C64 PLA Replacement Project
A few years ago my CBM 64 started showing only 2047 basic bytes free.
Then earlier this year it died completely. It would show a black screen,
and that was it. I figured the PLA chip was broken, so I thought it would
be fun to try to replace that myself with my non-existent soldering skills.
Here's how it turned out.
Screenshot taken on the last day before it finally died.
I desoldered/broke off the large metal shield from the bottom of the board. That was rather messy.
I improvised some temporary standoffs to keep the board steady when turned over.
Marking which pins we need to desolder.
Round one with the solder sucker - missed quite a few.
After a few more rounds with the pump and some solder wick I managed to free every pin apart from the ground pin.
Here's what it looks like from the top.
Note corrosion on pin 18 (/CASRAM).
Finally managed to wick enough solder out of the ground hole to lift out the chip.
Liberated! Some crusty stuff in the vicinity of the corrosion noted earlier. It cleaned right off though.
Chip came out in one part. I appear to have destroyed pin 1. But in fact it is supposed to look this way. It's not connected to anything.
Socket for replacement soldered into place. I slightly damaged the solder mask next to the ground pin trying to get all the solder out.
Replacement is a SuperPLA V3. Just checking the jumper settings.
SuperPLA mounted in the socket. Note the cozy little roof for the bypass capacitator.
IT WORKS!
Michiel Boland
18 March 2017
