'61 Ampeg R12-R Hum

[ca7922303]

Constant hum, volume control has no effect on hum. Removed PI(no hum)
Removed 6SL7's/6SN7's
Reinstalled
V4 socket only with any of four(4) tubes has hum.
Amp appears to be original except 3 prong power cord, death cap removed, and 2 caps shown in photo. All tubes are Sylvania.

[ca7922303]

Constant hum, volume control has no effect on hum. Removed PI(no hum)
Removed 6SL7's/6SN7's
Reinstalled
V4 socket only with any of four(4) tubes has hum.
Amp appears to be original except 3 prong power cord, death cap removed, and 2 caps shown in photo. All tubes are Sylvania.

Meant for title to read Ampeg R-12R(Reverbrocket)

[g1]

schematic attached

[ca7922303]

schematic attached

Thanks, the two resistors soldered to pins 3 & 6(220k & 1k) are good. Issue with this amp is hum is too loud for recording but is in good operational condition otherwise.

[ca7922303]

schematic attached

Im seeing a cap set on fliptops. Would rather find the exact issue though.

[nosaj]

What is the current draw on the output tubes? They should be pretty close
nosaj

[ca7922303]

What is the current draw on the output tubes? They should be pretty close
nosaj

V5(47mA)
V6(27mA)
Using a eurotubes bias adapter.

[nosaj]

Well there you go possible hum with unbalanced tubes.
Nosaj

[ca7922303]

✓-appreciate the help. Will install different 6v6's and retest.

[ca7922303]

Well there you go possible hum with unbalanced tubes.
Nosaj

Didn't have a spare 6V6 so used two(2) 6L6's. Now V5(51 mA)
V6(51mA)
Hum is as loud if not louder at this point.

[nosaj]

Do you have a scope?
nosaj

[ca7922303]

Do you have a scope?
nosaj

PC based.

[nosaj]

Have you scoped the signal from the PI to the speaker out? I presume you know how to properly do this?
nosaj

[ca7922303]

Have you scoped the signal from the PI to the speaker out? I presume you know how to properly do this?
nosaj

Can you elaborate?

[nosaj]

Here is some reading for you.
nosaj