New 5e3 build, faint sound..

[scottb1966]

Another common error is to swap the 100 ohm filament balance/ground reference resistors with one or more of the 100K resistors on the plates of the preamp tubes.

I did that and you caught it from looking at the pictures I sent!

When I fired the amp up for the first time, all the tubes lit up but no sound. There is a shielded wire from the volume pot to a preamp tube. I did not trim the shield good enough and one tiny wire was touching a lug on the tube socket. After I fixed that, glorious sound!

Don't know if the Triode kit has the shielded wire, but if it does, check it.

[01bcat]

Jazz,
I should have worn both pairs of glasses! - operator problem.

Try Again:
12ay7
1-120 2-0 3-2 4-3ac 5-3ac 6-115 7-0 8-2 9-3ac
12ax7
1-150 2-0 3- 1 4 3ac 5-3ac 6-114 7-0 (am radio though) 8-0 9-3ac
The 6v6 heater elements check out too.
thanks!

[01bcat]

No sheilded, cloth pushback wire. Thanks though.

[01bcat]

Hey Jazz,
Operator problem, added another pair of glasses...
12ay7:
1-120 2-0 3-2 4-3ac 5-3ac 6-115 7-0 8-2 9-3ac
12ax7:
1-150 2-0 3-1 4-3ac 5-3ac 6-114 7-0(with am radio) 8-0 9-3ac
The heater elements check out on the 6v6's as well (the other info on them should be accurate)
Thanks!

[Bruce / Mission Amps]

Hey Jazz,
Operator problem, added another pair of glasses...
12ay7:
1-120 2-0 3-2 4-3ac 5-3ac 6-115 7-0 8-2 9-3ac
12ax7:
1-150 2-0 3-1 4-3ac 5-3ac 6-114 7-0(with am radio) 8-0 9-3ac
The heater elements check out on the 6v6's as well (the other info on them should be accurate)
Thanks!

Filaments are fine.
Radio on lug 7 is bad...
Check lug 8 of the 12AX7 with respect to ground... it should be at least 35vdc to 60vdc in order for the tube to even turn on.
I suspect an error there... maybe too many glasses now though.

[01bcat]

Hey Bruce,
I can't help the eyes much - but I will check it out - thanks...

[01bcat]

O voltage on pin 8, also none across the cap it is connected to... ?????

[01bcat]

Its Alive!
Thanks for the help, I missed a connection under the board.
It is humming like crazy, but the tone is there, just need to clean up the wiring, maybe change some grounding as Zephyr suggested.

Zephyr- can you tell me the changes you made to the grounding?

Bruce, your comment led me right to it.. Thanks.

[Chuck H]

The hum could be another wiring error. Miswired grounds can hum but a bad hum is usually indicative of a bigger problem like a miswire or a cold solder joint.

Chuck

[01bcat]

Chuck,
I am going to go over everything once more, an re-do the heater wiring.
My volume goes from nothing the really loud in like 1/100s of a turn, if I dime it (or $0.12 it in this case) it squeals.
Any suggestions on where to look for the cause there?

[rudutch]

a volume pot lead contact to ground (due to rotation and not much room) will cause problems too

don't ask how I know this

[Bruce / Mission Amps]

It also sounds like an input jack could be wired wrong and or not grounded right.
Short lugs 2 and 7 of the first preamp tube right to ground with an alligator clip lead and see if that kills the noise.

[01bcat]

Thanks, I will do that. There is NO clean headroom either.

[01bcat]

OK - Stupid question:
If I touch the leads dropping to the 68k resistors on the normal input jacks, it shows continuity with ground. The brite jack leads do not. Normal?
Thanks.

[Bruce / Mission Amps]

No... the switching jacks should have the two resistors grounded at the input jack end.
I think that point should read about 32K-36K range on both pairs of resistors with nothing plugged into the jacks.