Laney TT50H No Outout

[ca7922303]

So when you put signal into FX return, do you get sound at the speaker? That tells you whether the power amp section is working or not.
To test the preamp, you put signal into the guitar input and see if there is signal at the line out. (you would need to send line out signal to another amp)

Signal into guitar input, line out to another amp. No signal. But I could here signal when turning power off on Laney amp.

[ca7922303]

FX return is an input, line out is an output. When you put signal to FX return you get sound at the output?

Odd thing I believe. Line out and record out will send signal to other amp when signal is run thru efx return. Line out will produce signal when signal is run thru line out and to a speaker. It is a much lower signal and volume controls have no effect on it.

[ca7922303]

Odd thing I believe. Line out and record out will send signal to other amp when signal is run thru efx return. Line out will produce signal when signal is run thru line out and to a speaker. It is a much lower signal and volume controls have no effect on it.

And signal cuts off when standby is turned off. When running signal thru fx send, signal is produced with or without standby switch on.

[g1]

Check DC volts on both sides of that 4K7 resistor you replaced, R43 (in play mode).

[ca7922303]

Check DC volts on both sides of that 4K7 resistor you replaced, R43 (in play mode).

R43(442/370vdc)

[g1]

Ok, check DC on pins 1 and 6 of each preamp tube.

[ca7922303]

Ok, check DC on pins 1 and 6 of each preamp tube.

Checked R43 again, now (447/429 vdc)
hum balance (16/16vdc)
V1(#1-425/#6-424vdc)
V2(#1-427/#6-425vdc)
V3(#1-431/#6-425vdc)
V4(#1-425/#6-424vdc)
V5(#1-429/#6-425vdc)
V6(#1-286/#6-265vdc)

[g1]

Can you see that the tubes V1 thru V5 are lit up? It's like they are not running. Thats why the voltage has jumped up from 370 to 429V at R43.
I would expect either they are not lit up, or there is a main preamp ground not connected somewhere (or burnt ground trace).

[ca7922303]

Can you see that the tubes V1 thru V5 are lit up? It's like they are not running. Thats why the voltage has jumped up from 370 to 429V at R43.
I would expect either they are not lit up, or there is a main preamp ground not connected somewhere (or burnt ground trace).

V1-V5 are not lit. V6 is lit but not warm. Also, channel switching will not switch out of channel 3, never has since I started working on this.

[g1]

V1-V5 are not lit. V6 is lit but not warm

Well this would have occurred very recently, something in the heater circuit got disconnected or burnt. When you had the 370V at one end of R43 they will have been lit up.
There should be 6VAC between pin4 and 9 of each preamp tube. It sounds like you have it at V6 but not V1 thru 5.

[ca7922303]

Well this would have occurred very recently, something in the heater circuit got disconnected or burnt. When you had the 370V at one end of R43 they will have been lit up.
There should be 6VAC between pin4 and 9 of each preamp tube. It sounds like you have it at V6 but not V1 thru 5.

V1-V5 between pins 4 & 9 is .02 vac V6 between pins 4 & 9 is 7.3 vac
Don't see anything obvious on installed board. Can you give me a way to locate what is going on here? Thanks.

[g1]

Follow the traces from pin9 and pin4/5 on V6. They will go to V5 or maybe one of the other preamp tubes. Look for any burns, or problems with the repair/jumper at V5 socket. Check or resolder all pins 4,5, & 9 at preamp sockets.
Aside from visual inspection, use your meter on resistance setting.

[ca7922303]

Follow the traces from pin9 and pin4/5 on V6. They will go to V5 or maybe one of the other preamp tubes. Look for any burns, or problems with the repair/jumper at V5 socket. Check or resolder all pins 4,5, & 9 at preamp sockets.
Aside from visual inspection, use your meter on resistance setting.

Getting 0.0 ohms V6 pin#9 to V1-V5 pin#9s, getting 0.8 ohms V6 pin#4/5 to V1-V5 pin#4/5.resoldered some pins, no change.

[The Dude]

It will be difficult to use continuity tests to find the fault, unless you remove the tubes and unhook the filament transformer leads, because those are basically pieces of wire that you are reading across. It's better to use voltage measurements. My best guess is that when you removed the V5 socket, you destroyed a feed through on one or more of the PCB holes. Try soldering the socket side of V5 to be sure that connections are getting from one side of the board to the other. Then see if the other tubes light.

[ca7922303]

Full power R43(435vdc)
v1(#1-262vdc/#6-289vdc)
v2(#1-371vdc/296vdc)
v3(#1-435vdc/241vdc)
v4(#1-373vdc/303vdc)
v5(#1-435vdc/239vdc)
v6(#1-293vdc/282vdc)

R52(0.00vdc/0.00vdc)
Hum balance pot (12vdc/12vdc)

These are the readings I got before replacing R43 with correct 4.7k ohm resistor, all preamp tubes were lit. Now after replacing R43, V1-V5 are not lit. Am New R43 still reads 4.7 k ohms in circuit and I'm getting 400+ vdc on both ends of R43. Will double check all the wiring underneath board again. Any, will solder all pins on tube side of V5. Any other thoughts while I have the board disconnected again? Thanks for all the help.