600XL: flickering, video errors

[dfletch]

In a sudden fit of nostalgia I got my 600XL from the attic after 20 years, decided to give it that 64k RAM upgrade, good times.

So I fitted 2 TMM41464AP-10 RAMs and made the modifications to the three other ICs as described in one mod tut found on the web.

 

I noticed that something heavy hit the machine (probably while moving) and the keyboard has a few broken circuit tracks. I fixed this with jumper wires (not pretty but works).

 

Now - the video output behaves erratically: it reverses at random, there is no visible cursor and when I start typing (well, even if I don't sometimes) there is a lot of flickering and groups of characters become inversed and have trailing inverted dots. Can take a screenshot if that helps.

 

Now: does POKEY affect ANTIC? I noticed some tracks running between those.

Could the RAM upgrade lead to the above effects?

Or is the machine simply done for? (Spent two decades unused on attics.)

 

Let's say I did not do a good job in the keyboard, is there any external keyboard one could attach? (Or if some has an otherwisely broken 600XL with intact keyboard I would be interested in buying it.)

 

[dfletch]

Update: Turns out it even produces those flickering errors with the keyboard disconnected. Gets worse when moving the device. Will pluck the main ICs and hose the thing down with WD40. Maybe build a new RF shielding, the original somehow got.. lost.

Edited November 25, 2013 by dfletch

[Rybags]

RF shielding won't really matter... unless somehow it's bent to the point of making contact where it shouldn't.

 

Do you have the text of the upgrade instructions? IIRC there was one set that wasn't quite correct. I did the upgrade myself and had no problems.

 

Trying another CPU and/or Antic might be a good idea if you can. Also, try on monitor port rather than RF - RF jacks can be unreliable as they're not a great design to start with and are made of crappy materials.

 

Screenshot and/or video might give a hint too.

[Panther]

Update: Turns out it even produces those flickering errors with the keyboard disconnected. Gets worse when moving the device. Will pluck the main ICs and hose the thing down with WD40. Maybe build a new RF shielding, the original somehow got.. lost.

 

Might I recommend instead that you use contact cleaner instead of WD40?

You didn't mention, does it boot okay and load programs?

[dfletch]

@Rybags: I followed those: http://atariage.com/forums/topic/183694-600xl-64k-upgrade-pictures/

 

Here are two videos, 4 and 36MB:

http://www.vaultofsages.de/~dexterf/videos/atari600xl_flickeing.m4v

http://www.vaultofsages.de/~dexterf/videos/atari600xl_flickering_long.m4v

[dfletch]

 

Not my finest soldering job but should work. I did not unsolder the R36 leg but cut it and bent up the resistor. Technically should be the same.