exxos's Atari, Amiga & retro forum

If the ground checks out, then it has to have come from somewhere. Are either of the switch wires for the ct60 burnt? You'd almost want to decap that blown chip to trace the path of the fault. Typically as you know, you'd have a ground pad under the cpld chip, so exploded chip, shorts to ground, causes other damage through the common ground.

Just a thought, is the power supply fuse blown? If not then the source has to have come from before the fuse OR the fuse is faulty or not 2a as marked on the PCB.

Fuse on the psu tests ok. But it's after the mains PCB, so not sure it would help if the short is between the mains connector and switch. Theres no fuse there to blow.

That's the thing again.. The only mains voltage is on the switch. But that means it would have had to arc inside the switch, then to the GND track AND the ct60 wires. Would need a few thousand volts to jump that lot.

I'll try and desolder the PCB tomorrow. I did test the switch with my meter and nothing seems "bad".

Well you'll not get your thousand volts as there's no way to generate it at that point, other than extraneous circumstances, ie lightning strikes house, so switch and PCB failure seems the logical path. If the PCB or switch has carbonated, then there's your path, no high voltage required.

If the PCB got hot enough to be toasted, possibly from the switch overheating due to a poor contact causing internal arcing, then eventually it will become carbonised internally and become conductive. The AC mains supply will then be giving +140V then -140V relative to “earth” through the cycle. (Remember that it’s 230V root mean square, so the peaks are far higher.)

So the +5V rail would be swinging between +140V and -140V 50 times a second. Not good for TTL logic.

Hopefully the Falcon’s PCB hasn’t become charred and conductive too.

Totally agree @stephen_usher

I removed the switch from the PCB.


I have decided not to spend my time diagnosing or fixing the CT60PSU itself. It is another company's product, and the owner has contacted them several times without getting anywhere. A proper investigation of a mains fault also needs to be documented step by step, and ideally done independently, in case the owner wants to take it further. That is not something to do half-heartedly on a hobby bench for free. I am happy to give up an evening for the community, but unpaid product development for someone else's power supply is a step too far.

For everyone else, I am not calling a verdict, because the cause is not known. But until it is, my advice would be to stop using the CT60PSU, and especially the combined mains and mode switch.

Makes sense to me @exxos. It's clear there is a problem around the PCB, mounting bolt and PCB.

Maybe the exxos community could come together to help design a safe replacement for this forums effected user? What other forums, users or companies want to do is up to them.

Not hinting at you doing it @exxos .

@PhilC probably the safest way is to go the Pico route and just have the 12 volt power supply hanging out the back for the time being.. not that I like the Pico design, but maybe there is something like that but better these days..

Designing a thing from scratch would not really take long. It's getting everything to fit and then making it safe, measuring everything, then building 3D printed things. That's where all the time goes.

exxos wrote: 06 Oct 2026 11:53

HigashiJun wrote: 06 Oct 2026 11:49 I also find quite strange the same issue happened twice to the same guy and I would like to know more about his setup and use.

Not just the same guy.. 2 other people that we know of..

When I was a bit younger I worked for a computer repair company, and it was situated in a smaller town, it was amazing how many PSU's/mb/modems I had to replace just because of overcurrent conditions and lightning strikes, it was at leat 3x as much as the computer store in the city..