Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Jomamma on July 25, 2014, 09:50:10 am

Title: Biasing a (I think 1983) Fender Concert
Post by: Jomamma on July 25, 2014, 09:50:10 am

Using an old style amp probe. One that plugs into a multimeter set on DCA, 200m.  The max reading can get is about 9.  (6L6 power tubes) The information I have says around 35ma is where it should be.  What's going on?

Thanks
Jomamma

Title: Re: Biasing a (I think 1983) Fender Concert
Post by: sluckey on July 25, 2014, 11:03:54 am

Tell us more about your bias probe. What does it look like? How does it connect to the amp? Which meter do you have?

Title: Re: Biasing a (I think 1983) Fender Concert
Post by: SILVERGUN on July 25, 2014, 01:22:04 pm

Our 'old style' clamp on amp probe sounds similar to yours....
10 out of 10 guys that go to use it for the first time set the meter to read mA and can't figure out why it doesn't read right...
Got me the first time too  :icon_biggrin:

Problem is,,,it puts out a milli-VOLT signal that you read by setting the meter to the mV range.

Try that

Title: Re: Biasing a (I think 1983) Fender Concert
Post by: Jomamma on July 25, 2014, 07:16:08 pm

Way to go Silvergun, I had my meter on the wrong setting.

Thank You
Jomamma