Laney TT50H No Outout

[g1]

With only ch.3 running, are you able to switch between the 2 master volumes?
First thing to check on the midi board is whether the 7805 regulator (U6) is putting out it's 5VDC.

[ca7922303]

For test purposes you can do a temporary fix so you don't have to flip the board over for now. Then next time you have to remove the board you can resolder that V6 socket.
Run a wire from V5 pin4 to V6 pin4.

Installed wire between pin #4s V5-V6, now have heater ac voltage. Resoldered P20/21, now have output on channel 3, but still no channel switching. Will look back at tests that were run on midi board.

[ca7922303]

For test purposes you can do a temporary fix so you don't have to flip the board over for now. Then next time you have to remove the board you can resolder that V6 socket.
Run a wire from V5 pin4 to V6 pin4.

Thanks for that. I have nightmares about the board. I'll let you know.

[g1]

For test purposes you can do a temporary fix so you don't have to flip the board over for now. Then next time you have to remove the board you can resolder that V6 socket.
Run a wire from V5 pin4 to V6 pin4.

[g1]

Pin #4s V5-V6(7.0vac)

Ok, the problem is in this line. Did you resolder V6 socket on the socket side of the board? The trace is on the socket side. It's a long trace and I think I remember it went under one of the jacks.

[ca7922303]

I guess for the channel switching go back and read through what we checked for that same issue last time around. I'm trying to help, but I don't really have the time to go through the same thing over again?
For the heaters, measure AC volts between pin4 of V5 and pin4 of V6 (one probe to each). Then do same for AC volts between pin9 of V5 and pin9 of V6. If the connections are good, there should be zero volts between. If you find voltage between, there is a break in the connection between the 2 tubes. Follow the trace and look for cracks or burns.

Pin #9s V5-V6(0.0vac)
Pin #4s V5-V6(7.0vac)

I've taken this board out so many times I wonder if I've caused problems along the way, so I'm trying to not take it out again if possible but I see no traces on pin side of board connected #4 pins to V5 & V6.;Looking at schematic, I can't tell if it's possible to do anything without removing board. Any idea from schematic.

[g1]

I guess for the channel switching go back and read through what we checked for that same issue last time around. I'm trying to help, but I don't really have the time to go through the same thing over again?
For the heaters, measure AC volts between pin4 of V5 and pin4 of V6 (one probe to each). Then do same for AC volts between pin9 of V5 and pin9 of V6. If the connections are good, there should be zero volts between. If you find voltage between, there is a break in the connection between the 2 tubes. Follow the trace and look for cracks or burns.

[ca7922303]

The readings are good. The positive regulators have a different pinout than the negative type, that's why the order is different.
Are the heaters still up? You have an intermittent problem with heaters for V1 thru V5. Did you resolder V6 socket? That's where the feed comes from. Resolder V6 socket on component side of board.
The channel lights must also be intermittent if they are sometimes on and sometimes off.

No heaters and channel 3, master volume lights up, but no switching. Have soldered V6. Anything I can take readings on midi board? That was the situation with channel switching before all the work that was done on midi board. Thanks.

[g1]

U1/U2 look good? On top of board(pin side, l took readings in order from right to left. Wondering why the positions aren't lining up with the numbers.

The readings are good. The positive regulators have a different pinout than the negative type, that's why the order is different.
Are the heaters still up? You have an intermittent problem with heaters for V1 thru V5. Did you resolder V6 socket? That's where the feed comes from. Resolder V6 socket on component side of board.
The channel lights must also be intermittent if they are sometimes on and sometimes off.

[ca7922303]

There must be more than one U2. I think you are on the midi board.
These are probably on the main board. The U1 and U2 I mean are 3 pin regulators. One is a 7815 and one is a 7915.

U1/U2 look good? On top of board(pin side, l took readings in order from right to left. Wondering why the positions aren't lining up with the numbers.

[Jazz P Bass]

Send me the amp!!!

[Enzo]

Oh, I can't resist...

400

[ca7922303]

There must be more than one U2. I think you are on the midi board.
These are probably on the main board. The U1 and U2 I mean are 3 pin regulators. One is a 7815 and one is a 7915.

U1(23v/-.7mv/15vdc)
U2(-.8mv/-24v/-15vdc)
For no good reason channel switching lights came on, but will not switch channels and now no heaters. Didn't touch a thing from last readings except mains and standby on/off.

[g1]

There must be more than one U2. I think you are on the midi board.
These are probably on the main board. The U1 and U2 I mean are 3 pin regulators. One is a 7815 and one is a 7915.

[ca7922303]

Check DC volts at all 3 pins of U1 and U2 regulators.

U1(5/0/8vdc), U2 is a 14 pin, which pins to check for DC volts?