Laney TT50H No Outout

[ca7922303]

Yeah, I know that and it can be dealt with later. The HT fuse is blown and it looks like one of the wires that connects to HT spade lug is probably burnt at it's connector. So that lug will need to be resoldered and the connector on the wire may need replacing.

Also see a switch that has been de-soldered in post #232. Which switch is that? Why is it de-soldered?

I didn't know I had main preamp board showing in photo, but that 12 pin piggyback pushbutton switch broke awhile back (xpand/boost switch channel 3) and haven't been able to locate one. Mouser can't get it anymore and the one mfg. that I can find(e-switch) only makes the cap for the buttons now. They gave me a company to try(C-K), but still waiting for a response from them. Any references would be appreciated.

[g1]

This one. I think it's on the preamp board but I noticed it under the midi board in the picture.

[g1]

Ok, back to the midi board then. Cut pin13 of U2 and see if pin13 and 14 pads are still connected (0 ohms).

[ca7922303]

Ok, back to the midi board then. Cut pin13 of U2 and see if pin13 and 14 pads are still connected (0 ohms).

Cut U2 pin #13, now pin#13 to pin#14 reads(117 ohms).
U6 pin#3 pad to ground reads(84ohms).

[g1]

Remove C8 and recheck.

[Enzo]

Just idly thinking, when it wants +3 and -3 for the SS stuff, and the +3 comes up missing, then the -3 just fills the circuit. I think if you fix the +3, that will settle into place.

This is a result of building something for one symptom rather than fixing the existing circuit. The lack of channel switching and the dark preamp tubes is the exact same problem. Your 3v supplies are not happening.

[g1]

looking for the mesa boogie thread?

[ca7922303]

Remove C8 and recheck.

Removed C8 from midi board, U6 pin #3 pad to ground(83.5ohms).

[g1]

Ribbon cable is still disconnected from midi board, yes?
Next try removing C4 from midi board and again check if 83 ohm reading changes.

Make sure midi board is well insulated from touching anything below, use a piece of plastic or cardboard to insulate.

[ca7922303]

Ribbon cable is still disconnected from midi board, yes?
Next try removing C4 from midi board and again check if 83 ohm reading changes.

Make sure midi board is well insulated from touching anything below, use a piece of plastic or cardboard to insulate.

Ribbon cable disconnected, removed C4 from midi board and U6 pin#3 pad to ground (83 ohms).

[g1]

Ground yourself to get rid of any static. Very carefully pry up U4 out of it's socket. A small flathead screwdriver or knife will make it easier. Recheck the 83 ohm reading.

[ca7922303]

Ground yourself to get rid of any static. Very carefully pry up U4 out of it's socket. A small flathead screwdriver or knife will make it easier. Recheck the 83 ohm reading.

Removed U4(14 leg IC-CD4069UBE)-U6 pin#3 pad to ground(83ohms).

[g1]

Ok, put it back in it's socket. Be careful as it's easy to get legs tucked under rather than going into their slots.

Remove R13 and U2 from the board. Be careful not to damage any traces. If it's easier to cut the legs of U2 first, do that. If you have solder wick, you can remove the excess solder first, then lift each leg with a pin while heating with the solder iron.
After removal, clean both areas up with solder wick and/or isopropyl alcohol.

Once it's all cleaned up, check resistance between pin13 and 14 pads. And from pin14 to ground.

[ca7922303]

Ok, put it back in it's socket. Be careful as it's easy to get legs tucked under rather than going into their slots.

Remove R13 and U2 from the board. Be careful not to damage any traces. If it's easier to cut the legs of U2 first, do that. If you have solder wick, you can remove the excess solder first, then lift each leg with a pin while heating with the solder iron.
After removal, clean both areas up with solder wick and/or isopropyl alcohol.

Once it's all cleaned up, check resistance between pin13 and 14 pads. And from pin14 to ground.

Removed R13/U2 R13 pad to R14 pad(10k ohms)
R14 pad to ground(87 ohms)

[ca7922303]

Removed R13/U2 R13 pad to R14 pad(10k ohms)
R14 pad to ground(87 ohms)

[g1]

So the short you had earlier measured between pin13 and14 is gone now. That is good. There must have been a solder bridge between those 2 pins.
Look very carefully (with magnifier) at the solder of the ribbon cable connector and the footswitch connector. See if there are any more solder bridges anywhere.