Follow up to this Post: https://lemmy.blahaj.zone/post/8771226
As promised yesterday, here is a look inside the machine! Before it also had spiders and spider webs inside but I cleaned those out!
Beside the dust, one very interesting thing I've found inside on the board are 2 seemingly modded chips with labels on them! The left one read "Ex Basic 2 | Sockel: Mitte | UD4" (Sockel: Mitte is german for Socket: Middle) And the right one just says "Ex Basic | Re 1"
On the back of the machine there is another Ex Basic related Label that says "Ex Basic=sys37100" I wonder what this is all about.
Gonna take an electric Bike pump and see if its powerful enough to get rid of the dust on Saturday, then its time to boot her up for the first proper time!
If there's a voltage regulator in there, make sure that it doesn't suffer from the same problem as later computers from CBM did. If it does, it will fry the board.
Do you happen to know what kind of issues they are and how to recognise them ahead of time?
In Commodore 64 there is a short circuit in the voltage regulator (9V to 5V) after +20 years that sends more than 5V into the 5V line on the system board. Effectively getting one or more essential chips and the computer becomes a desk ornament and a memory from forgotten times.
I would disconnect the power from the system board, connect power and measure the voltage with a multimeter. Might sound like a lot of work but it can be the difference between a working vintage experience and a dead vintage experience.
I had a look at the pictures and the capacitors look fine. There is a known problem with "swollen capacitors". Old things didn't work like they used to. If they are not cylindrical and do not have a flat top they might need to be replaced.
I'm not saying you have to do all this work, I'm just saying that these two things are known problems in some vintage computers.
I've never heard of a PET power supply having the same problems as the notoriously bad C64 power supply, but testing it is probably a good idea anyway, given how electrolytic capacitors can misbehave after long-term storage. It would be a pity to fry those rare chips.
I remember a PC (286) brought in for repair that had blown a fuse in the power supply.
Nothing was visibly wrong, so I replaced the fuse and jokingly said, "Well it's either going to work, or it's going to explode".
I turned it on and the CPU promptly blew itself to bits. Literally "Bang" and the CPU was a few shards stuck to the pins (286 was soldiered directly to the main board).