Atari 600XL Video and Memory Upgrade

Recently purchased this sorry looking Atari 600XL untested with no cables.

Turns out it boots up fine and all the keys work.

The video however is very noisy with what looks like a light blue colour bar scrolling up the screen.

Bugger!. The blue scroll bar was due to a failing PSU. Turns out the ingot was outputting 5.3v!!. Should have realised this was the issue. The display would start off perfect then after a few seconds a buzzing would sound through the TV speaker a the blue scroll bar would pop up.

I’ve therefore binned the old PSU ingot after chopping off the din cable and adapted a switch mode 5v 2.5a PSU.

I also chose to remove capacitor C109 which improved the image slightly.

Now to upgrade that ram

The 600XL has only 16k and this particular example has the dreaded TMS manfactured 4416 ram which is prone to failure so lets get it out and upgrade to 4464 chips providing a total 64k. Wiring diagram as follows

  • U11, U12: Replace 16K DRAM 4416 with 64K DRAM 4464 (64K x 4 bit)
  • U5: Lift leg 3, connect to pad ( A15 )
  • U6: Lift leg 10, connect to pad ( A14 )
  • U16: Lift leg 8, connect to R36
  • R36: Lift leg and connect to U16

Wiring done.