Please help! High Voltage on 1,A8, A6, and B1 and A8 led not working

[davidvanderbilt]

Just completed my bottlehead crack and tested resistance and voltage. Everything checks out besides the LED to A8 not working and the voltage readings as follows: tested (expected):

1: 152 (90)
A6: 152 (90)
B1: 152 (90)
A8: 12 (1.5)

All of the other voltages are okay and I re-soldered all the connections through this circuit including the centerpin on the A tube connection. After reading another thread on this forum with high voltages, I double checked to make sure the centerpin on the A tube was properly grounded and resoldered it twice, but it didn't help.



The amp actually works too and sounds good. Any help would be greatly appreciated!!
 

[Paul Birkeland]

All your voltages stem from that LED not lighting and/or no current being drawn in that region.

The last instance of this exact set of circumstances occurred because the white wire leaving the volume pot and connecting to A7 was not properly attached.  Can you check on this?

-PB

[davidvanderbilt]

All your voltages stem from that LED not lighting and/or no current being drawn in that region.

The last instance of this exact set of circumstances occurred because the white wire leaving the volume pot and connecting to A7 was not properly attached.  Can you check on this?

-PB

Thanks for your response!! Sure let me check on this really fast. Just to be 100% clear the wire I have going from the volume pot going to A7 is red, I'm assuming this is still the same wire you are referring to?

Thanks!

[davidvanderbilt]

I checked and resoldered A7 and where it attaches to the volume pot but the LED is still not lighting up

[Grainger49]

Often times when one half of a tube doesn't work it is in the cathode circuit.  The circuit for A8 is simply the LED.  And the LED looks to have the proper orientation.

Try using your meter set on the lowest resistance range you have.  Place the red lead on A8 and the black lead on the center pin of the tube socket.  I.E. across the LED with the red on the cathode (A8).  Many meters will light an LED.  If it doesn't light try the red lead on A3.  We know that this LED is working.  If this one doesn't light the meter doesn't supply enough voltage.

It is worth a try and you don't have to remove anything.

[davidvanderbilt]

Often times when one half of a tube doesn't work it is in the cathode circuit.  The circuit for A8 is simply the LED.  And the LED looks to have the proper orientation.

Try using your meter set on the lowest resistance range you have.  Place the red lead on A8 and the black lead on the center pin of the tube socket.  I.E. across the LED with the red on the cathode (A8).  Many meters will light an LED.  If it doesn't light try the red lead on A3.  We know that this LED is working.  If this one doesn't light the meter doesn't supply enough voltage.

It is worth a try and you don't have to remove anything.

Thanks for your response! You are completely right, I tested the LED i know is working and it lit up correctly using my multimeter, however the led attached to A8 DID NOT light up. I am assuming this is a bad LED correct?

Thanks again!

[Grainger49]

Yup, Contact Bottlehead and they will send a replacement.

[davidvanderbilt]

Awesome, thanks so much for your guys help!!