trinityamps.com

flubbed the control pots. argh.

edit
maybe twice. no signal. try try again!

Backwards?

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http://pdfelectronics.com

I thought they must be backwards..
so I reversed them, but now no signal at all.
so back I go.

as of now:

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Got it... had one thing in wrong... gets pretty confusing for this old fart when stuff is that messy.

Everything works fine. Gotta run an errand and then test voltages.
Will come back with results.

Using and old RCA 6L6GC and a Ruby 12AX7 for test tubes.

quiet when gtr is down.
seems very nice.

I'm doing a little dance here.

just saying.

12ax7

all heaters 6.3

pin
1 206
3 1.8
6 204
8 1.8

I have a 330R cathode couldn't get a reading. may have battery dieing

6L6GC

pin
3 434
4 430
8 61.3

3/8 372

I think that looks pretty good.. comments welcome

I found this for voltages
Measured resistance of Cathode resistors (switch in 6L6 position) = 321 Ohms
6L6 pin voltages:
Pin 3 = 393 VDC
Pin 4 = 390 VDC
Pin 8 = 27 VDC
but he's set up for 6V6 and I'm just a 6L6GC

trying to find out what others have..any hot cold bias argument.. etc.

found the cathode R was bad.. took 2 min or more to get up to 300R
dumped it for a handy 360R
tests immediately so I had a bad R in there.

I didn't test voltages further, because on recheck and rethinking I not only had the
bad R but 417 on P1 12AX7.. leading back to that R again cinched it, on top of the earlier
goofy voltage readings.

What I didn't expect when I checked just to see if it would produce sound was
that I'd spend the next 20 minutes playing it without the needed test.
It sounded soooooo good I got carried away.

Crimeny ZP... what a monster tone machine. Even in the sorry state this one is in right
now.

Ok new cathode R in. 330R, actual 326.

B+
399, 398, 393

plate 392
screen 390
cathode 24.8
plate/cathode 367

pre
1, 208
3, 1.5
6, 200
8, 1.6

all heaters 6.4

The 100R dropping R is dropping 1 Watt, so that could be a jumper.
I have some hum now, so I'll start with the lead dress and htr routing for that.

gained a volt or two removing the 100R.
No changes in the preamp.

pull out on tude switch.. big electrical noise.
???
where could that come from? went all over the front end, nothing is different from when
it worked fine.
no volume, it seems-quick test, until bass pot is up.
fat thin works fine. all pots function normally.

I expected some hum but it was quiet when I had the dang thing wrong.
Now I have hum.. that kind of makes me think bad or damaged component.

any hints? I'm going over the front end to see if I can have less wire crossing and maybe some shorter wires.
But it puzzles me that the hum showed up so late.

I got it. tiny wires shorting the NFB, big squeal.

Sounds good. still a little bit of hum.
better dress and some shielded wire here and there should do it.

edit
tried several changes but still have hum.
the front end is such a complicated and close mess I may never get rid of the hum.

I found what I did wrong.
I think.

I think I'll pull the fat/thin switch.
just to reduce wiring.. and go from there.
I may have to just redo the front end.
hummmm. argh!