Commodore PET Repair and Restore
The 8-Bit Guy・14 minutes read
The Commodore PET computer faced cleanliness, screen, and keyboard issues, which were resolved through cleaning, testing, and repairs. Despite challenges in finding schematics and documentation, progress was made in fixing the computer, with remaining issues in reattaching a corner decal and fixing a malfunctioning space bar.
Insights
- Cleaning with baking soda significantly improved the appearance of the Commodore PET, tackling the issue of dirt effectively.
- Troubleshooting the keyboard involved detailed testing of various components like the logic board, decoder chip, and key switches, with successful repairs achieved through meticulous cleaning and repair attempts, leading to a functional keyboard.
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Adjust potentiometers for brightness.
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Summary
00:00
"Reviving Commodore PET: Keyboard Repair Success"
- The Commodore PET has three main issues: dirt, dim screen, and non-functional keyboard.
- Cleaning the computer involved using baking soda to scrub off dirt, resulting in a significant improvement in appearance.
- The keyboard issue was tackled by understanding its wiring and layout, involving a grid system with output and input lines.
- Troubleshooting the keyboard involved testing the logic board, decoder chip, wiring, and key switches.
- A test with alligator clips revealed the logic board was functioning, leading to further tests on the keyboard.
- Disassembling the keyboard revealed no visible issues, prompting a thorough cleaning of the board and carbon contacts.
- Attempts to improve conductivity using de-oxit, a pencil, and a repair kit were made, with mixed results.
- After a 24-hour wait, testing the repaired plungers on the circuit board showed positive results, indicating progress.
- Reassembling the keyboard and testing it outside the computer confirmed its functionality.
- Additional tasks included fixing an EPROM sticker, testing aftermarket software, and adjusting screen brightness using potentiometers.
12:34
Repairing PET Computer Keyboard: Decal and Space Bar
- Schematics for the PET computer are challenging to find due to its limited production and design changes over the years, leading to mismatches with available documentation. Despite this, progress has been made in repairing the computer, with issues remaining in reattaching a corner decal and fixing a malfunctioning space bar due to a broken plastic tab.
- The keyboard of the PET computer faces two main problems: the graphics characters on the keys are scratched off, and the space bar only functions properly when pressed in the center due to a broken plastic tab, which the individual plans to repair using various methods after addressing the decal issue.
