Douk EL34 Amp kit

[Avo111]

swapped other input tube into left socket still same left 0 right 35

 

[M Gregg]

swapped other input tube into left socket still same left 0 right 35

Read post 80# again..
We are looking for two input tubes that do not effect the EL34 cathode voltage..

Regards
M. Gregg

 

[Avo111]

tried 2 6h9c in left socket same results

 

[M Gregg]

tried 2 6h9c in left socket same results

What do you mean by same results do you mean the 6h9's don't effect the EL34 cathode voltage?

Regards
M. Gregg

 

[Avo111]

tried input in right socket left el34 10.7 right 0.039

 

[Avo111]

6h9 does same thing on left side pulls el34 to zero. is there a possible screw up in the input wiring that could sink the voltage? the schematic has pins shorted to make valves a single triode.

 

[M Gregg]

tried input in right socket left el34 10.7 right 0.039

OK see what is happening to the voltage on the 10k with and without the input tube. You can test pin 4 EL34 for this!

Are you sure you have 10K correct value..

Regards
M. Gregg

 

[Avo111]

312 with input tube in right socket 335 with input in left socket 308 with no input tubes in either socket

 

[M Gregg]

312 with input tube in right socket 335 with input in left socket 308 with no input tubes in either socket

Measured to ground from pin 4 EL34?

I don't see how the voltage can be lower out of the 10K with no tubes in the input sockets?
The input tubes draw current from the 10K and the voltage drop should increase so the voltage on pin 4 of the EL34 should go down..

Regards
M. Gregg

 

[Avo111]

yes is dropping a bit now 254 left 253 right

 

[M Gregg]

yes is dropping a bit now 254 left 253 right

So as it stands at the moment with both input tubes in what do you have on the EL34 cathodes?

Regards
M. Gregg

 

[Avo111]

pins 2 and 5 on input sockets show 129 left and 128 right. significant noise on left channel speaker when measuring nothing on right speaker without input tubes just putting back in

 

[M Gregg]

pins 2 and 5 on input sockets show 129 left and 128 right. significant noise on left channel speaker when measuring nothing on right speaker without input tubes just putting back in

What voltage do you have on the EL34 cathodes on each channel?
Across the cathode resistor.

Regards
M. Gregg

 

[Avo111]

input valves in, el34 left 7.71 el34 right 0.07
pin 1 and 5 input valve left 156 right 144 crackle on left nothing on right

 

[M Gregg]

input valves in, el34 left 7.71 el34 right 0.07
pin 1 and 5 input valve left 156 right 144 crackle on left nothing on right

Remove the right input tube..what voltage do you get on the cathodes of the EL34's?

Regards
M. Gregg

 

[Avo111]

left 10.69 right 11.75

 

[Avo111]

i have to go take girlfriend to movies (Steve Jobs) she's getting grumpy :0
thanks for this help any more ideas I will check out tomorrow

thanks again!

 

[M Gregg]

left 10.69 right 11.75

OK looks like the right input tube is pulling down the G2 supply. try another tube in the right input..what values do you have on the EL34 cathode resistors?

Check all resistor values on the right input tube..and all connections.

Regards
M. Gregg

 

[M Gregg]

OK.

Regards
M. Gregg

 

[celestar32]

Remove the right input tube..what voltage do you get on the cathodes of the EL34's?

Regards
M. Gregg

Hi Gregg, do you think that is possibility of dry solder job was causing the problem? Anyway it is great to see you helping to solve the issues. Cheers!