob.

Edited by RSwipeCA

Share this post


Link to post
Share on other sites

Oh... GTIA 30 and ANTIC 29 are in the same net, so they should be the same. This net is the Phase 02 clock and should be a 50% signal. The signal is from U18, fed from CPU 39, which is OK.

 

Care to guess? U18 is bad? What is on pins 12 and 13 of U18? Pin 12 should be the 02 clock from CPU 39 and 13 should be tied up to +5v through a 3K resistor (R19).

 

Bob

Share this post


Link to post
Share on other sites

Oh... GTIA 30 and ANTIC 29 are in the same net, so they should be the same. This net is the Phase 02 clock and should be a 50% signal. The signal is from U18, fed from CPU 39, which is OK.

 

Care to guess? U18 is bad? What is on pins 12 and 13 of U18? Pin 12 should be the 02 clock from CPU 39 and 13 should be tied up to +5v through a 3K resistor (R19).

 

Bob

U18 PIN 12 RED/GREEN LED Lit Pulsing Beep Flashing Orange LED - same as CPU 39.

U18 PIN 13 RED LED HIGH

Share this post


Link to post
Share on other sites

Pin 11 of U18 should look just like Pin 12. There could be a short in the pin 12 net or U18 could be bad.

 

Bob

Thanks Bob. Just got back from business trip. Will look into it and post findings.

 

 

Ok. Yes Pin 11 on U18 is GREEN LOW LED Pulsing Beep Flashing Orange LED and Pin 12 is RED/GREEN LED Lit Pulsing Beep Flashing Orange LED. Different.

 

I will now begin the process of socketing the remaining chips. I will then check one by one using my working XL.

 

Thanks for your help. Will let you know.

Edited by RSwipeCA

Share this post


Link to post
Share on other sites

Hey Everyone.

 

Sorry for the delay, I was away AGAIN with work. If we didn't need the money eh????

 

Anyway, it looks like we've cracked it! I got around to socketing the entire board - good practice with the solder sucker and the iron.

 

I started removing all the chips one by one and putting them into my good 800XL. It turns out that the only chip that 'kills' my good XL is the U3 C061618-16 8434FMM MMU.

 

I put my good C061618-16 into the bad XL and it displays the normal blue screen and READY prompt!!

 

Now, so far I have replaced with new, the U17, U7, and U8 chips. I don't know if this machine is now working because of a combination of the new chips and the good MMU U3 chip from my other machine or not. What I will do is swap back in the old suspect SALLY, ANTIC and GTIA chips one by one and see if it has any effect.

 

I now need to get my hands on a newC061618-16 8434FMM MMU chip. Where would be the best place to get one of those?

 

I have attached two images. The chip 'in socket' is the good one that works in both XL's. The chip placed on the board is the defective one. They have slightly different markings - same C061618 number though. Will I have to find the exact same 'Good' chip?

 

Question, can I use an Epprom burner to 'make' a new MMU? How does all that work?

 

I will keep you posted on the U17,U7,U8 swapping.

 

Thanks again guys. Looks like we brought another XL back from the trash can.

 

Damian.

post-40814-0-98178600-1418955480_thumb.jpg

post-40814-0-03499900-1418955540_thumb.jpg

  • Like 3

Share this post


Link to post
Share on other sites

Hey Everyone.

 

Sorry for the delay, I was away AGAIN with work. If we didn't need the money eh????

 

Anyway, it looks like we've cracked it! I got around to socketing the entire board - good practice with the solder sucker and the iron.

 

I started removing all the chips one by one and putting them into my good 800XL. It turns out that the only chip that 'kills' my good XL is the U3 C061618-16 8434FMM MMU.

 

I put my good C061618-16 into the bad XL and it displays the normal blue screen and READY prompt!!

 

Now, so far I have replaced with new, the U17, U7, and U8 chips. I don't know if this machine is now working because of a combination of the new chips and the good MMU U3 chip from my other machine or not. What I will do is swap back in the old suspect SALLY, ANTIC and GTIA chips one by one and see if it has any effect.

 

I now need to get my hands on a newC061618-16 8434FMM MMU chip. Where would be the best place to get one of those?

 

I have attached two images. The chip 'in socket' is the good one that works in both XL's. The chip placed on the board is the defective one. They have slightly different markings - same C061618 number though. Will I have to find the exact same 'Good' chip?

 

Question, can I use an Epprom burner to 'make' a new MMU? How does all that work?

 

I will keep you posted on the U17,U7,U8 swapping.

 

Thanks again guys. Looks like we brought another XL back from the trash can.

 

Damian.

Your good MMU is a manufactured CO61618, the bad MMU is a programmed PAL 16L8(this was done in the early XL machines, though the PAL is dated coded one year later than the other). The MMU source code for GAL/PAL can be found at: http://www.atarimax.com/jindroush.atari.org/achmmu.html

 

There are probably some users here who have a surplus CO61618, when a U1MB upgrade is installed the MMU chip is no longer required. You could also purchase a U1MB, available from Lotharek, to eliminate the need for an MMU.

  • Like 3

Share this post


Link to post
Share on other sites

Cool, good to read your success story. I too have partial success with my 130XE. it also came from dead (from the red blank screen to a READY prompt) but is not stable yet and crashes randomly, I haven't tried it with a different MMU so far, so that will be my next swap, hoping to rescue this 130XE and have a fully socketed motherboard in the process.

Edited by atari8warez
  • Like 1

Share this post


Link to post
Share on other sites

Looks like check ram and then mmu for the failure to init symptoms in this scenario. Red screen of death be gone!

  • Like 1

Share this post


Link to post
Share on other sites

Looks like check ram and then mmu for the failure to init symptoms in this scenario. Red screen of death be gone!

I forgot!!! I also changed the RAM chips as a couple of them were almost too hot to touch in the beginning.

 

But yes, its looking good! Will keep you posted on the chip swaps guys.

Share this post


Link to post
Share on other sites

Finally got the 130XE working stable. It was not a MMU problem but bad RAM which is actually passing built-in memory test but failed during operation due to some kind of interference!. I've never seen that happen before. If I move my hand or another body part over the bad RAM chip it will somehow pick-up interference, my body acting like an antenna, and the interference crashes the computer. So when my hands were off the computer it worked, other times it crashed.

 

One common thing about the bad RAM chips is that they were all 256K and were previously used in a Scott Peterson 512K memory upgrade.

Here's a video of the problem. Did anyone experience this before?

 

Edited by atari8warez
  • Like 2

Share this post


Link to post
Share on other sites

Finally got the 130XE working stable. It was not a MMU problem but bad RAM which is actually passing built-in memory test but failed during operation due to some kind of interference!. I've never seen that happen before. If I move my hand or another body part over the bad RAM chip it will somehow pick-up interference, my body acting like an antenna, and the interference crashes the computer. So when my hands were off the computer it worked, other times it crashed.

 

One common thing about the bad RAM chips is that they were all 256K and were previously used in a Scott Peterson 512K memory upgrade.

Here's a video of the problem. Did anyone experience this before?

 

Looks to me like you are possessed with the evil Commodore spirits! Are you a Sith?

 

In all seriousness, I've not seen that before. Bad ground on the machine perhaps? Did you try doing that on an anti-static mat while you and the machine were properly grounded?

 

Anyhow - congrats on saving another machine from the trash heap.

  • Like 1

Share this post


Link to post
Share on other sites

Looks to me like you are possessed with the evil Commodore spirits! Are you a Sith?

 

In all seriousness, I've not seen that before. Bad ground on the machine perhaps? Did you try doing that on an anti-static mat while you and the machine were properly grounded?

 

Anyhow - congrats on saving another machine from the trash heap.

 

:)

 

Had that been a grounding issue wouldn't the same problem happen with all chips (including the good ones). To me it is definitely a RAM issue, I just never seen anything like that before. In the video I use the last socket to demonstrate bad chips, remaining sockets have all good chips and there is no issue with them (there was until i replaced them). I tried several of those 256K chips and they were all bad, some were causing the computer to boot into memory test mode, some where fine until i touched them. Anyway I ended up using some of the infamous mt chips to populate the main bank as I didn't have enough of other brands. The extended bank needs sockets and new chips which I will be purchasing. The 130XE is currently only 64K, but at least it's working now.

Edited by atari8warez
  • Like 2

Share this post


Link to post
Share on other sites

Just waiting on my new MMU arriving, then I will post an update.

 

In the mean time.....

 

Merry Christmas everybody, and may you have a safe, prosperous and Happy New Year.

 

Thanks for all your help!

 

Damian.

Share this post


Link to post
Share on other sites

Shame on Atari for ever producing socketless boards. And no, I don't want to hear about how they needed to save money. I say shame on them.

Share this post


Link to post
Share on other sites

Shame on Atari for ever producing socketless boards. And no, I don't want to hear about how they needed to save money. I say shame on them.

Yeah! But at least it's good practice swapping them out. Now I have a nice board fully socketed, that makes me sleep better at night.....

Share this post


Link to post
Share on other sites

Well thanks for all your help everyone.

 

I am running with the original SALLY, ANTIC and GTIA chips, go figure!? But, replaced overheating Ram, Capacitors, MMU and socketed everything (Ram removed and replaced twice lol).

 

It's all good!

 

.... Now I need a new broken Atari.......

 

Have a fantastic 2015 everyone!!!!!!

 

Damian.

 

post-40814-0-35173800-1420071208_thumb.jpg

post-40814-0-73507700-1420071219_thumb.jpg

  • Like 1

Share this post


Link to post
Share on other sites

@ SwipeCA

 

Well done the journey is a bit like the Avatar i use ( A Long and Windy Road ).

I noticed that in the second picture the red wine must have been used to congratulate yourself on a well completed project.

 

Do you really want an other one ???

 

Happy new year (2015).

 

Well done

 

Ray W

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...