Laney TT50H No Outout

[ca7922303]

Sounds like the hum balance pot is bad. Measure resistance from each lug to ground.

Hum Balance Pot(O.Lm ohms/O.Lm ohms/99 ohms)

[g1]

Sounds like the hum balance pot is bad. Measure resistance from each lug to ground.

[ca7922303]

Then measure VDC from ground to each end of R52, and from ground to each lug of hum balance pot.

R52(0.0/0.0mvdc)
Hum Balance Pot(316vdc/316vdc/0.0mvdc)

[g1]

Then measure VDC from ground to each end of R52, and from ground to each lug of hum balance pot.

[ca7922303]

Measure DC volts directly across R52 (one probe at each end of resistor).

R52(one probe@each end=0.0mvdc)

[g1]

Measure DC volts directly across R52 (one probe at each end of resistor).

[ca7922303]

I thought all channels were now not working, even Ch.1
If so, yes this wire being off (if coming from input jack) would mean the input jack would not work.

I am extremely grateful for all the help. Reconnected P1 and now have output from all three channels. Really appreciate it. Not to damper the situation, have 313vdc@hum balance pot(same voltage reading at V1-V6 at pins 9 & 5/4) and slight hum on channel two at all volumes. Thanks.

[g1]

I thought all channels were now not working, even Ch.1
If so, yes this wire being off (if coming from input jack) would mean the input jack would not work.

[ca7922303]

You have the amp, we do not. You can see what INPUT P1 is, but we only have the schematic. If you can locate it on the schematic and tell us what area it is in, that is very helpful. Or post pictures.
If it's related to the input jack, that is probably why you have no sound using instrument input jack (all 3 channels).

It's right next to hum balance, V1, R6, it goes to main preamp board plugs into component side, in front of input jack. I haven't taken out main power board since channel one was working. Not sure how that wire came loose, but wondering if it could cause the 310v on hum balance pot along with channel one working and two and three not working?

[g1]

You have the amp, we do not. You can see what INPUT P1 is, but we only have the schematic. If you can locate it on the schematic and tell us what area it is in, that is very helpful. Or post pictures.
If it's related to the input jack, that is probably why you have no sound using instrument input jack (all 3 channels).

[ca7922303]

Did R52 or the hum balance pot burn again? If there was really 300+V across them, something would burn.
If they are all okay I suspect you have lost a ground somewhere. One end of R52 should be grounded, and that end should measure zero ohms to the grounds on the other circuit boards.

Hum balance pot has not melted like previous one and haven't seen it glow thru adjustment hole in board. R52 reads 98.3 ohms and reads 0.0 ohms on one end to various ground points. I noticed when looking at hum balance pot underneath board that bottom side of INPUT P1 has disconnected. Could this be causing issue? Will have to remove main power board to resolder.

[g1]

Did R52 or the hum balance pot burn again? If there was really 300+V across them, something would burn.
If they are all okay I suspect you have lost a ground somewhere. One end of R52 should be grounded, and that end should measure zero ohms to the grounds on the other circuit boards.

[ca7922303]

Measure resistance from that wire to pin #1.

134k ohms

[g1]

Measure resistance from that wire to pin #1.

[ca7922303]

No, can't really tell from those readings.

Was able to see V5 socket by pulling tube and measured start of copper wire than I ran to pin#5. Getting 0.0 ohms resistance and not able to see any door or burn marks from arching?