Voltage doubler, let some smoke out!

[Phil_S]

I have no idea what's wrong here, but I smoked the pair of diodes at the bottom of the picture.

This is a classic basic Grienacher voltage doubler, just tacked together for the purpose of testing this PT. All solders have been double checked, though a couple look iffy in the picture. The PT is unknown, with several windings that meter across the outer legs, under no load 252vac, 212vac, and 68vac. I've got the 252v winding hooked up. I measured 320vdc before the smoke came out, which happened quickly. There was also a loud transformer hum that isn't present when powered up without the load.

The idea was to test it with the doubler under load to get some idea of mA capacity. and acutal results. I've since increased the load from 3k5 to 5k8, and replaced the diodes. But I don't have the nerve to fire it up.

The test is simple. Given the size of the iron, I'm thinking 320/3k5= 91mA and that should not have been a problem for the tranny (it's a big one) or those diodes. The diodes are a pair of n4007 in series, and should be good for 2000v @ 1A. Maybe my guess about the mA rating of this one is wrong? I realize it is about cut in half by the doubler.

The doubler schematic is here, the first one on the page:
http://www.kronjaeger.com/hv/hv/src/mul/

I'd appreciate a little help. Thanks.