1200XL (0 for 3) (video & no keyboards func)

[Grand_National]

I dusted off my old Atari 1200XL from college (from 32 years ago) and to my surprise I found 2 others which I must have picked up somewhere along the way.  Unfortunately, none work. 

 

I've looked through the 1200XL field service manual, but it doesn't seem to help me much.

 

The first one (lets call it, "#1"), gives a diagonal multi-colored moving striped screen.  I'm using a home-built composite cable which is known to work.  I use it on my 800XL (and the other (2) 1200XLs) without issue (I have another thread about its assembly).  The LED lights up when turned on and  I can read Atari (probably the scrolling mult-colored Atari logo at boot-up when no cartridge is in the 1200XL.  None of the keys seem to work though, not self-test, or even reset.  I'm at a loss for what the issue could be.

 

The second and third ones ("#2","#3") have identical keyboard symptoms as above, but the machines seem to boot fine.  I get a blue screen with the audio buzz (since no peripherals are connected) and then the scrolling multi-colored Atari logo due to no cartridge.  The LEDs are on.  The problem is no keys work, not even the function keys or even reset.  ALL keys are dead.  I can't even do a self-test, b/c I no keys work at startup.  I opened one of the keyboards and the mylar looks brand new (no oxidation, peeling, cracking, etc.) and besides the function keys don't work which is separate from the std querty keyboard.  I'm at a loss.

 

Any and all feedback is welcome.

 

 

[mimo]

1200xls are notorious for keyboard issues. I have managed to fix a couple by removing the "fingers" on the connection after carefully peeling up the mylar

Excellent video from @flashjazzcat

 

 

For the other one , first gently pry up the chips from their sockets and reseat them, if that doesn't work try swapping the chips from the bad one to the working one and see which one stops it from working, start with the CPU then the ram 

[+DrVenkman]

The diagonal scrolling mess might well be a bad GTIA - without seeing pics, your description sounds like the CPU and ANTIC are trying to produce a pic but the TV isn’t getting a good signal. Try removing and reseating the GTIA to see if it helps. If not, swap the GTIA from that machine into one of you others and see if the symptoms “follow the chip” from the bad video machine to the next one. 

 

The keyboard fix is pretty much a necessity for a 1200XL after decades. I’ve done two of my own machines with this classic (tedious!) repair:

 

http://retrobits.net/atari/keyboard.shtml

 

Disassembly the keyboard, removing the Mylar and then reassembling it all is far more time-consuming than the repair itself. I used Bare conductive carbon ink, painted on with a very fine art brush. 5 years after I did the fixes, both keyboards still work fine.

[+bob1200xl]

You need to replace C115 and L15 with wire to fix #1. You might as well replace R63 with a wire and remove C60 while you're at it. (C60 is about an inch to the left of C115)

 

The keyboards need to be fixed as has been explained.

 

Bob

 

[+CharlieChaplin]

My interpretation of "1200XL (0 for 3) (video and no keyboard func)" was...

 

1200XL (0 Dollars for 3), because no video and no keyboard function.  ?

 

[Grand_National]

I'm not sure exactly what you mean.  I meant that out of 3, none worked.   I did pay something for these decades ago, but you're right, I won't get top dollar for them since none work 100%.  The parts may be worth something, but the goal is to get one (or as many as possible) working, not sell them, at least not yet. 

 

Here's a "blast from the past" (see pics).  How many of you remember seeing these? -- notice the brand-name they were sold under.  Maybe, just maybe, I can get one of these kbds working.  If not, then new mylar.

[Grand_National]

I always thought this was strange because they contained no spec sheet at all (not even voltage or pinouts, let alone a key mapping).  The hobbyist back in the day would have needed to decipher this on their own.