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Atari 800 XL black screen


Meall
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Hi There,

 

I have a friend who is selling an Atari 800XL with a 1050 disk drive. The main problem preventing me from buying is that he says when the computer is turned on, it will show a black screen.

 

I wonder what it could be, and how much it can cost to repair. Anyone can share their thought?

 

Thank you

 

Edit: I forgot to mention, but I saw another guy selling an 130XE with disk drive fully working. But when I read on the forum, I see that people do not like it very much even if it has more memory than the 800XL...

Edited by Meall
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too many possibilities

ram, OS Rom, Basic Rom, MMU, PIA

 

start with the easiest stuff - have a look at the board and identify what of the above are socketed - as you can swap these for known good chips and may help you sort it cheaply.

 

where are you based? i have some spare ram/IC chips for an XL

or failing that, i also have a stock good XL

 

btw- 130XE is a good machine, aesthetically, it's a little boring, but a fine 8-bit nonetheless

Edited by Guest
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We really need some sort of troubleshooting sticky so every computer failure doesn't result in a new topic.

 

 

While I agree a sticky would be good, AtariAge is primarily a forum. It's on the order of 15 years old or more now. Not many brand new things talk about day after day for most people. Unless Al wants to exclude all but those building or developing new hardware/software, that's kind of the nature of the beast.

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too many possibilities

ram, OS Rom, Basic Rom, MMU, PIA

 

start with the easiest stuff - have a look at the board and identify what of the above are socketed - as you can swap these for known good chips and may help you sort it cheaply.

 

where are you based? i have some spare ram/IC chips for an XL

or failing that, i also have a stock good XL

 

btw- 130XE is a good machine, aesthetically, it's a little boring, but a fine 8-bit nonetheless

 

 

I am in Quebec, Canada, probably not local to you!

 

The guy selling it told me the previous owner did a first check on the machine and determine that the chips under the keyboard were ok. What does that mean exactly, I'm not sure...

 

As for the 130XE, I mostly read that the keyboard is awful for someone who wants to type a lot on it, like doing programming. But I guess for gaming it is good enough.

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We really need some sort of troubleshooting sticky so every computer failure doesn't result in a new topic.

 

Sorry, my intent was not to annoy anyone. I did a quick search, but could not find an answer for it. That said, I probably agree that we should have an iFixIt type of reference for every old computer, as they all need repairs (or will) and each brand has its own things...

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Sorry, my intent was not to annoy anyone. I did a quick search, but could not find an answer for it. That said, I probably agree that we should have an iFixIt type of reference for every old computer, as they all need repairs (or will) and each brand has its own things...

 

No worries, I'm not annoyed. It's just that the same discussions play out over and over again when someone gets their hands on something that doesn't work and it would be far more helpful to have the responses in one place so people can find them.

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I am in Quebec, Canada, probably not local to you!

 

The guy selling it told me the previous owner did a first check on the machine and determine that the chips under the keyboard were ok. What does that mean exactly, I'm not sure...

 

As for the 130XE, I mostly read that the keyboard is awful for someone who wants to type a lot on it, like doing programming. But I guess for gaming it is good enough.

 

if he was sure it was working then i'd look at the following:

post-10165-0-16951100-1361817996.jpg

 

1] if the board is socketed, rather than soldered you may have some "unseated" ICs.

look at the picture above (from previous AAge thread) and check to see if

ram, OS Rom, Antic, MMU, PIA (even CPU also) are fully in their sockets.

they can look "seated" but may not be. if your comfortable with doing so, you can remove them and reinsert.

 

2] if still a black screen try this (turn TV volume up):

power up using OPTION key, wait five seconds, press SELECT key once, press START

do you hear the musical notes? if so your computer is working

now press HELP, then SELECT, the START

press different keys randomly....do you hear the keyboard BEEPS?

these are good signs that your atari is fundamentally ok.

 

3] power supply may be a problem - it may not be supplying 5v. you'll need to try another PSU.

 

4] are you using RF/monitor output?

if RF, do you have a little channel switch next to the RF output lead? try repeatedly moving it back and forth - it can get dirt inside and cause bad contact.

try a monitor cable - these are fairly standard these days and are monitor to scart/RCA/S-video cables

 

5] try booting with a cartridge in the slot -

Star Raiders cart runs a diag on Antic, CPU and GTIA - so if Star Raiders works then ALL three should be good

which narrows your fault down to PIA, OS Rom, MMU or Ram

5] leave machine on for ten minutes....are any ram chips "overheating"?

 

there's some stuff to try there...good luck

Edited by Guest
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Open it up and remove the RF shield. Turn it on for a minute and see which chips get hot. This is a good start. Hopefully it is socketed. Get replacement chips at Best Electronics. Check my power supply pics at www.eightbitfix.com. Identify which one you have, toss the poop one ( if you have it ) and start with a OK to GREAT one.

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OK, considering your comments, I think I'll take it. He is selling it $80 with the 1050, that sounds not too bad. And no shipping, since he is local to me...

 

brenski: based on the diagram you posted, if the previous owner tested the chips under the keyboard OK, that means the custom chips (Pokey, Antic, etc.) are good. Great news.

 

Paul: he told me previously that it is a socketed one. So it should be easily repairable. I'll look into the PSU when I get it and get back to you to make sure it won't be one that fries the computer before doing too many tests.

 

I do not think he have any games (carts or disk) nor he have joysticks and accessories. He told me that all the cables are included for the disk drive and computer.

 

It will be my first experience with an Atari 8bit, hopefully, it will be a great one.

Edited by Meall
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Open it up and remove the RF shield. Turn it on for a minute and see which chips get hot. This is a good start. Hopefully it is socketed. Get replacement chips at Best Electronics. Check my power supply pics at www.eightbitfix.com. Identify which one you have, toss the poop one ( if you have it ) and start with a OK to GREAT one.

Paul look at the PSU of my 800XL. Based on the picture on your website, maybe that's one of the good one. Let me know. Otherwise, the computer is in pristine condition conditions. Almost like new. Same for the 1050 drive.

post-46830-0-18070500-1467590113_thumb.jpg

post-46830-0-97313600-1467590128_thumb.jpeg

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Paul look at the PSU of my 800XL. Based on the picture on your website, maybe that's one of the good one. Let me know. Otherwise, the computer is in pristine condition conditions. Almost like new. Same for the 1050 drive.

 

Your PS is fine, not the 'ingot'.

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Second best. It's a keeper.

 

Thank you Paul (and russg)

 

I was somewhat evident at first, as the PSU in the picture on Paul's web site all the PSU there looked as baby toy PSU while this one is sure to look as something solid. Still nice to have confirmation from you guys.

 

Paul: you mentioned previously to remove the cover of the RF modulator. Do you mean that bad chips could be in the modulator or this will prevent the some heat from the modulator to be transferred falsely to other chips on the main board?

 

I'll look at further investigation tonight.

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Forget my question about the RF question. I have it open now, and I see it clearly! You were not talking about the RF modulator to connect to the TV, like I said, but the RF shield, my bad! Once open I was expecting to find a motherboard only, like in modern computer, but now I clearly see the shielding! :)

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First investigation, like suggested buy Paul, I turn it on for a few minutes and felt the heat on each chips gave me this result (naming based on the board photo above):

 

- GTIA, PIA stays cool

- Antic, Sally, Pokey are a hot

- basic ROM rev 2 on my board is also hot

- the MMU (on my board it shows part number CO61618) is hot

- a chip with reference CO60462-D is also becoming hot. That chip is strangely socketed in a one-out-of-two pins in its socket. It look strange to me, but maybe normal, just unusual!

 

Every other chips are cool, even cold.

 

But when I compare with the picture above, there are two extra wire connecting together something close from the basic chip to the Pokey. Is it a mod or something, I can't tell...

 

Thank you for helping!

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First investigation, like suggested buy Paul, I turn it on for a few minutes and felt the heat on each chips gave me this result (naming based on the board photo above):

 

- GTIA, PIA stays cool

- Antic, Sally, Pokey are a hot

- basic ROM rev 2 on my board is also hot

- the MMU (on my board it shows part number CO61618) is hot

- a chip with reference CO60462-D is also becoming hot. That chip is strangely socketed in a one-out-of-two pins in its socket. It look strange to me, but maybe normal, just unusual!

 

Every other chips are cool, even cold.

 

But when I compare with the picture above, there are two extra wire connecting together something close from the basic chip to the Pokey. Is it a mod or something, I can't tell...

 

Thank you for helping!

 

which I also suggested a while ago.

did you try any of the other things i suggested? - those numbered 1-5

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if he was sure it was working then i'd look at the following:

My friend told me the previous owner tested the chips under the keyboard, according to his memory. But the 800Xl was not working by itself, black screen, exactly like what I'm seeing.

 

1] if the board is socketed, rather than soldered you may have some "unseated" ICs.

look at the picture above (from previous AAge thread) and check to see if

ram, OS Rom, Antic, MMU, PIA (even CPU also) are fully in their sockets.

they can look "seated" but may not be. if your comfortable with doing so, you can remove them and reinsert.

I looked closely at each chips and they looked very well seated. I removed most of the chips from their sockets (except the 4-5 between the MMU section and the RAM), cleaned the pins, look at the socket itself to see if anything looked broken, but nothing really looked wrong.

 

2] if still a black screen try this (turn TV volume up):

power up using OPTION key, wait five seconds, press SELECT key once, press START

do you hear the musical notes? if so your computer is working

now press HELP, then SELECT, the START

press different keys randomly....do you hear the keyboard BEEPS?

these are good signs that your atari is fundamentally ok.

I tried that, but no sounds or anything that would prove it is reacting to commands I could not see on the screen.

 

3] power supply may be a problem - it may not be supplying 5v. you'll need to try another PSU.

I've been trying to find out the pinouts of the PSU to test it, but was unlucky so far. Can you refer me a site with the correct outputs of each pin?

 

4] are you using RF/monitor output?

Yes

 

if RF, do you have a little channel switch next to the RF output lead? try repeatedly moving it back and forth - it can get dirt inside and cause bad contact.

Tried that too, and no help. I tried also the TV on channel 2 and 3, same result. black screen, only thing I can see is the most right side of the TV is slightly flickering (lighter vertical bar 1 inch wide shaking a bit).

 

try a monitor cable - these are fairly standard these days and are monitor to scart/RCA/S-video cables

I have a cable like this, with two RCA output (Yellow/Video, White/mono sound), but I'm not sure if it is the correct pin out for the Atari. I also tested the cable on a TI99/4a, same result, but again, that's another machine I'm not sure is working.

 

That said, when connected to the Atari, I still have a black screen, and I can hear a buz coming out of the TV speakers. Not sure if it is a signal coming from the computer sound chip, but to me it sounds like an interference, maybe RF frequency.

 

5] try booting with a cartridge in the slot -

I do not have any carts (yet)...

 

5] leave machine on for ten minutes....are any ram chips "overheating"?

Sorry I forgot to mention your name in addition to Paul for suggesting this test. But RAM is not overheating, other chips are...

Edited by Meall
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Those wires next to pokey are stock. Replace the CPU and GTIA first, then ANTIC, PIA. CHeck the ram chips too.

 

 

I have only that one 800XL, so no spare parts...

 

it means you thing I should order all of these and check test them?

 

I will try to make contact with the person who sold it to my friend, hoping I can learn more of what/how he tested and was OK. Because I think the specialized (pokey, sally, etc.) chips have already been tested and were OK.

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brenski, on 03 Jul 2016 - 04:48 AM, said:snapback.png

3] power supply may be a problem - it may not be supplying 5v. you'll need to try another PSU.

 

I finally found the pinout from this thread on the forums:

 

http://atariage.com/forums/topic/184792-800xl-power-supply-connector/

 

From what I can tell, the PSU is working fine.

 

Pins 3,5,7 are connected together as ground, and all pins 1,4,6 are reporting a steady 5.1V.

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I think your best bet is to watch ebay for a junky looking machine that goes cheap for parts. All 600XL's I've seen were socketed and they contain the same chips (except for the RAM). IIRC the XE's are never socketed. As long as the machine doesn't do anything, it's a crap shoot which chip is bad. I don't think I've ever seen a Pokey get even warm.

 

Completed 600XL that went for $20+shipping:

http://www.ebay.com/itm/Atari-600-Xl-Untested-or-for-Parts-/112013257013

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If you consistently get a black screen or initial reddish brown that changes to black then it should mean the CPU, OS and MMU are at least OK.

Chances are the problem is with the Ram.

 

Pokey getting warm... I think it does to an extent given that there's some behaviours that vary by an extra cycle once it's been on for a while.

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