Museum Report 6-27-2013
- Today being a wednesday it was quiet. We had one family of visitors with their two teenage girls.
I finally got to swap out the keyboard controller on the Apple-1 Mimeo, it was "freaking" out after being left on for a while.
I also brought my scope and started working on the Cassette Interface on the Sol-20. Looks like the PLL chip was bad and I was able to perform the calibration. Next fault was traced to a bad UART, so I swapped them both out using my spares I brought, figure if one is bad the other may not be trustworthy. These were my last two personal spares, so I'll have to track down more. After the swap out, I was able to catalog a tape (iPod wave file) and start to try loading software from my iPod. This failed, though it was able to read the program name header and length. I swapped out the memory card just to double check and finally put the scope across the big caps in the power supply. There is a lot of noise/ripple, so it looks like we will be needing two caps. When I got home I did compare to my working Sol-20 which has NOS caps in the supply and my caps are clean and my cassette interface works, so I'm hoping my suspicion that the noise is messing up the circuit works out. There is another Sol-20 at the museum that I didn't even try powering on, next week I'll bring the scope and my ESR meter and check it's caps and then swap them with the "mostly" working system. Worst case I'll have to order some big caps, they just aren't super cheap.
Evan also showed up around 4:30 for an InfoAge meeting that night and helped me read one of my paper tapes on the ASR-33 I made with my punch at home. I think I may have a sticking bit that works fine in papertape, but with mylar tape it may be leaving hanging chads that don't always punch through, I needed a print out to compare to the results of my newly hooked up highspeed tape reader. Worst case time for some maintenance on the punch.
That about covers it,