[mole42uk]

A much improved Sunday morning. After some testing of the main regulator by supplying 70V across C5 and measuring 5V and 16V at the correct places, I decided to assemble the pre-regulator and test the whole thing.

Winding the Variac up from 0 towards 100V I was rewarded with acceptable DC levels at 5V and 16V, a little higher than I'd like but that's what you get running an SMPS without load.

Shortly after I'd begun to congratulate myself there was a huge 'crack' and the 1µF tantalum at C55 keeled over. After settling my nerves and replacing that with a proper electrolytic, the output looks good, I even wound up to 160V while measuring the 70V across C5 which remained within limits.

I'm having a break from the bench now. I will be testing the other power supply next, and replacing all the tantalums as a matter of course. Is it permitted to hate tantalum bead capacitors?

There's also the EHT supply to test. I have an EHT probe so we'll see if that works.

The other photo is of parts that had also failed - a couple of diodes, a resistor and some tantalums that I outed just because they were there.