Laney TT50H No Outout

[ca7922303]

Ok, the hum balance thing is all good now.



Heater voltage for V1 to V5 is missing. Under this condition there would have been no sound so this has happened since post #340.

Tested signal and then took the readings were the only things done.

[ca7922303]

Ok, the hum balance thing is all good now.



Heater voltage for V1 to V5 is missing. Under this condition there would have been no sound so this has happened since post #340.

Tested signal again, same results as before but also noticed on channel 2 drive pot is somewhat intermittent and 1 power tube trying to redplate with gain in full and volume/master volume nearing full. Does not seem to be at full power though. Definitely channel one (1) is not. Then I found a piece of solder wedged into the inside of hum balance pot. Removed it and now have readings of:
R43(443/362vdc)
Hum Balance Pot (1.1/1.1vdc)
R52(299/0mvdc)
V1-V5 pin #9 to 5/4(6.0vac)
V6 pin #9 to 5/4(7.0vac)
V1 1 & 6(229/248vdc)
V2 (310/248vdc)
V3(356/196vdc)
V4(12/223vdc)
V5(356/202vdc)
V6(271/263vdc)

[ca7922303]

Tested signal again, same results as before but also noticed on channel 2 drive pot is somewhat intermittent and 1 power tube trying to redplate with gain in full and volume/master volume nearing full. Does not seem to be at full power though. Definitely channel one (1) is not. Then I found a piece of solder wedged into the inside of hum balance pot. Removed it and now have readings of:
R43(443/362vdc)
Hum Balance Pot (1.1/1.1vdc)
R52(299/0mvdc)
V1-V5 pin #9 to 5/4(6.0vac)
V6 pin #9 to 5/4(7.0vac)
V1 1 & 6(229/248vdc)
V2 (310/248vdc)
V3(356/196vdc)
V4(12/223vdc)
V5(356/202vdc)
V6(271/263vdc)

V4 pin #1(12vdc)?

[ca7922303]

Ok, the hum balance thing is all good now.



Heater voltage for V1 to V5 is missing. Under this condition there would have been no sound so this has happened since post #340.

Have all three(3) channels working now(changed the preamp tube with the 12v reading). Still seems to not be at full power and both drive controls on channels 2 & 3 have a loud sequel when near full.

[ca7922303]

Ok, the hum balance thing is all good now.



Heater voltage for V1 to V5 is missing. Under this condition there would have been no sound so this has happened since post #340.

Changed both power tubes and issue still exists, one of the power tubes is trying to red plate when drive and volume/master volume approach 10. Amp is not putting out full power on any channel.

[ca7922303]

Ok, the hum balance thing is all good now.



Heater voltage for V1 to V5 is missing. Under this condition there would have been no sound so this has happened since post #340.

I'm also noticing that the readings that I have been taking at R43 and pins 1 & 6 V1-V6 all go down about 10% when the drive is turned all the way up. All except for pin #1 of V6. It goes up. The "modern" switch also causes the one power tube to red plate even more if it is on when drive is turned up and volume and master volume are on 20.

[g1]

So what did the 12V reading at pin1 of V4 go to after you changed the tube?
The squeal is probably oscillation which maybe why a power tube is red-plating. Swap the power tubes and see if the red-plate stays with the tube or with the socket.

[ca7922303]

So what did the 12V reading at pin1 of V4 go to after you changed the tube?
The squeal is probably oscillation which maybe why a power tube is red-plating. Swap the power tubes and see if the red-plate stays with the tube or with the socket.

Changed the preamp tube and the 12v reading is gone, replaced power tubes and it stays with the socket.

[ca7922303]

So what did the 12V reading at pin1 of V4 go to after you changed the tube?
The squeal is probably oscillation which maybe why a power tube is red-plating. Swap the power tubes and see if the red-plate stays with the tube or with the socket.

I noticed that channel 2 drive pot was a little loose from all the removing I've done with the boards. Could drive pot loose on channel 2 cause 2 and channel 3 cause the oscillation? Thanks.

[ca7922303]

So what did the 12V reading at pin1 of V4 go to after you changed the tube?
The squeal is probably oscillation which maybe why a power tube is red-plating. Swap the power tubes and see if the red-plate stays with the tube or with the socket.

Red plating stays with socket.

[ca7922303]

Red plating stays with socket.

Correction, both power tube sockets are causing tubes to red plate at full volume drive,/volume/master volume all nearing 10.

[ca7922303]

Correction, both power tube sockets are causing tubes to red plate at full volume drive,/volume/master volume all nearing 10.

Pulled boards and drive pots are not loose like I first thought. Replaced my aster reverb pot(broken). Fx mix now not functioning.

[Jazz P Bass]

Send me the amplifier.
I will fix it!!!

[ca7922303]

So what did the 12V reading at pin1 of V4 go to after you changed the tube?
The squeal is probably oscillation which maybe why a power tube is red-plating. Swap the power tubes and see if the red-plate stays with the tube or with the socket.

Would you be interested in walking me thru the presence pot in relation to oscillation possibly? Thanks.

[ca7922303]

So what did the 12V reading at pin1 of V4 go to after you changed the tube?
The squeal is probably oscillation which maybe why a power tube is red-plating. Swap the power tubes and see if the red-plate stays with the tube or with the socket.

Is it possible that if I switch my OT wires brown and red underneath board, presence control would work and all oscillation would stop and power would increase? I've got brown wire on P14, red on P15. Thanks.