Capehart Troubles...

[jpdylon]

My first powerup after the recap revealed a hum in the sound, and no raster. HO tube was dead, so I got another.

Second powerup reveals hum in sound, no raster, but I can hear singing, so at least the oscillator is working....


and then...

it all stops working, leaving nothing but the tubes lit. I power down, check the underside for failed components, overheated parts, etc. All fuses intact. LV rectifier checks good on my tester.

Power back up, and the 5u4 lights up in a shower of sparks for a second. Pulled rectifier and replaced it. Powered up again. Same dead set symptom with tubes lit, but the rectifier is making this buzzing rattle, like internal elements are loose or something. Again, no fuses are blown, transformer is cool, and no excessive current draw from the variac.

WTF happened? I was getting so close to first light...now nothing. I hope the transformer didn't crap out

Right now its down in the mid 30s and my workshop has little to no heat. When I do get a chance to get back out there to tinker, where should I start looking to resolve this problem?