One bad SID inside a Commodore 64 makes strange sounds

In this video, we explore an old Commodore 64 that lacks a functional keyboard due to damage. Upon opening it, we discovered a ROM switcher on a small board with an expansion ROM. The machine wasn't working, displaying a blank screen. We pulled out the original ROM from the board and reinserted it directly onto the motherboard to troubleshoot. After this, we used some dongles and cartridges to further test the system.

When we powered it on, the machine came to life, which was a good sign. After checking the system, we found a faulty SID chip, which we decided to replace. Using a working SID with a heat sink, we powered it back up and ran some tests. The machine appeared to be functioning well, but we noticed that the faulty SID affected not only the sound but also the control ports and diagnostic results. We replaced the good SID with the faulty one to demonstrate how a bad SID can cause false test results, particularly with the U28 chip (4066).

Overall, despite initial concerns that the Commodore 64 was beyond repair, we were able to get it working again. The keyboard, however, remains damaged and needs further attention. We will continue testing and experimenting with the machine in future videos. Thank you for joining us on this repair adventure!

Chapters
0:00 Intro
0:23 Hello Mighty Pirates!
1:35 Switching on the C64
2:19 Bad sounds coming out
3:00 Replacing the bad sid with a working one
5:34 Broken SID back on the motherboard again for more testing
7:27 Chip U28 (the 4066) reported as bad, not true!
8:27 Keyboard is not working well too