Hacker News Reader

Comment by randrews | Hacker News Reader

For those wondering why this exists: the original C64 PSU has a (common) failure mode after a few decades, where it will output power in such a way that will destroy the C64 (and its irreplaceable MOS ICs). If you find an old Commodore and you want to test it, don't plug it into the original PSU without testing that first with a multimeter!

View on HN

The VIC20/C64/128 PSUs have standard 5V DC AND also have 9V AC pins to power the SID chip (among others). Which means it's not that easy to just pick up a standard transformer and wire the right connector onto it.

A lot of the new Commodore and Amiga Hardware being developed these days is open source, which is 100% a great thing, enabling us to keep these classic machines running for many years yet.

However, it is quite easy to pick up two standard wall warts of the right amperages, and reuse the old PSU's cable.

It seems like it would be pretty easy to just have a step down transformer from 120VAC to 9VAC. Also wire up the 9VAC to a bridge rectifier to get 9VDC to then convert down to 5VDC with an LDO or buck regulator of proper current rating. It wouldn't be the cleanest power supply but the C64 board should have proper filtering for each rail.

And if I recall correctly, you can't just repair them as all the parts are in a solid block of epoxy.

I remember that bit of fun all too well... or I am going senile...

Back when these things were new and shiny, I had a power supply go and I was pretty sure it was just a fuse. Easy change.... except for the fact it was, as I quickly learned, a de facto fossil inside a beige-ish (as I dimmly remember) block of solidified goo. I was wondering why it was so hard to get the power supply case off...

That does explain why the damn thing felt like such a brick.

The whole thing was prone to overheating IIRC, which shortened its life. Being completely encased in resin probably didn't help the heat dissipation.

Reply on news.ycombinator.com