iz8dwf | CBM PET 2001 repair part 1: Cleaning. 5V regulators. 6550 and 6540 @iz8dwf | Uploaded November 2018 | Updated October 2024, 3 hours ago.
Commodore PET 2001-8, S/N 1004791 repair/restoration.
Part 1: cleaning oxide on connectors, after removing the oxide, it didn't seem the tin layer to be exposing any copper, so I decided to not re-tinning the contacts.
Debugging RAM/ROM problems. A good part of MPS6550 resulted faulty after 40 years and one MPS6540 ROM had also failed.
A 7805 regulator just failed in the middle of the repair sessions, but it was sourcing a too large current due to the faulty ROM probably.
Using my own RAM/ROM daughterboard for troubleshooting purposes.
The test program that I use can be found here:
ceffy.de/2001test10.bin
Part 2 video:
youtube.com/watch?v=GIij-oGMjS8
Part 3 video:
youtube.com/watch?v=Io1QiW8KTXA
Commodore PET 2001-8, S/N 1004791 repair/restoration.
Part 1: cleaning oxide on connectors, after removing the oxide, it didn't seem the tin layer to be exposing any copper, so I decided to not re-tinning the contacts.
Debugging RAM/ROM problems. A good part of MPS6550 resulted faulty after 40 years and one MPS6540 ROM had also failed.
A 7805 regulator just failed in the middle of the repair sessions, but it was sourcing a too large current due to the faulty ROM probably.
Using my own RAM/ROM daughterboard for troubleshooting purposes.
The test program that I use can be found here:
ceffy.de/2001test10.bin
Part 2 video:
youtube.com/watch?v=GIij-oGMjS8
Part 3 video:
youtube.com/watch?v=Io1QiW8KTXA
![Servicing Apple ][ and IIe power supplies: change the RIFA capacitors!](https://i.ytimg.com/vi/NpZgDRZhO4c/hqdefault.jpg "Servicing Apple ][ and IIe power supplies: change the RIFA capacitors!
Astec power supply for the Apple ][ (plain, plus, europlus) and IIe 8 bit computers. They employ some X2-rated capacitors made by RIFA. These capacitors always crack and with moisture entering, they short out and release a lot of smoke. Every power supply of this kind must be inspected and the problematic capacitors substituted before attempting to power them on.")
