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Deteacher

Did I Just Kill my 1200xl?

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Ok, long story short:

 

I bought a 5200 for cheap (untested) and sure enough, it's not working (black screen.) So, I called Best Electronics and I was told I could swap the CPU, Antic, GTIA and POKEY chips with my 1200xl to test them out. The only chip that seemed to test out ok was the POKEY.

 

So, I put the 1200xl chips back in, put it all back together and when I fired it back up, all I get are garbled graphics. Thinking I fried my 1200xl, I just walked away from it and got a beer to calm myself down.

 

When I went to look at some pics of the motherboards, I noticed that the the POKEY, ANTIC and GTIA chips are upside down. I'm about 99% sure I put one or more chips in the wrong way. I don't want to take it all apart now, so my question is: If I did put any/all chips in the wrong way, did I fry my 1200xl motherboard? Will putting them back in bring her back? I figured I'd ask before I take the whole thing apart again.

 

Thanks in advance for helping this noob out. :(

 

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Ok, long story short:

 

I bought a 5200 for cheap (untested) and sure enough, it's not working (black screen.) So, I called Best Electronics and I was told I could swap the CPU, Antic, GTIA and POKEY chips with my 1200xl to test them out. The only chip that seemed to test out ok was the POKEY.

 

So, I put the 1200xl chips back in, put it all back together and when I fired it back up, all I get are garbled graphics. Thinking I fried my 1200xl, I just walked away from it and got a beer to calm myself down.

 

When I went to look at some pics of the motherboards, I noticed that the the POKEY, ANTIC and GTIA chips are upside down. I'm about 99% sure I put one or more chips in the wrong way. I don't want to take it all apart now, so my question is: If I did put any/all chips in the wrong way, did I fry my 1200xl motherboard? Will putting them back in bring her back? I figured I'd ask before I take the whole thing apart again.

 

Thanks in advance for helping this noob out. :(

 

 

Okay, you probably didn't fry your 1200XL. Take a deep breath and look at each chip again carefully. There's a little dot or half-moon shape on one end of each of the ICs. Make sure that end of the chip is on the same side as the white silk-screened half-moon outline under each socket. Be careful removing and reinserting each chip, take a deep breath and go slowly. It'll probably be fine.

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That’s very relieving to hear! Not gonna mess with it tonight but I’ll attack it again tomorrow. Thank you so much for the quick help! :)

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That’s very relieving to hear! Not gonna mess with it tonight but I’ll attack it again tomorrow. Thank you so much for the quick help! :)

 

You're welcome. For reference, here are some pics I took a couple weeks ago the first time I disassembled my most recent 1200XL. Note the little dots and the silk-screening I mentioned. The big 40-pin IC's:

 

left-to-right, top row: 6502C, GTIA,

left-to-right, bottom row: 6520, ANTIC

post-30400-0-04502600-1506215747_thumb.jpg

 

POKEY:

post-30400-0-60465900-1506216343_thumb.jpg

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Your 1200XL is dead for sure. Pack it up carefully and ship it to me ........... :grin: :grin: :grin:

 

 

Nah, good chances are that everything survived but uh.....you learned a lesson...chips have an orientation :-D

 

DOn't be too bothered about it....even though I am quite experienced in electronics I managed to hook up connectors the wrong way (U1MB !!!!) and amazingly stuff seems to survive more than we expect....but it's definitely not always the case....especially when it keeps powered up for longer times...

 

I remember once I did some hacking in my Atari ST and somehow swapped 12V and 5V......that _did_ surely fry some parts....

Edited by Level42
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Ok, so I got up and opened her up again to see what I did. Turns out, I put everything back in correctly:

 

post-9712-0-16344000-1506257502_thumb.jpg

 

post-9712-0-84878300-1506257515_thumb.jpg

 

post-9712-0-07605500-1506257529_thumb.jpg

 

So, I popped them out, inspected them for bent pins and carefully reseated them. Same result:

 

IMG_4097.MOV

 

In the video, I have my AtariMAX Flash cart inserted. In spite of just the pink bar across the screen, I can hear the "tick tick tick" sound as I move the joystick to scroll through the menu settings. If I take the cart out and power it up, I just get a black screen. So, at the very least, it looks like the Antic and/or GTIA chips are shot. Gonna call Best tomorrow and order those two chips. I'll probably just bite the bullet and order a whole new motherboard for the 5200, rather than continue down this path of swapping chips. :(

Edited by Deteacher

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Deteacher,

That's the first time I've seen a 1200XL with 28 pin EPROMS for the factory OS. Just curious, what's the serial number on your 1200XL. I am speculating that you might have a "very" early 1200XL for it to have EPROMs at U12 and U13. I could be way off. Maybe you or a previous owner tried a different OS, but then returned it to Rev 10 not wanting to reset the W6-9 jumper (reverts back to 24 pin ROMS). Look at the empty pads at W6. Looks like they are filled in at the factory. You might have a "very" early production 1200XL (i.e. the ROMs weren't available yet).

 

If you need a new ANTIC and GTIA, another cheap alternative is to buy a cheap CPU board from a 400 or 800. The ANtIC and GTIA are the same as the one used in the 1200XL. The CPU might or might not be. If it (400/800 CPU board) has four smaller IC's, its the 6502B and won't be compatible, but if it only has one smaller IC (board CO15500), then it has the 6502C (SALLY) and that too is the same as the 1200XL. B&C sells the CO15500 CPU board for $20 and has the ANTIC, GTIA and SALLY that is compatible with the 1200XL. Oh crap, I let that secret out. those won't last long.

Edited by ACML

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If you can hear the tick, tick sounds but no video, the damage might be limited to GTIA only. Since a damaged Antic could affect memory access and/or refresh, interfering with proper operation. So I would swap out the GTIA chip first.

 

One chip that seems unaffected by reversal is the CPU, which I know from personal experience.

 

- Michael

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Deteacher,

That's the first time I've seen a 1200XL with 28 pin EPROMS for the factory OS. Just curious, what's the serial number on your 1200XL. I am speculating that you might have a "very" early 1200XL for it to have EPROMs at U12 and U13. I could be way off. Maybe you or a previous owner tried a different OS, but then returned it to Rev 10 not wanting to reset the W6-9 jumper (reverts back to 24 pin ROMS). Look at the empty pads at W6. Looks like they are filled in at the factory. You might have a "very" early production 1200XL (i.e. the ROMs weren't available yet).

 

If you need a new ANTIC and GTIA, another cheap alternative is to buy a cheap CPU board from a 400 or 800. The ANtIC and GTIA are the same as the one used in the 1200XL. The CPU might or might not be. If it (400/800 CPU board) has four smaller IC's, its the 6502B and won't be compatible, but if it only has one smaller IC (board CO15500), then it has the 6502C (SALLY) and that too is the same as the 1200XL. B&C sells the CO15500 CPU board for $20 and has the ANTIC, GTIA and SALLY that is compatible with the 1200XL. Oh crap, I let that secret out. those won't last long.

 

Serial number is 015947. Not sure if that helps at all. The guy I bought it off from had a ton of stuff from his father's business (he was an electronics repairman. From the looks of it, I'm not sure it ever saw the light of day until I opened it up. When I first hooked it up, the keyboard didn't work, so I opened it up, peeled off the mylar and gave it a good gentle cleaning, which brought the keys back to life.

 

Thank you for the info on the 400/800 chip compatibility. That's great knowledge to have in my back pocket. :)

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If you can hear the tick, tick sounds but no video, the damage might be limited to GTIA only. Since a damaged Antic could affect memory access and/or refresh, interfering with proper operation. So I would swap out the GTIA chip first.

 

One chip that seems unaffected by reversal is the CPU, which I know from personal experience.

 

- Michael

 

I know when I first swapped out the GTIA and Antic chips, I put them in backward. But I must have put the "good" ones back in the right way (although I do remember flipping them around when the good chips didn't seem to work.

 

I'm going to order the GTIA and Antic chips and swap them both out. If it doesn't work after that, I fear I might have done damage to the board itself. Thank you for the insight. :)

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With Antic the Vss and Vcc pins are diagonally opposite which means chips wrong way is wired up in reversed polarity.

 

But there's simple symptoms to know if certain chips are at least partially alive.

 

Graphics onscreen without screen rolling = Antic and GTIA probably OK.

Solid colour screen, rolling like V-hold not correct = Antic probably not OK.

 

Aside from the graphics, Antic also does Ram refresh so a nonworking Antic = nonworking system.

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I know when I first swapped out the GTIA and Antic chips, I put them in backward. But I must have put the "good" ones back in the right way (although I do remember flipping them around when the good chips didn't seem to work.

 

I'm going to order the GTIA and Antic chips and swap them both out. If it doesn't work after that, I fear I might have done damage to the board itself. Thank you for the insight. :)

 

That's very unlikely. If anything, you might have damaged the cheap single-wipe sockets Atari used. Most of them can only be relied upon for a few insertion/removal cycles. Here's what I found restoring one of my 1200XL's a few months ago - check out the wipe (metal contact in the socket) for pin 19:

 

post-30400-0-47722400-1506266864_thumb.jpg

 

I ended up replacing 3 sockets and a bad GTIA to get the machine working. I should note that the machine DID boot with the bad GTIA, but it was erratic - graphical glitches, etc., and eventually would crash. But it *DID* at least start up. If you had a logic probe, you could check for bad or intermittent connections by methodically probing each pin of the machine as it's powered on and referring to a pinout diagram, but since you probably don't

 

... at this point, what I would do is remove each of the main chips, carefully and gently, and take a close look at each socket under magnification. Are any wipes broken off (like my photo above) or are they bent inwards noticeably so they won't make good contact with the pins of the chip? Is there debris in any of them? Etc.

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With Antic the Vss and Vcc pins are diagonally opposite which means chips wrong way is wired up in reversed polarity.

 

But there's simple symptoms to know if certain chips are at least partially alive.

 

Graphics onscreen without screen rolling = Antic and GTIA probably OK.

Solid colour screen, rolling like V-hold not correct = Antic probably not OK.

 

Aside from the graphics, Antic also does Ram refresh so a nonworking Antic = nonworking system.

 

Does that mean I may have possibly cooked the RAM as well, or they just won't work because the Antic is dead? The video I attached shows what the display is doing. Just a solid pink band with some random letters in it. If I leave it on longer, the screen will start displaying all kinds of graphical glitches, letters flashing colors, and other general garbage. The screen doesn't appear to roll, just output garbage graphics.

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That's very unlikely. If anything, you might have damaged the cheap single-wipe sockets Atari used. Most of them can only be relied upon for a few insertion/removal cycles. Here's what I found restoring one of my 1200XL's a few months ago - check out the wipe (metal contact in the socket) for pin 19:

 

attachicon.gifXL_broken_socket.jpg

 

I ended up replacing 3 sockets and a bad GTIA to get the machine working. I should note that the machine DID boot with the bad GTIA, but it was erratic - graphical glitches, etc., and eventually would crash. But it *DID* at least start up. If you had a logic probe, you could check for bad or intermittent connections by methodically probing each pin of the machine as it's powered on and referring to a pinout diagram, but since you probably don't

 

... at this point, what I would do is remove each of the main chips, carefully and gently, and take a close look at each socket under magnification. Are any wipes broken off (like my photo above) or are they bent inwards noticeably so they won't make good contact with the pins of the chip? Is there debris in any of them? Etc.

I took a couple chips out and looked at the socket. While the pic you shared clearly shows a breakage, I'm not seeing anything like that on mine. However, when I zoom in, I see what looks like a lot of crud on the connectors. Thoughts?

 

post-9712-0-65395700-1506269009_thumb.jpg

 

post-9712-0-96393100-1506269025_thumb.jpg

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Don't worry so much about the crud, the act of inserting / reseating the chips will normally clear that off, pin breaks are more important but you don't have any..

 

Its rare but not unheard of that its possible to break the socket legs where they go in to the PCB, I use a cheap USB microscope to check these but it really is very rare (as far as I know)

 

Best of luck with the new chips, hope it all works..

 

Paul.

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Don't feel bad, I admit I did the same thing years ago. I can't remember the chip that got fried, but I just kept swapping chips until it worked.

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Partial failure in GTIA is not rare. My 65XE had no keyboard "tick, tick" sounds but video was perfect. I picked up a pair of nos ANTIC/GTIA chips off eBay for around 15 bucks, still plenty of those around.

 

 

 

Most of them can only be relied upon for a few insertion/removal cycles.

 

Those single wipe sockets are poor. Over time, they tend to lose their springiness and contact between the metal in the socket and the leg of the ic chip fails.

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Serial number is 015947. Not sure if that helps at all. The guy I bought it off from had a ton of stuff from his father's business (he was an electronics repairman. From the looks of it, I'm not sure it ever saw the light of day until I opened it up. When I first hooked it up, the keyboard didn't work, so I opened it up, peeled off the mylar and gave it a good gentle cleaning, which brought the keys back to life.

 

Thank you for the info on the 400/800 chip compatibility. That's great knowledge to have in my back pocket. :)

Ok, but what are the last three digits stamped after that. Those tell the month a year of production. Also, I assume the serial you gave is preceded by an 83S. If there is not three digits stamped after the 015947, then that would indeed be very interesting.

Edited by ACML

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Got chip sockets from the early 1970's, that's nearly 50 years. And they were originally coated with small amounts of a cleaner/dielectric compound. Think Deoxit5 or automotive BulbGrease. They're perfect and "silver polish" shiny. And the chips don't even crinkle when you lift them out.

 

When using stuff like that all you need is a tiny amount, 1 eydropper drop is good for 3 or 4 40-pin ICs.

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Ok, but what are the last three digits stamped after that. Those tell the month a year of production. Also, I assume the serial you gave is preceded by an 83S. If there is not three digits stamped after the 015947, then that would indeed be very interesting.

 

Here's a pic of the back label:

 

post-9712-0-91204800-1506297230_thumb.jpg

 

If this turns out to be some kind or early production model, that will just motivate me that much more to get her up and running again!

Edited by Deteacher
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Got chip sockets from the early 1970's, that's nearly 50 years. And they were originally coated with small amounts of a cleaner/dielectric compound. Think Deoxit5 or automotive BulbGrease. They're perfect and "silver polish" shiny. And the chips don't even crinkle when you lift them out.

 

When using stuff like that all you need is a tiny amount, 1 eydropper drop is good for 3 or 4 40-pin ICs.

 

Yeah, these chips crinkle like a mother when I pull them/reseat them. I have some deoxit at work. I'm going to bring it home and treat them before I put the new chips in.

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