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Atari 800XL black screen


xXsir_MoneyXx
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Hello

 

I have just bought an atari 800XL and a 1050 from an online seller. The machine is almost pristine (only the metal buttons are a bit scratched) and IT was never modified until now.

When I first set it up I didn't notice any problem (I ran the self test, and it all worked perfectly), however I hadn't got any game to test, so I built an SIO2PC interface myself. Unfortunately, when I booted the atari with the SIO2PC it went straight to the self test, displaying bad memory. I found out the ram chips were branded by MT (i have read MT 4264s fail very often), so I removed the chips, installed sockets (my atari is a PAL machine) and placed new TI 4164s. Luckily it prompted to basic, so I used it the whole afternoon without issues.

Now here's the strange part: when today I powered on my atari again, the screen went brown for a fraction of second, and then it just changed into black!!!

I know there are lots of possible bad chips/electronic components, but I made some tests, and here's what I can say:

 

1) I tested it via RF and via monitor output, and I got the same result

2) I reseated all the socketed chips

3) I tried typing something, but i didn't get any beep

4) I checked the conductivity of the ram sockets

5) I tried booting a game (draconus) from disk, but the disk didn't even spindle

6) I checked the electrolytic capacitors, and they appeared to be OK

7) I checked the output of the PSU (it's a british one, part CO61763-34) and it displayed 4.7/4.8V, and inside the machine i got 5.18/5.22V (I think i got 4.7V because the PSU is designed for 240V AC input, but here in Italy we have 220V).

 

I think the atari isn't responsive at all (no commands from the SIO port, no audio...), the only thing I get is the brown screen when i boot it up.

 

This is frustrating! What can i do? May the CPU be bad? Sorry for my english, it's my first topic.

 

Thanks in advance :)

 

P.S.: Sadly I don't have any cartridge or spare part to test. The only atari microcomputer-related thing I have is the 800XL, a 1050 and a 1010

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Try this: http://atari.boards.net/thread/893/black-screen-problems-fix-checklist

 

Your "brown" screen might actually be a "red" screen issue, since there's no video upgrade and stock machines' red's can often look brown.

From my experience, red (or brown) screens usually means memory issues, while black can mean that but also more than that.

 

Make sure your ram ship sockets are not loose or "wiggly." very recently I had to replace a bad socket for my U1 ram chip, I'd get the black/red screens when turning it on.

Edited by Gunstar
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I went through a five week ordeal in the late spring/summer of this year repairing and restoring one of my 1200XL's. Turns out the machine had three bad sockets and a failed GTIA. But the initial failure to boot past the red/brown screen was the CPU socket; a failed CPU would give similar symptoms. That's the first thing I'd check, followed by ANTIC.

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Brown then black is at least a positive sign, should mean the CPU is OK, the OS Rom and MMU should be OK as well.

 

Usually if you get that transition there should be a pop through the TV speaker as the colour changes. If the machine hangs then try pushing Reset and listen for another pop.

 

For a machine that gets to this point and no further though - could be one of multiple things like bad Ram, bad Basic Rom or even a partial or intermittent fault of MMU, PIA or OS.

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Well, I just resoldered and double checked EVERY socket pin (I used my tester in continuity mode), but it hasn't solved the problem. I turned the volume at the maximum level, and I heared three pops during startup: one when I switch on the atari, one when the brown/red color changes into black and one after 0.5 seconds after the second pop.

 

Unfortunately i don't have any atari spare part, so it seems I have to order a new SALLY and a new ANTIC online (I thought atari put an entire computer inside a 1050 drive, like Commodore did, but I read it didn't, right?)

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When I first set it up I didn't notice any problem (I ran the self test, and it all worked perfectly), however I hadn't got any game to test, so I built an SIO2PC interface myself. Unfortunately, when I booted the atari with the SIO2PC it went straight to the self test, displaying bad memory.

 

Interesting coincidence. Any chance your homemade effort blew something? Also is the PSU a European version of the infamous ingot supply?

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You get the colour change and pops which means the CPU is probably good.

 

A non rolling screen means that Antic is at least doing it's part for video generation.

 

If you have a diag mode cartridge like Asteroids or Star Raiders then try that. Or try any cartridge which might work if the Basic's bad but nothing else is wrong.

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Well, I found a Star Raiders cartridge online for about 15/18 euros, so I think I'll buy it.

 

From what I have read and watched in this forum, my PSU isn't the ingot one, however I think mine has been refurbished, because I can see some residue that seems super glue. Also, I followed the schematic from Nick Kennedy (using a MAX232CPE) for my SIO2PC interface, it worked just fine for an entire day (and I turned the atari on and off several times!). I can't understand how the interface could damage the computer after a day of intensive usage...

 

Here are some photos of my PSU:

post-62897-0-12123200-1513533388_thumb.jpeg

post-62897-0-96759500-1513533407_thumb.jpeg

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I've seen this a dozen times with Galaga arcade PCBs and NAMCO custom chips.

 

Some of the older TI ICs were silver plated, the silver plate oxidises over time and peels off leaving the base metal exposed. It's also likely that the leads short out as the plate peels off. I would replace those chips.

Edited by shoestring
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If you find any solution, please post it. I have a similar issue with an 800XL, but I get a blue screen. Total blue, no border, no sound, no clicks to indicate an effort to boot. The only indication of life is response to adjusting the color pot. I have also changed every socketed chip and I am in the process of socketing the chips that aren't.

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Did you feel around for any chips getting hot ?

 

With all respect but I can't understand why anyone would still build a SIO2PC today ? I mean I did this too in the late 90s but quite recently I removed it from my 130XE because I own one of these now: http://lotharek.pl/product.php?pid=98

 

Not only can you use it on more than one machine (which is my biggest reason for getting an external solution) but it also allows higher transfer speeds and can be connector to USB.....

 

On a side note: already since several decades the voltages are officially agreed to be 230VAC across Europe. The U.K. Went down a bit, and we on the mainland went up. I just measured 231 VAC today. Of course, with the margins, and depending on how far you are from your local transformer it can be higher or lower...

 

However, using a 220V supply will still work, output voltage will be a little higher but almost all power supply designs will have enough margin to handle it. Using a 240VAC will put a little less stress on your devices.....in fact, when I still had arcade machines o always rewired the transformers from the 220VAC tab to the 240VAC tab whenever possible (was always possible with Atari machines).

 

About the RAM chips....did you fully insert them into the sockets? . I had the same kind of things happen when I had put sockets on a 130XE board and replaced all RAM. Only when I pressed really pretty hard on all the RAMs some would "snap" into position and this fixed the issue.

I saw you checked continuity on your sockets but did you check continuity "end to end" so from the top of the RAM pins to the solder side of the PCB ?

 

Sometimes there are still bad socket connections on the bigger chips.....I've seen that twice now. Sometimes it helps to power up the board (totally removed it from the case) and gently trying to "warp" (bend) the PCB in two diagonal corners. This sometimes reveals those contact issues as the board jumps to live when bent in a certain position.

Last board I worked on started working again when I pushed the ANTIC on the "front"side towards the backside of the PCB.... replaced socket and problem fixed...

 

By the way your power supply is this one:

http://atariage.com/forums/topic/221488-euro-power-supplies/?p=2917490

 

It's not the European version of the "Ingot" so no worries there. It's not my favorite either because you can't repair it but I have had no problems with the one I do have and never heard that they are problematic.

Edited by Level42
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It might be ideal to try an acquire a cheap known working 600xl or 800xl that you can substitute chips to.

 

Custom chips are somewhat difficult to troubleshoot due to their complexity. Rather than just substitute parts into a dead machine until it works, I think it's easier to substitute parts from a dead or partially dead machine into a known working machine until the fault is reproduced. It will also tell you if the faults lie somewhere else. I know this method isn't very scientific but it's quick and easy.

 

 

I was also wondering if there's a way to test the OS and BASIC roms...

 

I use an EEtools TopMAX universal programmer to test them out of circuit, they're not cheap but there may be cheaper options out there that can read 2364 and 27128 EPROMs.

 

I dump the mask rom if it's readable and compare against known good CRCs in the list below.

 

http://www.wudsn.com/productions/atari800/atariromchecker/help/AtariROMChecker.html

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  • 2 months later...

Today I was working on an 800XL that booted to a red screen for about one second. The screen would then go black. There was usually one "boot click" when the power was turned on. By successively replacing chips,I found that the XL delay chip was the culprit. I forgot the U number, it is the chip that is missing several legs. I was replacing from bad machine to good machine as previously suggested.

Edited by hueyjones70
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Also working in a 600xl with sometimes red screen, black screen, or goes directly to memory test. On top of that, when it worked, it has a greenish colors, so the ready blue screen of basic the best you can get was aqua, when playing with the color pot.

I also had some ICs with that dark color in the feet. I cleaned everything with contact cleaner and changed one socket I found suspicious. Last week I found that the 40th pin of Sally was not making contact, because of the faulty socket.

Now I am waiting for new 40pin sockets.

I tested most of the chips in a partially socketed Taiwanese 800XL , but the ones I suspected the most: PIA and MMU are not socketed in the 800XL. Can I just piggyback them to test them?

 

What I recommend given my limited experience repairing Atari, is to check "continuity" between the shoulder of the pin and some point in the PCB which is different than the pin itself.

That way you can find broken sockets or soldering points.

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What I recommend given my limited experience repairing Atari, is to check "continuity" between the shoulder of the pin and some point in the PCB which is different than the pin itself.

That way you can find broken sockets or soldering points.

 

That's excellent advice. With my 1200XL, one socket wipe was broken off completely due to corrosion. That was pretty obvious when checking continuity (note pin 19).

 

post-30400-0-02275900-1520092640_thumb.jpg

 

After fixing that, I found lack of continuity for one pin each on POKEY and PIA. Resocketing all three (plus replacing a bad GTIA) ultimately fixed the machine. But it was a damn lot of work tracking down all these separate issues. Hard to imagine what this poor machine had been put through before I ended up with it.

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I read here that ram chips can be tested putting a working one on top. Which other ICs are safe and can be tested that way?

What about the way around?:

Working machine, and you piggyback a bad chip. The machine keep working.. So the chip is good? Or no conclusion?

Or machine stop working so just messed up, or two let's say PIAs cannot work in parallel..?

Anyone had investigated those cases?

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I am going to make a suggestion I have not noticed as a mention in all of the A A threads....

 

I was taught to ALWAYS push chips in before wiggling and moving them out, and also to try to pull them straight up (or a little at a time from each side), this usually requires an 'arcane' chip puller.

 

the swipes may be corroded, the plastic may be brittle. The corrosion forms a not so conductive but mechanical bond, you will break the swiped and the plastic sometimes. Pushing them in first gently breaks the bond, slight wiggle and pulling straight up clears the corrosion and friction while preserving the plastic that can no longer handle the torsion applied by uneven twisting from leveraging chips up one side at a time. This is devastating to old swipes, sockets, and sometimes even the legs on certain chips.

 

Please consider what I share with you, and then de oxit the swipes and legs during cleaning and re-insertion..

Edited by _The Doctor__
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I read here that ram chips can be tested putting a working one on top. Which other ICs are safe and can be tested that way?

What about the way around?:

Working machine, and you piggyback a bad chip. The machine keep working.. So the chip is good? Or no conclusion?

Or machine stop working so just messed up, or two let's say PIAs cannot work in parallel..?

Anyone had investigated those cases?

 

 

 

It is a quick test you can do for TTLs and some DRAMs/SRAMs. But if the chip is shorted internally then the piggy back test is rather pointless.

 

Other chips such as custom chips, ASICs, CPUs..etc are more complex and this method isn't recommended.

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Hey, I finally got out of these awful busy months, and I decided to socket and replace all the chips in the middle of the board, except for the delay chip. They are pretty cheap, although the shipping price is a pain in the wallet (about 25$ from Mouser).

I think I would probably check the continuity and substitute the 40 pin sockets, because there is no evident damage on them. Hope I'll figure out the cause of this curse!

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  • 2 weeks later...

Black screen or blue screen I have an 800XL that has previously been a blank blue screen and is now a blank black screen. I have changed every chip on the MB and they all work on another computer. I don't know if this is the problem or not but, the GTIA pins 12, 13, and 14 ( these are for START, SELECT, AND OPTION) only show .1 to .15 Volts. I have checked the voltage on the pins and on the connectors in the back of the MB. I get the same voltage at both ends of R133, R134, and R135; likewise on pins 20, 21, and 22 on the keyboard connector. I can't trace where the voltage comes from. Does anyone know. I have tried 3 different GTIA chips on the bad board and none of them work but they all work on a different computer.

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