is this power transformer toast?

[acorkos]

mesa triple rectifier with one power tube powdery white inside on top. no fuse, and fuse holder cap missing.

i replaced the bad power tube, installed a new fuse holder and fuse. turned on the mains switch...pop goes the fuse. i took out all the power tubes and rectifier tubes, put in a new fuse, connected my light bulb limiter. turned on the mains switch....bulb lights brightly.

disconnected the red high voltage leads to the rectifier board....no bulb lighting. I disconnected the limiter and plugged straight into the wall....fuse holds and all the power lights light up.

i measured the dc voltage from the red high voltage leads with the amp on....zero volts.

Is there anything else i should check, or is this transformer bad? thanks for your help.

i'm suspicious of the missing fuse holder cap...like maybe someone spilled beer on top of the amp, splashing onto the one tube, causing a short and blown fuse. and maybe someone jammed some tinfoil into the fuse holder...?

[stokes]

When you disconnected the "red high voltage leads" from the rectifier,all you had powered up was the PT,so it appears the PT is okay.If it was bad,you would get a short indication from the current limiter.You cant measure dc voltage from the red leads,they are ac leads.They get converted to dc when they are connected to a rectifier.You can read ac voltage across the two leads or from each lead individually to ground,but not dc with no restifier.The fact that you got a bright bulb with all the tubes out indicates that either your solid state rectifier is bad,your filter caps are bad.It is also possible that when the first tube(s) went bad they could have taken a screen resistor with them,but that wouldnt show without tubes installed.Dont power that amp up without the current limiter till you completely trouble shoot and find all the problems.

[acorkos]

thanks. it was 2 of 4 shorted ss rectifier diodes.

[Enzo]

Replace all four, who knows what stress the good ones saw while the other two failed. rectifiers are cheap.