Power Supply Question

[Hank Rearden]

Both of these work. I have a RevA 326298 original C64 board and need to know which of these 2 power supplies likely came with it. The board does not work and I plan to list it on Ebay with the original box and working power supply but need to know which of these 2 is the one the likely came with it.

 

[carlsson]

I'm not an expert but I think the one to the left predates the one to the right. The one to the left supposedly is possible to disassemble and repair, unlike the later ones that were filled with epoxy and glued shut, in order to not make it servicable.

 

The schematic for the power supply might be the same, but this one should match the left one:

http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64/c64extps.gif

[Hank Rearden]

I'm not an expert but I think the one to the left predates the one to the right. The one to the left supposedly is possible to disassemble and repair, unlike the later ones that were filled with epoxy and glued shut, in order to not make it servicable.

 

The schematic for the power supply might be the same, but this one should match the left one:

http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64/c64extps.gif

Thanks. They both work so that's the good news!

[motrucker]

Both of these power supplies are dangerous to use however! Should not be used without a computer saver, or Sav64 unit.

 

 

[7800fan]

The uncommon brick that can be opened can be serviced to have unreliable parts replaced and saver installed inside. The one that can't be opened, either get an inline saver or cut the cable and dump the brick, use the cable on a new custom built 5v DC and 9v AC adapter brick.

[Hank Rearden]

The uncommon brick that can be opened can be serviced to have unreliable parts replaced and saver installed inside. The one that can't be opened, either get an inline saver or cut the cable and dump the brick, use the cable on a new custom built 5v DC and 9v AC adapter brick.

Maybe I'll keep the one that can be opened up. Are there instructions somewhere for servicing it so it is more reliable? If it's fairly straightforward I might give it a shot.

[carlsson]

I'm not sure if the original design can be serviced to prevent the linear part going bad and outputting 9V on the 5V line. You can however remove that part and install a new solution, perhaps switching power supply, inside the original case. A few people have done that:

 

http://forums.overclockers.com.au/showthread.php?t=1037645

https://wej.k.vu/broken_stuff/c64_power_supply_repair/

etc

 

In the market of overvoltage protectors, so called C64 savers, there seems to be fierce competition. Ray Carlsen's solution is well known, but there are a few others trying to outperform his build. Here is the latest version of the EasyEDA solution, said to be something of the ultimate in its field:

https://easyeda.com/example/Uberclamp_Schematic_PCB_and_BoM-r4YgysK2k

 

I suppose you could install some sort of saver inside the PSU but if you're going to make alterations you might as well want to rebuild it to be safe to begin with. Apparently you can crack open the one filled with resin (epoxy?) as well, though it will be more work.