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Posted by: starhawk
Posted on: Jul 17th, 2018, 8:31pm
Oh right. There is one further issue with reverse-engineering the Org2. It appears some corners were cut in the most unlikeliest of places, presumably because the devices were maybe a dollar too expensive or something. I'm really not sure why, actually -- but the PSION Organizer II is one of two places (the other being the keyboard for a Tiger Electronics Wheel-of-Fortune electronic game, where cutting corners until there's hardly anything left is quite reasonably expected) that I have ever seen what are called "carbon deposition resistors".
If you open a PSION, working or otherwise, and you look at the back of the mainboard, you will see several SMT-resistor-sized black "pads". What PSION has done there is to print carbon-composition resistor material directly onto the PCB. This has two effects -- one, it makes that component that much cheaper to 'put down' -- and two, it makes it utterly impossible to determine the actual resistance of that part without literally cutting a chunk out of the board.
Remember, passives cannot be accurately measured in-circuit, because of current leakage into the rest of the circuit... and if you can't remove the part without destroying it... yeeeaaahhh that's gonna be an issue.