Power Supply and Curious Outcome

This is non-critical. Just (to us) interesting.

I bought the following from a Roon Community member. I used to between the wall and my NUC.

Worked fine.

One night, I heard the NUC fan whirring away. The power supply was extremely hot. I took it out of the system.

I wrote to the manufacturer (cannot recall the brand but mentioned here in the past often) and offered to send it to him since it may be something that would interest him. I told him that I bought it used, that it had no warranty and that he did not need to return it but felt it may be interesting to him.

His response was…well…ungratifying.

So I still have it. I plugged it in (with top removed) and testing to see if it overheats again. It is not powering the NUC. It is just sitting on a shelf.

Any thoughts as to why it would have (after several months) become incredibly hot? There are no signs on the board or capacitor that it had burned etc.

I don’t recognize the brand but I gotta say the faceplate is probably the best looking one I’ve seen on a power supply. It’s a linear supply, correct? Brand’s not on the rear or bottom anywhere?

Looking at the transformer, it has 2 x 25VA secondaries. Is 50VA total enough juice for your NUC?

If the NUC fan was running, it was probably working pretty hard. Heavy DSP or local library indexing? The power consumption at full chat might be more than the PSU can deliver?

Another thought - what’s the output voltage? Tranny secondaries are 15V, which after rectification and smoothing are going to be pushing ~21V DC.

If it’s regulated, an output voltage significantly below 21V is going to fairly heat the regulators up at high current.