Laney TT50H No Outout

[ca7922303]

That's on the variac? Sounds good so far. If going up with the variac and the reading on the hum balance pot stays in the mV rather than volts, you should be ok I think.

Previous readings were without tubes. Now with all tubes in, full power(no Variac), 442vdc @ R43, 13vdc @ hum balance both pins. I'm able to get a signal thru efx return and line out only. No preamp controls.

[g1]

That seems kind of high at R43. Caps at either end of it show 400V rating, so be careful. Suggest using variac and not exceeding 400V there. What is the voltage at it's other end? Are all preamp tubes lit up?

What is the DC voltage at either end of the resistor going to the hum pot, R52 ?

[ca7922303]

That seems kind of high at R43. Caps at either end of it show 400V rating, so be careful. Suggest using variac and not exceeding 400V there. What is the voltage at it's other end? Are all preamp tubes lit up?

What is the DC voltage at either end of the resistor going to the hum pot, R52 ?

With Variac and all tubes installed, R43 @400vdc, R52(0.0mv/0.0mv), and hum balance pot is about 5vdc both pins.

[ca7922303]

That seems kind of high at R43. Caps at either end of it show 400V rating, so be careful. Suggest using variac and not exceeding 400V there. What is the voltage at it's other end? Are all preamp tubes lit up?

What is the DC voltage at either end of the resistor going to the hum pot, R52 ?

Also R52 reads 98.3 ohms resistance

[g1]

What is voltage at both ends of R43 ? Are all preamp tubes lit up?

[ca7922303]

What is voltage at both ends of R43 ? Are all preamp tubes lit up?

All preamp tubes are lit and R43 with Variac on is 400vdc/392vdc.

[g1]

Are you up to full voltage on the variac yet, or still at reduced line voltage?
Measure DC volts at all preamp tubes pins 1 and 6 and post your results.

[ca7922303]

Are you up to full voltage on the variac yet, or still at reduced line voltage?
Measure DC volts at all preamp tubes pins 1 and 6 and post your results.

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)

[g1]

What does the resistance of R43 read?

[g1]

There are 2 versions of the amp in the schematic package. I may have been looking at the wrong one. Although 8V across R43 seems wrong in any case.
Are C37 and C23 in your amp 400V rated, or 450V ?

[ca7922303]

What does the resistance of R43 read?

R43(0.453k ohms) resistance

[ca7922303]

There are 2 versions of the amp in the schematic package. I may have been looking at the wrong one. Although 8V across R43 seems wrong in any case.
Are C37 and C23 in your amp 400V rated, or 450V ?

With board back in, only one I can read is C2 and it shows 450v. If that doesn't help, let me know and I'll pull the board again.

[ca7922303]

There are 2 versions of the amp in the schematic package. I may have been looking at the wrong one. Although 8V across R43 seems wrong in any case.
Are C37 and C23 in your amp 400V rated, or 450V ?

I can see C22(450v) also.

[g1]

R43(0.453k ohms) resistance

I think that is 470 ohms. It is supposed to be 4.7K ohms. That is why the voltage drop across it is only 8V. So it needs to be changed.
Other than that, if it has the higher voltage rated caps, like the later revision schematic shows, those 435V readings are not a problem. The high voltage at the hum pot is no longer there so I'm sure it is not smoking anymore.
Change that resistor to the proper value and you should be good to do sound test.

[ca7922303]

I think that is 470 ohms. It is supposed to be 4.7K ohms. That is why the voltage drop across it is only 8V. So it needs to be changed.
Other than that, if it has the higher voltage rated caps, like the later revision schematic shows, those 435V readings are not a problem. The high voltage at the hum pot is no longer there so I'm sure it is not smoking anymore.
Change that resistor to the proper value and you should be good to do sound test.

Had two(2) new extra resistors for R43. Used two(2) different dmm's.