Laney TT50H No Outout

[ca7922303]

Why not do them both at the same time? = no result!?! Wait? has this already happened?

Green and blue grid wires were swapped which stopped all the oscillation except for when either xpand or boost switches are engaged. Was wondering about swapping bias (both orange) or HT(both red) ?

[Chuck H]

Switching the OT wires would do the same thing as changing the grid wires back to where they were, so no point in doing that.
They are different methods of achieving the same result.

Why not do them both at the same time? = no result!?! Wait? has this already happened?

[g1]

Switching the OT wires would do the same thing as changing the grid wires back to where they were, so no point in doing that.
They are different methods of achieving the same result.

[ca7922303]

It's likely that the oscillation is robbing the power and also causing the red-plating.
Reversed OT phase usually makes the presence work in reverse, so I don't think that will make the presence work. But check if turning up the presence makes things better (reduces oscillation). If so, yes the OT wiring is reversed.

I'm not sure what changes have been made as suggested by catalin in the other thread so I can't really comment. Have you dug through all your pictures to see if any of the wiring colors have been changed?

Presence control has no effect on the oscillation I also see that damper/tight switch is also not doing anything. Checked schematic and they are connected. Checked for resistance on pins 10,9, & 3 on d1,D2, & d3 ribbon cables and they're all good. Schematic shows that OT wires are correct compared to photos of underside of board. Brown wire is 4 ohm, red is 8 ohm, orange is 16 ohm, black is ground. Am I ok switching the OT wires as far as daany damage to board or transformers? Only change that was made on other post is green and blue grid wires were swapped, which eliminated most of oscillation, except for when xpand or boost is engaged. Thanks for your help.

[g1]

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.

It's likely that the oscillation is robbing the power and also causing the red-plating.
Reversed OT phase usually makes the presence work in reverse, so I don't think that will make the presence work. But check if turning up the presence makes things better (reduces oscillation). If so, yes the OT wiring is reversed.

I'm not sure what changes have been made as suggested by catalin in the other thread so I can't really comment. Have you dug through all your pictures to see if any of the wiring colors have been changed?

[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.

[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.

[Jazz P Bass]

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

[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.

[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]

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]

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.

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

[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]

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.