Laney TT50H No Outout

[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]

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]

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.

[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?

[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) ?

[g1]

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.

I've got brown wire on P14, red on P15. Thanks.

Your two statements do not agree. Look at pg.10 of schematic, below spkr. jacks. P14 is 8 ohm, P15 is 4 ohm. So if red is 8, it should go to P14.

You can ignore what I said in post #364, I thought you were talking about reversing the OT wires that go to power tube plates.

Fix the amplifier faults. Focus on the presence control and damper switch as they are problems that can cause oscillation. Do not get distracted chasing oscillation, it is a symptom, not the cause. And please do not create other threads about the same amp, it just confuses everyone.

[ca7922303]

Your two statements do not agree. Look at pg.10 of schematic, below spkr. jacks. P14 is 8 ohm, P15 is 4 ohm. So if red is 8, it should go to P14.

You can ignore what I said in post #364, I thought you were talking about reversing the OT wires that go to power tube plates.

Fix the amplifier faults. Focus on the presence control and damper switch as they are problems that can cause oscillation. Do not get distracted chasing oscillation, it is a symptom, not the cause. And please do not create other threads about the same amp, it just confuses everyone.

Thanks, I will swap those tonight after work. Got inpatient, trying to force the issue is reason for other posts. Appreciate the help again.

[ca7922303]

Your two statements do not agree. Look at pg.10 of schematic, below spkr. jacks. P14 is 8 ohm, P15 is 4 ohm. So if red is 8, it should go to P14.

You can ignore what I said in post #364, I thought you were talking about reversing the OT wires that go to power tube plates.

Fix the amplifier faults. Focus on the presence control and damper switch as they are problems that can cause oscillation. Do not get distracted chasing oscillation, it is a symptom, not the cause. And please do not create other threads about the same amp, it just confuses everyone.

Odd thing, on board P14 is 4 ohms, P15 is 8 ohms. Swapped red and brown lead, now red is plugged into 4 ohms, brown is plugged into 8 ohms and there is no output at all?

[Enzo]

And the black wire that is not connected goes to???

[ca7922303]

And the black wire that is not connected goes to???

P16(ground)

[Chuck H]

As yet unaddressed it seems (?)... There seems to be some sort of trouble here.

[g1]

Odd thing, on board P14 is 4 ohms, P15 is 8 ohms. Swapped red and brown lead, now red is plugged into 4 ohms, brown is plugged into 8 ohms and there is no output at all?

Ok, if the board is labelled, then there must be an error on the schematic where they have p14 and p15 shown wrong. Put red to 8ohm lug and brown to 4 ohm lug.
Like Enzo said, if the black was disconnected there will be no output.

Also agree with what Chuck H mentioned, it looks like there has been a spill or there is a lot of flux residue all over the board. Such residue can cause problems and should be cleaned up. An old toothbrush and some rubbing alchohol (isopropyl) will usually do the job.

[ca7922303]

Ok, if the board is labelled, then there must be an error on the schematic where they have p14 and p15 shown wrong. Put red to 8ohm lug and brown to 4 ohm lug.
Like Enzo said, if the black was disconnected there will be no output.

Also agree with what Chuck H mentioned, it looks like there has been a spill or there is a lot of flux residue all over the board. Such residue can cause problems and should be cleaned up. An old toothbrush and some rubbing alchohol (isopropyl) will usually do the job.

Those are old photos when I first took it apart to see how to reattach wires. Residue has since been cleaned off. V1-V5 now has no heaters. AC voltage is 0.0. V6 is (7vac) R43 is (449/433vdc). V1-V5 pins 1 & 6(448/448vdc). V6 pins 1 & 6(287/280vdc)R52(0/0vdc)hum balance pot(0/0/0vdc).

[Enzo]

Ah geez...

V1-V5 now has no heaters

You have to have tube heaters lit. All the speaker lines, impedance selectors, B+ voltages, biases and everything else, NONE of that matters if your tube heaters are not running. Get all the tube heaters running on all the tubes before worrying with ANYTHING else. When your tube heaters are off, then we already expect the B+ on the plate pins will go real high. That is how amps work. And when that happens, the cathode voltages also drop to zero. But that is irrelevant. The heaters are off and so the tubes don't conduct.

[Chuck H]

In post #21 of your grid stopper thread I discouraged you from messing with the orange and white wires on V6 in the photo below. Did you mess with them anyway? This is your filament circuit.