no speaker output, blown OT?

[vigs]

hey all,

first, hello, this is my first post so be gentle.

to the meat... i picked up a 36w TMB head built from a kit on craigslist the other day. apparently the person i bought it from acquired the amp from it's original builder and used it at a rehearsal for about 2 hours with no problems. then, he took it to a gig and during the gig it started having dropping power problems and a loud hum/buzz. he hadn't fired it up from that time until i went to buy the amp. during my testing before buying, the amp produced no output whatsoever. no thump when flipping out of standby, no hum, no nothing. i tested again with a different cab and it was no different. mains and B+ fuses are fine. tubes are supposedly brand new but i have yet to test a different set. in fact, i have don't no testing yet but that's why i'm here.

my first suspicion is a blown OT since there is no output whatsoever. if tubes were shot, there would still be SOME sort of noise. my testing will begin today but i wanted to get any other ideas besides the OT. that will be the first test and i'm relatively sure i'll find that it's shorted out. but what other problems might cause absolutely no output at all?

[Chubsman]

BTW always unplug from wall and drain the filter caps before you screw around inside.

Start by mesuring the fuses... just looking at them sometimes is wrong... should mesure a little below 1 ohm.

I would remove the power tubes and mesure the resistance from end to end on the OT primaries and it should be double what it is from end to center tap and other end to center tap.

Still with no power you can mesure the OT secondaries They should be about 3-9 ohms from Common to tap.

Still with no tubes, you can mesure all the voltages. Get the chart in the download sections. If they look ok (probably 10% more than with tubes in the amp).

Start with that.

[vigs]

thanks chubsman.

as it turns out, the lack of output was due to (wait for it), no tubes in v2 or v3. haha. cost the guy i bought it from about 40%. oh well.

with tubes in the positions as they should be, the amp makes noise, and a nice noise except underneath the nice tone, there is a very harsh distortion that only appears as you turn up the volume on either channel and comes on during attacks, quits as notes ring out. it becomes more and more prominent the higher the volume is.

seeing the inside of the chassis, it's an ok job. not the cleanest soldering but it's not terrible either. chopstick poking revealed nothing of interest, all connections seem ok. one resistor on the rectifier looked slightly burnt in the middle, but it looked to be from sloppy soldering, not failure. all electrolytics look ok. no charred leads, nothing obviously wrong.

i'll do proper testing of the OT today just in case but i see no reason it wouldn't be fine right now. any thoughts as to the distortion? it happens on both channels and is volume dependent. hmm