Atari 1200XL powers up - No LED or keyboard activity present...

[flashjazzcat]

Here's the whole procedure from start to finish:

 

[+kheller2]

it's tedious but is indeed absolutely needed to make sure that tape stuff is out of there, just be super careful doing it... and by all means make sure the conductive stuff is mixed up really well... bleed through makes it appear as though it was a little thin... this is a game of mils.... so clean with a good build up is key

 

if it doesn't get the job done after that , one last coating of the fingers right up to the white might be in order....

Doc is right in about those fingers. I repaired a prototype1200XL once and that keyboard was a bear to separate the mylar from the PCB without total enilation. I had to create new fingers and made sure they connected to the existing traces on the mylar. A multimeter showed me that one still wasn making contact. After that was fixed it worked perfectly.

 

YMMV and of course a new best mylar is the easiest way to go. Not much if anything else goes wrong on those 1200s. Jumper the 5v line to the proper SIO pin and you are good to go.

[_The Doctor__]

as a read the thread I didn't any hint that making sure the whole thing was warm enough to help the adhesive leave go when pulling up the mylar... FJC's video is a good thing to watch also... as he posted it above, I highly suggest getting to the good part and watching it. Very practical!

Edited August 10, 2018 by _The Doctor__

[flashjazzcat]

You don't have to wait too long. I start heating the board about five minutes in.

[NISMOPC]

Congrats on your new 1200XL! They are really beautiful. Use it for a few days and it'll grow even more on you and when you go back to the 800XL it will seem small.

 

Interestingly, my reason for getting this one was to complete my XL line (600XL, 800XL, 1200XL - US releases), but was not wanting to spend the kind of money people were asking. This was a bit more than I wanted to spend, but took a chance on ebay (sold as is - untested) with a buy it now and am pleased with the results so far even with the mylar issue.

 

My main unit is a 600XL with DIN Video mod and 512k ram expansion due to the size and top loader. I prefer smaller units, but absolutely LOVE this 1200XL now that it's in my possession.

Edited August 10, 2018 by NISMOPC

[NISMOPC]

UPDATE: IT WORKS!!!

 

Even though I ordered the Best Electronics mylar, I took advice to get the original mylar working. After several patient attempts slowly with heat gun on low heat to remove the mylar from the PCB (and the white insulator layer), several parts of the insulator would not come off easily and the mylar pretty much was useless once I removed it. I had to scrape off several parts of the keyboard PCB where the insulator basically adhered to the PCB.

 

So, on to the Best Electronics mylar. It took me 4 attempts to get it working properly. On the 4th attempt I finally decided to place a small piece of insulated electrical tape between the case and the mylar connection to increase the compression where the mylar connection to the PCB was. IT WORKED.

 

Should be the last time I open this 1200XL. I plan to keep this one with my CIB "stock" collection of 8-bits.

 

Finally...

 

Edited August 20, 2018 by NISMOPC