Laney TT50H No Outout

[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.

[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.

[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.

[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.

[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]

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.

Unable to switch between master volumes and U6 reads(8/0/5vdc). Thanks

[g1]

I think U2 on midi board was replaced? Have a look with a magnifier at all the solder connections. Also look at solder on ribbon cable connector and make sure the cable plugs are well seated at both ends.
If nothing obvious, measure DC volts at U2 pin2 and again while pressing ch.1 switch.

[ca7922303]

U2 was replaced, solder connections on it and ribbon cable socket look good. U2 pin #2(0.8vdc), pressing channel one(1)(0.3mvdc).

[g1]

So in post #412 you have 5V coming out of the 7805 regulator, is solder good at that pin on both sides of board?
The 5V should get to U2 pin14, is it there? If not, follow the trace back to the 7805 regulator and find why it is not getting the connection.

[ca7922303]

So in post #412 you have 5V coming out of the 7805 regulator, is solder good at that pin on both sides of board?
The 5V should get to U2 pin14, is it there? If not, follow the trace back to the 7805 regulator and find why it is not getting the connection.

U2 pin #14(5V). Solder is good on both sides of 7805 regulator. Now when I power on, channel 2 lights up only, can switch between both master volumes and have output(channel 2 only).

[g1]

So something in the process of looking at those connections and checking that voltage made the master vol. switching and the Ch.2 light work.
Some kind of intermittent connection. Flex the midi board and prod the connectors to see if you can make the lights go on and off.

[ca7922303]

So something in the process of looking at those connections and checking that voltage made the master vol. switching and the Ch.2 light work.
Some kind of intermittent connection. Flex the midi board and prod the connectors to see if you can make the lights go on and off.

Channel 3 will light up when pushed, but goes back to channel 2 when released. Flexed board and prided U2 pins, no change. Noticed that all pins on U2, with the exception of 5,6,7 are 5 volts. 5,6,7 are millivolts.

[ca7922303]

Channel 3 will light up when pushed, but goes back to channel 2 when released. Flexed board and prided U2 pins, no change. Noticed that all pins on U2, with the exception of 5,6,7 are 5 volts. 5,6,7 are millivolts.

Channel 3 does also have output when pushing button in, but cuts out when released and goes back to channel 2 lighting up and has output.

[g1]

Is channel 2 button stuck down? It must release.
Look at pg.11 of schematic. Pin5 of U2 goes to R3. Check that R3 is 10K. Check that R3 is getting it's 5V at one end.
If R3 is ok and getting 5V, then pin5 of U2 should be 5V except when ch.2 button is being pressed. If it's not stuck down it could be a bad switch, or something in that line from the switch to U2 pin5 could be getting shorted to ground.

[ca7922303]

Channel 2 is not stuck, R3 is (0.5k ohms)and is getting (5v) at one end. Pin Uncategorized Groups of U2 is (5.6mv) lit up and (1.3mv) when pushed in.