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Hello everyone. I'm stumped and could use some input. I've double and tripple checked my work, and for some reason my voltages are low on V1 and 2. That's as much as I could test before I smelled smoke.

I've got 1 extra EL84 to test with, but before I swap tubes what should the voltages be if I take the power tubes out?

The resistors feeding pins 3 and 8 are reading 850 and 830 respectively. This seems off... Is it enough to throw things off that much?

The resistors feeding V1 are reading 33k each and I can't get a reading on the meter if I go across the tops of those 2 resistors (effectively testing the total impedance of the high and low input of one channel? right?)

The resistors coming off the B+ can cap (is this what it's called?) are reading: 120ohms (in paralell with the 470uf) and around 8 (next to the 1st 16uf cap) These values are a little low too..

I don't know how to check a transformer. But I would like to make sure the output transformer is okay. I have reason to think it might not be.

I think I've got everything else eliminated. I've got some pics at http://www.bradovka.com/trinity/tmbmv/detail/ they're mostly detail of the tube wires...

Anyone have any thoughts?

V1 - 12AX7
--------------
Pin Volts
1 130

6 130

V2 - 12AX7
--------------
Pin Volts
1 123
6 238
8 127

Problem solved. It was bad power tubes. Got some new JJ's from Stephen and everything sounds great.

When I tested the EL84s, one of the tubes was really bad, the others marginal.

To check the amp out, we measured voltages on V1-3 without the EL84s installed to see if the voltages would would rise significantly and they did - about 60V!

So folks, if you have really low voltages with a decent B+ before tubes are inserted & funny sounds, don't assume all the tubes are OK.


After going over Adams amp in the shop in Tronoto, I know the build was of first rate quality. His attention to detail, checking against the layout and wire dressing was first rate.

Good Job Adam! Enjoy your new TMB.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Thanks a lot Stephen!

I appreciate you spending some time on it.

I wired up the 2x12 to switch between mono and stereo output and it works great. My neighbours should appreciate that.

I intend to get some playing time in now that I'm not hunched over a workbench. Maybe I'll post some clips.

Peace,

Adam

Right On! Clips are good. Put them into the Clippage section!
Looking forward to them.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps