| ampage Tube Amps / Music Electronics |
For current discussions, please visit Music Electronics Forum. |
ampage archive
Vintage threads from the first ten years
| previous: Giacomo Charles |
 |
|---|
Re: Newbie: hum problem
 3/15/1999 9:09 PM |
|
Bruce | Re: Newbie: hum problem Yes. If you have room, install a 1% to 5% 1 ohm resistor on each cathode in series to chassis ground. If all the resistors measured the same resistance, you will be able to measure the voltage drop across them, respectivly, and determine the aproximate idle current of each tube individualy. If one side of the OT is drawing much more current then the other, then I would first assume one or more power tubes on that side of the OT is going bad. Another thing to consider is the screen resistors. If one screen resistor has failed on one side of the OT, it will effectvly shut that tube down and the opposite OT side's tubes would be drawing more current and unbalancing the OT. That could manifest as a hum too. Does your analog VOM measure milivolts very well? I would be looking for around 28mv to 38mv across each resistor. Bruce |
|---|---|
| Replies: |
| Giacomo Bruce, |