6n11 tube headphone amp

[dobiejoe]

6n11 tube headphone amp. No sound from one side. Both main power chips are 24V and heater amps are putting out 6.9V. Any help would be great. I am thinking the main verable reisiter and I should upgrade all the resisters to 1% metal.
.
The numbers with input being used, no output,
pin 1 200mv with steady rise in MV range only
pin 2, 22MV
pin 3, 200MV
pin 4, 6.9V
pin 5, 36MV
pin 6, 12.06V
pin 7, 20MV
pin 8, 380MV
pin 9, 0V

Any Idea's?

 

[merlin el mago]

6N11 tube is the Chinese equivalent of ECC88 pin 1 & 6 are the anodes/plates so both tubes must have the same voltage so seems don't arrive B+ to pin 1 check the track if there is a burned resistor or the track have a break.

Do you have the schematic?

 

[orion rob]

Bravo 12AU7 Mods and Appreciation thread

 

[merlin el mago]

Bravo 12AU7 Mods and Appreciation thread

I'm not member, I can't see nothing.

 

[dobiejoe]

I replaced all the reisiters with new 1/4W 1% metal film and still no output from the left side. Both heaters work. All amp chips work. I just dont get it. any ideas

 

[merlin el mago]

Have you checked semis: IRF510 & 2N3906?

 

[dobiejoe]

all four power amps work good. 6.7 to the heaters and 24 to the tube.

 

[merlin el mago]

If no signal in one channel inject 1KHz sinus and track with the scope where is lost the signal.

 

[Simon B]

Circuit as shown below?

 

[dobiejoe]

Still no sound out of left side.

Replaced all resisters with 1%
replaced trimmer pots with 2K and tried 10K
both heater amps work and both sides of the tube amps work.

Anything else I need to try?

 

[Stefkorn]

Still no sound out of left side.

Replaced all resisters with 1%
replaced trimmer pots with 2K and tried 10K
both heater amps work and both sides of the tube amps work.

Anything else I need to try?

Check whether the output jack has a faulty connection, check the output capacitor, check the pcb for dry solder joints. As suggested above, a scope will be very useful at this point.

 

[dobiejoe]

anybody?

 

[dobiejoe]

I have no scope and can't throw parts at it all day..

 

[raweseus]

Try turning the device off, and using the ohm meter with probes as a way to check for breaks in the circuit.

With the device on, you can also input signal into it, and simply use multimeter to check for voltage, even with music playing left and right paths should still have approximately same voltage at each corresponding node.

I suggest less of a "replace parts" methodology and more of a investigate what exactly is wrong with it approach.