Hi katiekat8000, I think from my recollection the ROM chips can get mighty warm. The VIC 20 and the C64 ROM chips as I remember correctly get very very warm too. It must be something to do with how they were designed. I know that replacement for EPROM'S lowers the power consumption considerably of t...

Hi katiekat8000, Sorry to hear you're disk drive isn't working. Make sure to check for correct voltage levels at several IC chips. Nothing above 5.2v and check for a 12v. Possibly these chips could be something to look at further.... Two 6522 VIA chips 6502 CPU Both the Disk drive ROM & KERNAL R...

Yes,. That would be very nice.

Hi Dave2468, Very interesting failure issues. A quick question. Have you tested the power supply under an external load for extended periods and measured the voltages and currents? When using these old computers I highly recommend an overvoltage protection device. https://www.gamedude.com.au/brands/...

Hi rfxcasey, Sounds like you have a good range of test equipment. That will definitely help you in testing. I once found when trouble shooting a C64 board the actual rocker power switch was not making good contact. I would always test good on all the various voltages around the board as one would ex...

Hi rmzalbar, 5VDC (directly feeds RAM, logic, some MOS ASICs) 9VAC (feeds 12VDC and 5VDC linear regulators that supply VIC-II and SID) These both come through the power switch which tends to become intermittent, check that Gee, I became a victim of an intermittent power switch. I actually had no ide...

Hi rfxcasey, Can you open up the power supply? If you cannot open it and replace the linear power regulator I wouldn't trust it. I would strongly suggest that you get an over voltage cutoff device as well. Something like this... https://www.gamedude.com.au/brands/shop/ovp-64-over-voltage-protector-b...

Would this do the business?


https://www.etsy.com/au/listing/1124333 ... 232-serial

One question about this item. Flicking through the pictures I noticed 2 different connectors. Do these different connectors do different things or are they the same?

Very interesting discussion.

What are the voltage levels for RS232 standard?

Would some type of level shifter be used here, or are there off the shelf devices that achieve this?