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alortegac

Atari 800 XL black screen

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6 hours ago, cwilbar said:

If your Rams are MT, one is very likely bad.

 

From the picture he posted, they are not mtRAMS... but I would replace all of them anyway since they are all socketed.

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I will keep you posted once they arrive. 

on a little off topic side note, my 130xe’s video convergence is way off. Especially the blue layer. Could that be my composite video cable or is it something else. I tested on a crt monitor, and lcd monitor, and a tv and it’s bad on all of them. 

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sound like a cable issue, you've answered your own question...

also consider the XE has signals on the video jack that an unmodified 800XL does not...

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1 hour ago, sideburn said:

I will keep you posted once they arrive. 

on a little off topic side note, my 130xe’s video convergence is way off. Especially the blue layer. Could that be my composite video cable or is it something else. I tested on a crt monitor, and lcd monitor, and a tv and it’s bad on all of them. 

This is a reputable seller. Good quality cables. Above link to cable with S-Video For your 130Xe. You need to have a monitor or tv with S-video input.
 
This other cable is good for your 800xl. Composite input in your tv or monitor. Your 130xe will also work with this cable, composite only.  
 
 
Have you tried testing your computer with the rf cable?  If your screen display correctly, then you know it is something wrong with the cable or composite circuit (socket, cold joint or a capacitor) 
 
 
Edited by alortegac

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20 minutes ago, alortegac said:
This is a reputable seller. Good quality cables. Above link to cable with S-Video For your 130Xe. You need to have a monitor or tv with S-video input.
 
This other cable is good for your 800xl. Composite input in your tv or monitor. Your 130xe will also work with this cable, composite only.  
 
 
Have you tried testing your computer with the rf cable?  If your screen display correctly, then you know it is something wrong with the cable or composite circuit (socket, cold joint or a capacitor) 
 
 


I ordered that exact xe cable from them yesterday. 
 

I have not tried RF. Good idea, I will try that next. 

 

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OK I got that RAM and this was weird.

I swapped all 8 out and no change, black screen.

I then swapped the only socketed chip I had in mu 130XE, the GTIA and no change..

 

I then try powering up again and boom its working!

 

So I'm not sure if maybe the metal shield on the bottom was shifted and shorting something or what but it's working now.

 

I then swapped the original rams one chip at a time and found two bad rams.

 

The only issue now is the self test pages start going bonkers on the display but they are working properly. Only the display starts jittering around like crazy.

Everything else works perfectly, I put my UNO cart in and ran a bunch of games and demos and they all work fine.

 

So I am not sure why the Self Test screen is whacky...

 

 

IMG_1250.jpeg

IMG_1249.jpeg

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OK the plot thickens... All the sudden it got really bad and powers up straight into self test and the screen is going nuts...

I take the whole thing apart again, remove the metal shield of the top and the bottom and set the board down on the workbench, power it up and its working flawlessly... self test page is nice and clean and passing all tests.. What gives! when i pu the thing back together it goes whacko on me..

 

Tempted to not put the damn shield on. what a PITA!

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None of my machines have the shields anymore. Possibility for display noise, but I've never seen a difference on mine.

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3 minutes ago, chevymad said:

None of my machines have the shields anymore. Possibility for display noise, but I've never seen a difference on mine.

I think I got it. I think the shield thing was just a coincidence. I re-seated the ROMs and so far so good. Time will tell…

 

I’d ditch the shields but this one is brand new. Rather keep it in mint / stock condition. 

Edited by sideburn
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I have never heard of shields causing issues unless there is damage/misalignment/or missing insulation... I almost all case shielding is a plus over time.

 

What you describe sounds like a combination of some bad ram and chips not making great contact in sockets... I suggest pushing down on chips a few times and maybe some deoxit, Sometimes the sockets go bad. Always push the chip down in couple place before pulling chips to avoid damage as some swipes may be slightly oxidized and bonded to the chip legs... Most of the time pushing down, deoxit while pulling and reseating is all that is needed along with replacing the few bad ram chips in the machines.

 

Also consider checking the electrolytic caps near the power switch etc...

 

Sockets for chips can go bad... it happens. Not often but often enough.

 

Edited by _The Doctor__
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That’s what I did. I think I’m good to go. Looks like it might have been a bad connection with the rom and a couple bad ram chips. 
 

thanks for the help everyone. 

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5 hours ago, sideburn said:

I think I got it. I think the shield thing was just a coincidence. I re-seated the ROMs and so far so good. Time will tell…

 

I’d ditch the shields but this one is brand new. Rather keep it in mint / stock condition. 

Almost sure the problem was the bad ram. The rest of the issues are probably just due to moving things around, pulling chips, etc. It only takes one pin on one of the sockets to cause all the strange behavior. 

it can be also be a cold joint somewhere.

 

Happy it is working now,  as suggested above, you can spray deoxit on the sockets. You may not want to remove the chips again, but spray it with them on and let it dry. 


@ _The Doctor_ is the real expert here, he has helped me several times and I learned a lot from him….hats off! 


Good job! Enjoy your machines!

 

btw, are you still having the issue of the blue color on the 130xe?

 

 

 

 

Edited by alortegac

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1 hour ago, alortegac said:

Almost sure the problem was the bad ram. The rest of the issues are probably just due to moving things around, pulling chips, etc. It only takes one pin on one of the sockets to cause all the strange behavior. 

it can be also be a cold joint somewhere.

 

Happy it is working now,  as suggested above, you can spray deoxit on the sockets. You may not want to remove the chips again, but spray it with them on and let it dry. 


@ _The Doctor_ is the real expert here, he has helped me several times and I learned a lot from him….hats off! 


Good job! Enjoy your machines!

 

btw, are you still having the issue of the blue color on the 130xe?

 

 

 

 


I agree. I bet it was only the ram. Yeah, I may pull it back apart and spray all the sockets. I’ve already got plenty of Deoxit. I love that stuff! I should have thought of that when I was re-seating all the chips. 
 

Yes, still issues with the 130xe convergence but it’s looking the 800xl video is about the same so I’m leaning towards it being the cable. I hooked RF to the 800xl and it looked much better. Still need to try that on the 130xe. 
 

Still got two more machines to fix. An Amiga 2000 that I don’t know what the heck happened to it, but it had major issues. Bad ram, blown Agnus and CIA chips, corroded battery & leakage, and more.  I’ve finally got that working except for the hard drive. The disk activates and then solid HD activity LED. 

 

A Vectrex with a board that suffered bad corrosion. It’s now got a clock but that’s about it. 
 

Also an Apple ][ plus with bad ram that I just fixed. 
 

All of these have been in storage for a few years. In the same location. It’s interesting that all of them have / had bad ram and were all in working order before I boxed them up back then… 

 

I should probably get rid of a bunch of this stuff so I’ll have fewer broken things to fix every day and be forced to get some real work done! 😂 

 

*The Ataris ain’t goin nowhere though. I still have all my floppies and programs from when I was 13 for those puppies. 

Edited by sideburn

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12 hours ago, sideburn said:

OK the plot thickens... All the sudden it got really bad and powers up straight into self test and the screen is going nuts...

I take the whole thing apart again, remove the metal shield of the top and the bottom and set the board down on the workbench, power it up and its working flawlessly... self test page is nice and clean and passing all tests.. What gives! when i pu the thing back together it goes whacko on me..

 

Tempted to not put the damn shield on. what a PITA!

 

I had a real problem with the shield in one 800XL I was working on.  If the sides of your metal shield can move around (not affixed to the top of the shield at the front of the shield, then the right side can move inward a bit and short against resistors that are there.

 

You can put some electrical tape around the bottom front of the right side of the shield to stop this problem.

 

It does sound like same issue I had, and if so, it is at least an easy fix.

 

I have run into one other 800XL that used the same shield construction, but on that one the sides were soldered on the inside near the top front to keep the sides from moving and hitting components due to the flexibility of the sides with that shield design.

 

 

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the shield is normally tightened with it aligned to the front of the Atari, if any pcb mask is damaged you can put fresh on the pcb or tape like was mentioned. the back side an 800XL normally has some protection at the PBI  port.. nothing a piece of electrical tape or masking tape didn't take care of back there... I prefer Kapton/polymide tape though.

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1 hour ago, cwilbar said:

 

I had a real problem with the shield in one 800XL I was working on.  If the sides of your metal shield can move around (not affixed to the top of the shield at the front of the shield, then the right side can move inward a bit and short against resistors that are there.

 

You can put some electrical tape around the bottom front of the right side of the shield to stop this problem.

 

It does sound like same issue I had, and if so, it is at least an easy fix.

 

I have run into one other 800XL that used the same shield construction, but on that one the sides were soldered on the inside near the top front to keep the sides from moving and hitting components due to the flexibility of the sides with that shield design.

 

 

I have a feeling that might have been what happened after I replaced the ram and it still wasn’t working. I had the bottom sheiks under the board just loose. 

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28 minutes ago, _The Doctor__ said:

the shield is normally tightened with it aligned to the front of the Atari, if any pcb mask is damaged you can put fresh on the pcb or tape like was mentioned. the back side an 800XL normally has some protection at the PBI  port.. nothing a piece of electrical tape or masking tape didn't take care of back there... I prefer Kapton/polymide tape though.

Yeah kapton would be best for that I think. If it starts acting up again I’ll take it apart again, inspect the shielding, kapton insulate, and Deoxit the sockets. I’ve always been using my 130xe and left this 800xl in the box since it’s it such NOS condition but now I think I’m going to start using it instead. I forgot how much nicer they are. 

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1 hour ago, _The Doctor__ said:

the shield is normally tightened with it aligned to the front of the Atari, if any pcb mask is damaged you can put fresh on the pcb or tape like was mentioned. the back side an 800XL normally has some protection at the PBI  port.. nothing a piece of electrical tape or masking tape didn't take care of back there... I prefer Kapton/polymide tape though.

I've seen two different types of shields.  The problematic one is the one I described, the seam between the top and right hand side is 'cut' in the formation of the shield.  In one case there was a solder point on the inside connecting the top towards the front which makes the shield more rigid.  In my other, there was nothing to make the shield rigid and act as one piece.  The shield can be flexed on the right very little and permit the shield to touch the resistors on the inside of the right side of the shield.  It was not the shield touching traces/etc, just it being slightly flexed in at the right and touching those resistors that are just inside the shield.  A bit of tape on the inside of the right edge of the shield will keep it from shorting out on those resistors.  Better yet if you have a high watt soldering iron is to solder the shield together near the front of the shield on top which will make it rigid and it won't touch the resistors.

 

When I had this problem on that 800XL, it was almost dumb luck that I found what was happening. 

 

 

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So the good news: The new cable got here today and it is 1,000 times better. Now the picture is how I remember it being.

 

And the bad news: Today is also the day the 800xl decided to start acting up again... goes directly into self test and the screen is bonkers (but looks much better with the new cable! lol)... Time to get the Deoxit out...

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Well I Deoxited every chip on the board. The problem is totally random. comes and goes so I don't think it is the shield (its off for now until I sort it out) nor a bad connection. it has a life of its own so I think its a bad chip. I need to get some canned air and freeze the chips and see if that affects anything.

 

** I found another clue... if I let a test run for a while like the memory test, the flickering gets worse and worse over time like the sprites are flying all over the place on the screen and then when i force the screen to redraw by returning to the main menu it draws the screen perfectly and then starts messing up again. This might explain why games are working ok because the screen is redrawing a lot.

Edited by sideburn

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@sideburn  It could be one of the new RAM chips have gone bad again/is starting to fail.

 

When you experience the onscreen glitches have you carefully pressed down on the main 40pin ICs (CPU, ANTIC, GTIA), perhaps 4050, delay line, MMU and RAM chips one at a time in turn with the power on?  I once found a weakness relating to an Antic IC socket by observing the reaction of doing so. Also are all the IC's pins definitely sitting in their socket recesses, (eg none bent albeit still engaging)?

 

It could also be a less than perfect solder connection between a socket pin(s) and the via(s) on the PCB that as the board heats up and expands under certain ICs, (eg like Antic), causes weak connection.

 

Also all the RAM chips replaced, are they all the same NS rating? 

 

Just throwing some things out here. :D

Edited by Beeblebrox

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32 minutes ago, Beeblebrox said:

@sideburn  It could be one of the new RAM chips have gone bad again/is starting to fail.

 

When you experience the onscreen glitches have you carefully pressed down on the main 40pin ICs (CPU, ANTIC, GTIA), perhaps 4050, delay line, MMU and RAM chips one at a time in turn with the power on?  I once found a weakness relating to an Antic IC socket by observing the reaction of doing so. Also are all the IC's pins definitely sitting in their socket recesses, (eg none bent albeit still engaging)?

 

It could also be a less than perfect solder connection between a socket pin(s) and the via(s) on the PCB that as the board heats up and expands under certain ICs, (eg like Antic), causes weak connection.

 

Also all the RAM chips replaced, are they all the same NS rating? 

 

Just throwing some things out here. :D

I dont think its the Ram the ram tests are passing while the screen is going bonkers and i swapped out the new ram with the old and back.

Yeah I reseated the chips many times and inspected the board. Its clean. New... 

 

I found an old 800xl in storage maybe the chips are socketed.. Sometimes when i power up it goes straight into the ram test.

When it powers up my Atarimax and unocart work flawlessly.

 

The only failures are the self test pages go whacky on the screen and it occasionally booting directly into the self test. if it doesn't it works perfectly consistently.

 

 

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17 minutes ago, sideburn said:

I dont think its the Ram the ram tests are passing while the screen is going bonkers and i swapped out the new ram with the old and back.

Yeah I reseated the chips many times and inspected the board. Its clean. New... 

 

I found an old 800xl in storage maybe the chips are socketed.. Sometimes when i power up it goes straight into the ram test.

When it powers up my Atarimax and unocart work flawlessly.

 

The only failures are the self test pages go whacky on the screen and it occasionally booting directly into the self test. if it doesn't it works perfectly consistently.

 

 

@sideburn  Sure, perhaps rule out RAM issues then. What I was mainly trying to suggest is a perhaps systematic checking for weak connections from the socket(s) themselves to their connection to the PCB whilst it is on. That way to can see any reactions when pressing down on each IC. The Antic issue I had you couldn't see looking at it, and continuity checked out both sides of the board for it's socket - but it turned out to be a single bad connection between the socket's pin and the PCB.

 

 

 

 

Edited by Beeblebrox

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the fact it's going to the self test indicates it's a detectable fault, move the ram chips around and try again, pay careful attention, if any bar is not green. OS rom / Basic / Ram

 And then do  the pokey music test... if nothing shows, you may have a PIA / Glue chip failing. Freeze spray can help identify it (aka aero duster etc , upside down)

let it warm to failure, then spray them one at a time and test while the machine is still hot and the single chip is frozen... do over and over till you find the marginal chip.

Edited by _The Doctor__

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If you would like to try this, it worked for me on a C64 that was having intermittent issues like your machine…….…I  used my IC straightener tool (or very flat pair of pliers) to get the pins well aligned and straighten out. Then I bent the pins a bit inwards to make them go really tight into the socket.  I did one at a time and then test. Make sure all pins go into the socket….a misplaced IC can cause issues too. 

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