Troubleshooting a Commodore 64 with a bad SID that makes strange sounds

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In this new Triple Freedom video, they explore an old Commodore 64 with a non-functional keyboard due to damage. Upon opening the machine, they discovered a ROM switcher on a small board with an expansion ROM. The system wasn’t working, displaying only a blank screen. To troubleshoot, they removed the original ROM from the board and reinserted it directly onto the motherboard. They also used various dongles and cartridges to further test the system.

Upon powering it on, the machine came to life. While re-checking the system, they identified a faulty SID chip, which they decided to replace. After installing a working SID with a heat sink, they ran additional tests. The machine seemed to be functioning well, but they observed that the faulty SID affected sound and interfered with the control ports and diagnostic results. To demonstrate this, they swapped the good SID with the faulty one, showing how a bad SID could produce false test results, particularly involving the U28 chip (4066).

Despite initial concerns that the Commodore 64 was beyond repair, they successfully restored it to working condition. However, the damaged keyboard remains an issue and will need further attention. Triple Freedom plans to continue testing and experimenting with the machine in a future video.

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