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Atari 800 XL black screen


alortegac
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54 minutes ago, alortegac said:

 

Check your av cable, test the computer with an rf cable and in a different tv. Rule out any connections issue.

 

Testing your power supply. It should +5v. Electrolytic capacitors are old now, maybe dry or shorted. 

 

If all good, now it is time for measuring voltages. Check for 5v. Start with The on/off switch.  Check all electrolytic capacitors, one could be shorted.  

if all ok, Then “re-seat” all the chips in their socket. Push them down gently but firmly in place.


Then let it run for some time, “feel” the chips, check if any is really hot, specially RAM chips. 
 

if you still haven’t found any issues,  it is time to pull your logic probe, voltmeter and sam’s. 
 

Black screen is a common failure, but can be caused by many things. Sometimes, multiple things. 
 

it would help if you have another 800xl, testing one chip at time in a known working machine. Some of the chips in the 130xl are compatible, but they may not all be socketed. 

it is important only doing one thing at the time and observe any changes.

 

Hopefully, this is helpful. I have now fixed 30 or 40 machines, they are all repairable, don’t give up. 
 

If you would like me to repair it for you at no charge only parts, Send me a pm. 
 

 

Best!

Al

 

 

 


I can try RF but since composite is displaying / sending a black picture and I have no sound it sure looks like the os is the issue. 
 

+5 off usb, confirmed working from a 139xe. 
 

I thought maybe the caps as well so unopened the computer up and the entire board looks like it just came off the manufacturing floor. Caps look brand new. 
 

yeah I did most everything you suggested. 
I opened it up. Inspected the board, reseated some chips but not all because this thing is mint and the chips are seated in there solid! I did pull a few out and reseated them. I swapped the cpu since that’s all I have as a spare.  
 

I hooked my oscilloscope up and checked every chip and I see data. 
 

None of the chips are getting hot. 
 

the only thing I can thing if that’s left to try is putting a logic probe on the chips but I don’t know what to look for. 
 

unless there’s chips I can use off my 130 xe to test with, I do not have a spare 800xl unfortunately. 

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Posted (edited)

Attached 130xe and 800xl. sams. Check the parts list and compare them. Main chips are the same,  and that you can test.

 

capacitors may look ok visually, but may be shorted (dryed) or with high esr. Not all leak before failing. Look for shorts with your multimeter in continuity  mode.

 


 

 

130XE - Sams ComputerFacts.pdf Atari_800XL_Sams_Computerfacts_Technical_Service.pdf

Edited by alortegac
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9 minutes ago, alortegac said:

Attached 130xe and 800xl. sams. Check the parts list and compare them. Main chips are the same,  and that you can test.

 

capacitors may look ok visually, but may be shorted (dryed) or with high esr. Not all leak before failing. Look for shorts with your multimeter in continuity  mode.

 


 

 

130XE - Sams ComputerFacts.pdf 6.9 MB · 2 downloads Atari_800XL_Sams_Computerfacts_Technical_Service.pdf 14.87 MB · 1 download


Thanks, I will compare parts. I assume the xe chips are not socketed so I’ll have to desolder and socket them. Bad caps become shorted?

 

Can I swap the ROMs between the two machines?

 

if this machine ever took a hit from a bad PSU do you know what commonly fails as a result?

 

 

Edited by sideburn
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Posted (edited)

I would not recommend disoldering the good chips in the 130xe. It is tricky and you may unintentionally lift traces. It can become quite a can of worms. Too much heat can also damage your good working chips. 

 

Yes, bad caps can become open or short. Or simply don’t work as intended anymore, but not always preventing the computer from starting.  Check them with multimeter in continuity mode. You shouldn’t get a solid beep if it is not short. Also, you would notice voltage dropping in the circuit. 
 

A shorted diode can also cause black screen. You can check them

with your multimeter too. 

In general, I would start by checking voltages, all IC’s at 5v on the vcc leg.

 

If you have extra ram chips, I would just replace them. Ram is very prone to failure as someone else already mentioned.

 

4164 ics are the correct ram.

https://twistywristarcade.com/
 

 

 

 

 

 


 

Edited by alortegac
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@sideburn  Not had time to read all the thread in detail so just skim read it, but number one cause is highly likely one or more bad ram chips causing the black screen.  MMU (C061618) is worth checkng, then Bad CPU, Antic and OS rom next.  Delay line chip also.

 

My money is on one or more bad ram chips.

 

The SAMS guides linked earlier have troubleshooting guides. RAM is relatively cheap.

 

I use my excellent Sys Check II module most of the time to ascertain which chips are bad. 

 

It could be a number of other things and there is chance if you could resolve one thing another will be revealed. I've had this happen countless times and have been sent down rabbit holes mant times.

 

If you have the skills then worth socketing all the ram IMHO. I do this with most of my A8s initially.

 

You can swap a good number of chips between an XE and 800XL. I've done this many times with my 65XE which I use when fixing other A8s. Both machines have the same OS ROM chip yes.

 

BTW do you know if you have a stock 800XL or one with the Freddie chip (an XLF)?

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A socketed machine is a huge plus especially if it's the ram, on the C64 it's pretty much a must as they are blighted by MIT rams which are awful. Of course, not a job for a soldering beginner, as mentioned earlier, these old machines can lift traces with unsettling ease if any force or too much heat is used. The last thing you want is a machine full of bodge wires, looks awful, and says to a buyer that it wasn't treated well.

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1 hour ago, Beeblebrox said:

@sideburn  Not had time to read all the thread in detail so just skim read it, but number one cause is highly likely one or more bad ram chips causing the black screen.  MMU (C061618) is worth checkng, then Bad CPU, Antic and OS rom next.  Delay line chip also.

 

My money is on one or more bad ram chips.

 

The SAMS guides linked earlier have troubleshooting guides. RAM is relatively cheap.

 

I use my excellent Sys Check II module most of the time to ascertain which chips are bad. 

 

It could be a number of other things and there is chance if you could resolve one thing another will be revealed. I've had this happen countless times and have been sent down rabbit holes mant times.

 

If you have the skills then worth socketing all the ram IMHO. I do this with most of my A8s initially.

 

You can swap a good number of chips between an XE and 800XL. I've done this many times with my 65XE which I use when fixing other A8s. Both machines have the same OS ROM chip yes.

 

BTW do you know if you have a stock 800XL or one with the Freddie chip (an XLF)?

Hopefully he ram on my XE is socketed. All ram on 800xl is socketed. Does the 800xl need all the ram or can I pull 4 out and see if it boots?

 

I have an Apple ][ as well, can I use that ram by chance? 

 

 Not sure if I have the Freddy version. I uploaded a pic of the board. 
 

7E5D1990-061D-46A3-B72A-7808C058459E.jpeg

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37 minutes ago, Mclaneinc said:

 

A socketed machine is a huge plus especially if it's the ram, on the C64 it's pretty much a must as they are blighted by MIT rams which are awful. Of course, not a job for a soldering beginner, as mentioned earlier, these old machines can lift traces with unsettling ease if any force or too much heat is used. The last thing you want is a machine full of bodge wires, looks awful, and says to a buyer that it wasn't treated well.

I hear ya on the pads lifting and bodge wires. I am also repairing a vectrex and it was bodge wire city all day yesterday! This board is nasty corroded and impossible to not lift traces. 
 

But aside from that, usually there’s not a problem, I have a hacko desoldering gun, heat gun, flux, wick, etc. been soldering since I was a kid in the 80’s but I certainly do not have Louis Rossman surgery skills ? 
 

For ram donor boards I have 130xe, commodore sx-64, apple ][ plus with ram expansion cards, Amiga A1000, and Amiga 2000. I don’t know if my xe has socketed ram or not. The others do. I’ll have to open the xe up and have a look. 

Edited by sideburn
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I don't have stuff like the Hakko gear, just cheapo Aliexpress gear, but I'm not a repair guy except to my own stuff, so a Hakko would be overkill for the work it would get used for. If I win the lottery, then maybe I'll upgrade :)

 

Always wished I'd got a Vectrex back then, silly prices now..

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@sideburn   Well good news - your board is socketed.:D Flip over the casing and on the underside the label should state made in Hong Kong.

 

This makes it a whole lot easier.

 

FYI yours is a standard 800XL with a delay line (eg no Freddie chip).

 

Anyways you'll be best off sourcing the 16-pin 4164 Dram mentioned by Alortegac earlier. Get either 120ns (12n) or 150ns (15n) RAM. Make sure it's 64Kx1Bit.

 

Incidentally what Apple Drams do you have? Pop the chip number/details here and maybe it'll be compatible. 

 

 

for example: https://www.ebay.co.uk/itm/334004379230

 

EDIT: I realise quickly reading a few of the earlier posts just now you obviusly are aware this is socketed. (The last few posts talked about soldering so I'd naturally assumed is wasn't a socketed board until now.)

Anyways  - I'd definitely invest in some new DRAM, whip out the current ones and replace them all and hopefully that'll sort it. You can always keep the old ones as spares.

 

I highly recommend getting a Sys Check II btw.

 

 

Edited by Beeblebrox
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57 minutes ago, sideburn said:

I don’t know if my xe has socketed ram or not.

 

 

I'm betting not. I've never owned an XE machine, but from what I've read here on AA, almost no XEs are socketed. Maybe none of them were. If you wind up having socketed RAM on your XE, chances are it was done by a previous owner, not the factory.

 

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1 hour ago, Mclaneinc said:

I don't have stuff like the Hakko gear, just cheapo Aliexpress gear, but I'm not a repair guy except to my own stuff, so a Hakko would be overkill for the work it would get used for. If I win the lottery, then maybe I'll upgrade :)

 

Always wished I'd got a Vectrex back then, silly prices now..

I know. It was hard to justify buying the hacko but after 30+ years getting angry at those damn spring loaded suckers I just folded and bought one and I have to say, when you DO need to desolder something it’s awesome!

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1 hour ago, Beeblebrox said:

@sideburn   Well good news - your board is socketed.:D Flip over the casing and on the underside the label should state made in Hong Kong.

 

This makes it a whole lot easier.

 

FYI yours is a standard 800XL with a delay line (eg no Freddie chip).

 

Anyways you'll be best off sourcing the 16-pin 4164 Dram mentioned by Alortegac earlier. Get either 120ns (12n) or 150ns (15n) RAM. Make sure it's 64Kx1Bit.

 

Incidentally what Apple Drams do you have? Pop the chip number/details here and maybe it'll be compatible. 

 

 

for example: https://www.ebay.co.uk/itm/334004379230

 

EDIT: I realise quickly reading a few of the earlier posts just now you obviusly are aware this is socketed. (The last few posts talked about soldering so I'd naturally assumed is wasn't a socketed board until now.)

Anyways  - I'd definitely invest in some new DRAM, whip out the current ones and replace them all and hopefully that'll sort it. You can always keep the old ones as spares.

 

I highly recommend getting a Sys Check II btw.

 

 

Yea I noticed the Hong Kong label when I had it apart. Do you know if my 130xe has socketed ram? Or do I have to open it up to find out. 
 

apple rams are TMM414D-3
 

I’ll look at that syscheck. 

Edited by sideburn
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Posted (edited)
1 hour ago, sideburn said:

Hopefully he ram on my XE is socketed. All ram on 800xl is socketed. Does the 800xl need all the ram or can I pull 4 out and see if it boots?

 

I have an Apple ][ as well, can I use that ram by chance? 

 

 Not sure if I have the Freddy version. I uploaded a pic of the board. 
 

7E5D1990-061D-46A3-B72A-7808C058459E.jpeg

I would Just buy a set of new ram chips from the website I shared (reputable seller). It is worth the gamble. 
 

 I wouldn’t  mess with the 130xe. Most XE boards aren’t socketed. De-soldering good IC’s for testing sake is unnecessary and risky. It may cost you much more in the end.

 

Edited by alortegac
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1 minute ago, alortegac said:

I would Just buy a set of new ram chips from the website I shared (reputable seller). It is worth the gamble. 
 

 I wouldn’t  mess with the 130xe. XE boards are never socketed. De-soldering good IC’s for testing sake is unnecessary and risky. It may cost you much more in the end.

 

Ok cool. Yeah I don’t want to mess with it. It’s the only working atari I have 

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3 minutes ago, alortegac said:

I would Just buy a set of new ram chips from the website I shared (reputable seller). It is worth the gamble. 
 

 I wouldn’t  mess with the 130xe. XE boards are never socketed. De-soldering good IC’s for testing sake is unnecessary and risky. It may cost you much more in the end.

 

I edited my post: apple rams are TMM416D-3

Edited by sideburn
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22 minutes ago, alortegac said:

I would Just buy a set of new ram chips from the website I shared (reputable seller). It is worth the gamble. 
 

 I wouldn’t  mess with the 130xe. Most XE boards aren’t socketed. De-soldering good IC’s for testing sake is unnecessary and risky. It may cost you much more in the end.

 

Ok I just ordered 8 of these--> https://twistywristarcade.com/ram/47-4164-ram.html

 

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@sideburn Yup as mentioned by others I think all XEs were not socketed from the factory. I've fully socketed 2 x XEs in the last 12months as part of the fixing process, (long story in each case), and they aren't the most robust Pcbs. XL motherboards are far more hardy and generally better built. Good move buying the new ram chips. Hope it works out. ?

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19 hours ago, sideburn said:

I edited my post: apple rams are TMM416D-3

I believe this is 16K DRAM (common # 4116).  It is not compatible with the 800XL.

 

If your Rams are MT, one is very likely bad.  They are 64x1, data line is pin #2.  If you have a logic probe, try powering on the Atari and check pin  2 on each DRAM.  If one of them is stuck low or stuck high, then the chip could be dead (other things can cause this too but often it is the RAM).  64x1 is still easy to get (4164).

 

If you find a bad one and your XE has socketed RAM (doubtful), and it is 4164 or 4264 (or equivalent 64k x 1 chip), then you can borrow one to try in the XL.  But I would not take a soldering iron to a working XE, it isn't worth it considering all the chips are still available and it is not worth it to mess with it.

 

 

 

 

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2 hours ago, cwilbar said:

I believe this is 16K DRAM (common # 4116).  It is not compatible with the 800XL.

 

If your Rams are MT, one is very likely bad.  They are 64x1, data line is pin #2.  If you have a logic probe, try powering on the Atari and check pin  2 on each DRAM.  If one of them is stuck low or stuck high, then the chip could be dead (other things can cause this too but often it is the RAM).  64x1 is still easy to get (4164).

 

If you find a bad one and your XE has socketed RAM (doubtful), and it is 4164 or 4264 (or equivalent 64k x 1 chip), then you can borrow one to try in the XL.  But I would not take a soldering iron to a working XE, it isn't worth it considering all the chips are still available and it is not worth it to mess with it.

 

 

 

 

Oh no I ordered them  already. Crap. 
 

oh you mean the apple ram. 

Edited by sideburn
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@sideburn  Yup I think Cwilbar was referring to the Apple ram you had originally mentioned as being incompatible. You are fine with the current order of DRAMs with have placed. Just replace all of the current Drams with the new ones. Such good luck you have a socketed board. :)  Worth noting that on occasion in the new DRAMS you have ordered, you might get a dud. It's happened to me before.

 

I have a little cheap to buy but quality DRAM tester unit which is fantastic and I highly recommend it (there the DRAM ALWAYS goes in the right hand socket - (if it goes in the left it'll get fried!!!:-o):

Dynamic RAM (DRAM) Tester 4027/4096/4116/4516/4816/4532/3732/4164/4128/41256/etc

https://www.ebay.co.uk/itm/124726020732

image.thumb.png.c04d7348c5d09dd5d14ab3fc1b536986.png

 

Incidentally looking at the photo of your 800XL's MB the current Ram chips are not MT brand. I don't know much about the brand/model of chip you have. 

Edited by Beeblebrox
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