There is a lot of good advice on the forum about fixing 130XE's with broken memories. When mine failed I found all the information I needed here and here, but there are many other good posts too. Thanks to everyone who has posted on this topic. I'm not very experienced with hardware, and there is no way I could have repaired my machine without your guidance.
Just for the record, here's a description of the fault and repair in pictures:
The machine starting booting to the ROM/RAM test.
![130xe Ram failure]( "130xe Ram failure")
Case opened, showing the 16 RAM chips on the left hand side.
![Case Opened]( "Case Opened")
Original chips. One is an NEC 4164, but the other fifteen are the notorious MT 4264's.
![130xe original Ram]( "130xe original Ram")
Chips removed by snipping the pins, withdrawing them one at a time with a soldering iron and tweezers, and finally clearing the holes with a solder sucker.
![130xe Ram removed]( "130xe Ram removed")
Sockets soldered in place and new chips installed. I chose 41256's to give me the easy option to upgrade the machine to 320K in future.
![130xe New Ram]( "130xe New Ram")
Fixed!
![Fixed]( "Fixed")
I still have one question on my mind. Opinions vary on whether it is necessary to tie the unused address line (A8, pin 1) on the 41256's to ground (or possibly I have misinterpreted the opinions). I have not done this yet, but the machine has run perfectly well for days on end. This seems to imply that the chips respond in a predictable manner to disconnected address lines. Can anyone confirm if this is the case?
Just for the record, here's a description of the fault and repair in pictures:
The machine starting booting to the ROM/RAM test.
Case opened, showing the 16 RAM chips on the left hand side.
Original chips. One is an NEC 4164, but the other fifteen are the notorious MT 4264's.
Chips removed by snipping the pins, withdrawing them one at a time with a soldering iron and tweezers, and finally clearing the holes with a solder sucker.
Sockets soldered in place and new chips installed. I chose 41256's to give me the easy option to upgrade the machine to 320K in future.
Fixed!
I still have one question on my mind. Opinions vary on whether it is necessary to tie the unused address line (A8, pin 1) on the 41256's to ground (or possibly I have misinterpreted the opinions). I have not done this yet, but the machine has run perfectly well for days on end. This seems to imply that the chips respond in a predictable manner to disconnected address lines. Can anyone confirm if this is the case?