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This is my 4th amp, second 18 watt. They always start right up, no issues at all, but there's a first time for everything.

The symptoms: nothing at all out of normal channel, very low output, spitty, horribly distorted out of TMB channel.

First: Voltages

AC Mains 120Vac
B+ 359V
at OP + 342

Skipping heaters on chart

V1 158/-/1/-/-/147/-/1.1/-
V2 210//-/1.9/-/-/291/-/212/-
V3 216/64/96/-/-/211/63/96/-
V4 -/-/12/-/-/-/347/-/341
V5 -/-/12/-/-/-/347/-/341
V6 295vac/-/360/-/-/-/296vac/-

Testing voltages does cause popping through speakers.

What I did:

Checked, double-checked and rechecked layout to make sure everything is wired correctly. I decided to be fancy this time and have my flying leads (mostly) under the board. They were checked by continuity.

Checked grounds, all at fractions of an ohm.

Replaced 32/32 500V cap can (suspected filtering).

While checking the PI socket, touching pin 7 gave me the slight hum and whoosh of a properly running amp. Plugged in and TMB channel had good output. Then it went back to low, spitty and distorted. I assumed there was a bad solder joint and redid the entire socket. Turned it on and all back to NG.

Rewired input jacks.

Checked continuity of shielded leads and made sure ground were isolated with plug in socket. All look good.

Reflowed anything that looked marginal. Board was built by Trinity and looked wonderful, but I still checked through.

Suspected OT, but the short time I had with good output and the popping while testing lets me think it's OK.

Installed known good tubes (My Lightning is naked now!!)

At wit's end here, I don't know where to go next.

All the voltages look good. Assuming good tubes then, I would suspect woring or a component failure.
Do the click and pop testing of all the grids working back from the output tubes and see what you can get for a clue.

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

Some progress. I did flying leads on the bottom of the board for the first time because it looks so cool. Obviously I don't know what I'm doing.

I removed the controls to allow me to flip the board. Reflowed every joint except 2 which just didn't look right to me. I reconnected these to the top of the board, wrapping the turret as I like to do.

Now Normal channel works fine, loud, clear and sounding good. There is a little background sputtering but I'm sure it's related to TMB channel problems.

TMB is still low in volume, spitty and distorted. Since Normal channel bypasses V2, while TMB channel doesn't I'm going to concentrate there. I've got my Saturday morning cut out for me.

Still, it's good to make some progress, I was tearing my hair out (well proverbially, my actual hair is long gone).

Paul.

Yes, concentrate around v2 and the controls around that.

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

'I give up.

Tomorrow I'm stripping the whole thing down and rewiring from scratch. This is just weird.

Normal channel sounds good, so OT, PT, PI and Power section are fine.

Nothing plugged into input jack hums real bad like open circuit.

Either a coupling cap is dead and wide open or I screwed up the wiring, although I can't find anything.

I have no way to check caps, although I'm sure I didn't overheat anything, so I'm rewiring from scratch, top of the board.

Wish me luck.

Frustrating, but I'm gonna beat this!!

P.

Before you take it apart. I suggest you trace the corcuit through per the schematic just to make sure the board is done correctly. And continuity check to all connections.

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

Too late, I did rewire everything, to no avail.

Connections have been checked and double-checked.

But, went over board with layout and schematic in hand and found one error. Moved one jumper and IT'S ALIVE!!

Sounds killer. It's been put in a cabinet, and is getting packed into my car for tonight's gig for a trial-by-fire. Bringing the first head as a spare, just in case, but after all that work and rework, I'm confident every solder joint is as solid as can possibly be, so YAY!!

P.

I admit it, I made the mistake, not Paul. But we all learned something.

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

No worries, I'm just happy to have the amp ready, and my wife is happy to get the kitchen table back after a week and change.

P.