Atari 1200XL Club (a rare bunch)

[unsafe357]

Thanks for the quick responses!

 

ACML, this is the power supply I'm using: https://thebrewingacademy.com/products/tbas-replacement-power-supply-for-atari-400-800-1050-xf551-1200xl?_pos=2&_sid=c72af2950&_ss=r  I ran another test and got this result (different):

 

 

To even get to the memory test, I have to reboot like 5-10x before I get the Atari splash screen which allows me to go to the Help test.

 

Interesting take, Ricky Spanish - you think the keyboard could affect the test? I'll try repairing the keyboard before ordering any replacement ram chips in that case.

Edited September 8, 2022 by unsafe357

[+Stephen]

There's nothing in the way of keyboard issues that will cause a ROM or RAM test to show bad.  The keyboard issue is known - the mylar goes bad.

[+kheller2]

It is odd for a 1200XL to behave as such.  Luckily every chip is socketed, 64K ram chips are around and one can flash EPROMs if needed.   Crack it open and reseat all the chips.  

[ACML]

If different blocks of RAM are bad each time you run it, maybe its not the RAM.  There are eight 64Kx1 DRAMs so when you reseat them as kheller2 suggests, you might want to rearrange them so they are in different sockets.  If you still get the same random failures, your issue maybe somewhere else (Memory manager, ANTIC)?  The keyboard is not a contributing factor.  I would think if you had a bad ROM, you'd just get a solid blank screen.  On your first set of photos, it shows one chip failed checksum, but then it worked.  Star Raiders boots.  I'd take kheller2's advice and gently reseat the chips.

Edited September 8, 2022 by ACML

[Muzz73]

I had a 1200XL in the late 1990's, but I donated it to a friend in France (a very serious Atari collector). I had gotten it at a thrift store for $25 USD.

[+x=usr(1536)]

8 hours ago, ACML said:

Star Raiders boots.

For anyone who may not know why this is significant: Star Raiders doesn't use any part of the OS in order to run.  If the machine boots and runs Star Raiders but not other software, there's a possibility that either the OS ROM is bad or an upstream issue is making it appear that way.

8 hours ago, ACML said:

I'd take kheller2's advice and gently reseat the chips.

Absolutely.  Adding to that: since the machine will be open anyway, carefully remove them, hit the legs and sockets with contact cleaner, Deoxit, etc. and see if that makes a difference.

 

@unsafe357: do the results of the RAM / ROM tests change depending on how long the machine has been switched on for, and do they happen in a random or repeatable pattern?  I'm wondering if it may not be a heat issue affecting <insert borderline component here>.

[Mclaneinc]

6 hours ago, Muzz73 said:

I had a 1200XL in the late 1990's, but I donated it to a friend in France (a very serious Atari collector). I had gotten it at a thrift store for $25 USD.

Nice story and great price..I recently joined the 1200 league thanks to some generous thoughts..

 

I wonder if the 8 bit collector is Manu?

[unsafe357]

6 hours ago, x=usr(1536) said:

For anyone who may not know why this is significant: Star Raiders doesn't use any part of the OS in order to run.  If the machine boots and runs Star Raiders but not other software, there's a possibility that either the OS ROM is bad or an upstream issue is making it appear that way.

Absolutely.  Adding to that: since the machine will be open anyway, carefully remove them, hit the legs and sockets with contact cleaner, Deoxit, etc. and see if that makes a difference.

 

@unsafe357: do the results of the RAM / ROM tests change depending on how long the machine has been switched on for, and do they happen in a random or repeatable pattern?  I'm wondering if it may not be a heat issue affecting <insert borderline component here>.

 

Thanks for all the suggestions guys! I'll reseat the chips/clean em' up with contact cleaner while I have it cracked open to do the keyboard repair. Hoping I'll have time to give it a go next week.

 

@x=usr(1536) - The test results to appear to change each time I run the test whether it's cold or been on for awhile. One thing I found odd - when I hit the help key it immediately goes to the memory test. *ONCE* it allowed me into the test menu itself to select a different test if I wanted to. Not sure if this is significant... 

 

Interesting theory on a potential heat issue. Is there anything inside I can apply thermal compound to in order to rule that out?

 

I really appreciate everyone chiming in to help out - I'll let you know the new results once I fix the keyboard and reseat/clean the chips.

 

Thank you!

[Ricky Spanish]

5 minutes ago, unsafe357 said:

I have it cracked open to do the keyboard repair.

Do the keyboard repair first, then try the memory test again if you don't mind. I'm just curious. 

[+x=usr(1536)]

56 minutes ago, unsafe357 said:

The test results to appear to change each time I run the test whether it's cold or been on for awhile. One thing I found odd - when I hit the help key it immediately goes to the memory test. *ONCE* it allowed me into the test menu itself to select a different test if I wanted to. Not sure if this is significant... 

That's interesting.  Definitely sort the keyboard out first; without it working, further testing is going to be seriously complicated.

 

The jump straight to the memory test makes me suspect the possibility of bad RAM, but having the ROM test also flip-flop has me wondering if there aren't multiple issues.

 

Since you've got the machine open, can you take a look at the RAM and let us know the manufacturer?  I suspect it's probably MT-branded, but would like confirmation or denial.  Oh, and a good hi-res photo of the PCB would also be helpful if you could take one.  Also, do the L1 and L2 LEDs flash during the memory test?

 

@ACML brings up a good point re: a possibly-failing ANTIC, but there's also other logic involved in the memory management that might be an issue.  Don't want to point fingers just yet because there's no real reason to, but either one is a possibility.

 

On the plus side, if sound and joysticks are working in Star Raiders, there's a good chance that the POKEY isn't shot which means that your keyboard may come back up with a cleaning on the connector or a new mylar.  Obviously that's not a 100% guarantee, but it at least bodes well for now.

56 minutes ago, unsafe357 said:

Interesting theory on a potential heat issue. Is there anything inside I can apply thermal compound to in order to rule that out?

I should've been clearer about what I meant by heat: it wasn't meant so much to refer to temperatures inside the case (though those could certainly have an effect), but rather the temperatures of individual components.    A failing (or failed) component could be getting hotter than its spec would normally call for, so it's possible for it to flake out under just the right thermal conditions.

 

Having said that, unless the machine has a lot of internally-installed modifications or something that may be blocking airflow and/or heat escape, it should be able to run just fine without thermal compound, heatsinks, fans, etc.  It may be worth touching components (or using a thermal imaging camera, temperature gun, etc. if one is available) to see if any are running way hotter than they should be.  In this case, I'd start with the ICs after the machine has been on for 10 to 15 minutes and go from there.

[unsafe357]

@x=usr(1536) - Absolutely! Once I get the machine open I'll snap some pics to share. I just ordered a conductive silver ink pen and a mini heat gun to do the keyboard mylar fix. Everything should be here by next Wednesday; I think I should be able to work on it next Thursday or Friday.

 

Sound works in Star Raiders but I wasn't able to get the game itself to start (I was able to select difficulty level but that's it). Does the joystick button generally get the game to start? I assumed it wasn't starting because of the keyboard is out. I did hit the joystick button, but nothing happened.

 

I also noticed that the Power LED doesn't constantly stay lit... Do you think the power supply could be suspect or perhaps just a flakey LED? I've gotten stuff from Brewing Academy in the past with no complaints.

 

Thanks again to the forum for taking the time to help me figure this out. Hoping I can get it back up and running soon!

 

 

 

 

 

 

[ACML]

34 minutes ago, unsafe357 said:

I also noticed that the Power LED doesn't constantly stay lit... Do you think the power supply could be suspect or perhaps just a flakey LED?

The intermittent LED is common.  Atari put very little solder on the LEDs inserted in the little green PCB that holds the three LEDs.  Just reheat the solder pad and touch it up with a little more fresh solder and it will be 100% reliable again.

 

[Muzz73]

14 hours ago, Mclaneinc said:

Nice story and great price..I recently joined the 1200 league thanks to some generous thoughts..

 

I wonder if the 8 bit collector is Manu?

Hello!

 

My friend's name is Patrice Mueller. He and his then wife came out to visit the U.S. on vacation a couple of years consecutively in the late 1990's and I let them stay with me for several days. I sent him home with Atari goodies on his first trip:

 

1200XL computer

PS3000 monitor/drive combo

1030 MoDem

XM301 MoDem

520STm computer

 

I filled in a few blanks in his collection, many of which never came out in Europe. He was pretty stoked. 👍

[+x=usr(1536)]

16 hours ago, unsafe357 said:

Sound works in Star Raiders but I wasn't able to get the game itself to start (I was able to select difficulty level but that's it). Does the joystick button generally get the game to start?

Not always, but in some games, yes.  More:

16 hours ago, unsafe357 said:

I assumed it wasn't starting because of the keyboard is out. I did hit the joystick button, but nothing happened.

This is correct - the START, SELECT, OPTION, etc. keys all run through the keyboard mylar so likely aren't working or are only working when they feel like it.  Star Raiders doesn't do the fire-to-start routine that some other games do, however, so everything's as expected in your case

[+mytek]

On 9/7/2022 at 10:41 PM, Muzz73 said:

I had a 1200XL in the late 1990's, but I donated it to a friend in France (a very serious Atari collector). I had gotten it at a thrift store for $25 USD.

Wow those were the days!!!

 

I'm trying to recall the last time I saw anything Atari 8-bit related in a thrift store   I'm thinking maybe around 1997. I do remember picking up a sh_t load of cartridges in a big cardboard box at a local flea market in 1996 for $20. There must have been at least 30 carts in that box, and I believe there was also a set of joysticks and paddles as well. At that same flea market I got a couple of 800XL computers for another $20. I certainly do miss those deals.

[unsafe357]

Good news all! The 1200XL is alive and well. Truth be told, I didn't have the time to diagnose and fix it myself. I met a dude named Paul at PRGE who has a company called EightBitFix,https://www.eightbitfix.com/  (he specializes in fixing Atari 8 bit computers). Here's what he ended up doing to my 1200XL:

 

Keyboard mylar replaced.

Cleaned cartridge port.

Adjusted color pot.

All chips re-seated / New installed.

Cleaned mobo and keyboard.

Restored +5 volts to SIO port.

Did a 1/2 clear pic mod. Video is now cleaner and brighter.

Diagnostics show no errors.

Replaced missing left front rubber foot.

 

If you're short on time (and patience), I highly recommend him! So happy that this 1200 has a new lease on life - this is definitely one of my better estate sale finds over the years.

 

Turns out the CPU was defective. I attached a video of me sucking at Pitfall 2 in case you wanted to see it in action.

 

 

[BillC]

1 hour ago, unsafe357 said:

I met a dude named Paul at PRGE who has a company called EightBitFix,https://www.eightbitfix.com/  (he specializes in fixing Atari 8 bit computers).

Paul Westphal has been a Atariage member for over 10 years.