Forte Model 1 and Forte Model 3 Adjust Bias

[EddieRock]

I've read a few posts here about adjusting the Bias and I'm a bit confused on which resistors are the emitter resistors. I've attached a pic of the board. Can someone point out which is the emitter resistors and which posts I should get the meter readings from when adjusting?

See attached image. Ultimately, an arrow to the component would be helpful 🙂

Also, there is talk about replacing the pot for a 20 turn and this board has one I believe. Can someone send me a link to the correct POT to purchase? I've got a Forte Model 3 and a Forte Model 1 that I'm getting up and running.

thanks for all you do!

 

[llwhtt]

The right leg of the big transistors are the emitters and connected to each emitter is a big gray resistor, that's the emitter resistor. Put one DMM lead on one end and the other lead on the other end. Use mini-grabbers or clips if you have them. The left leg is the base and the middle leg is the collector.

Craig

 

[EddieRock]

So, what your's saying is measure where the two arrows point in the pic below?

Also, do I have to measure the reading on all or is just one good enough?

Thanks!

 

[Chamberman]

Yes measure where the two arrows are pointing.

Just measure across the one resistor. The other resistors are assumed to be the same.

 

[EddieRock]

This was very helpful. The Forte Model 1 is running now around 48 degrees Celsius. Sounds FANTASTIC!

Please note, the emitter resistors varied in millamps around 68mV to 75mV when at 48 Celsius. Is that a concern that there is a wide range?

If so, what should I be looking at to see if there is another component I should determine if it is failing. Or is that just the +/- of the component tolerances?

thanks!

 

[Nelson Pass]

No, that's fine. 10% tolerance is pretty good.

 

[EddieRock]

Thank you Mr. Pass!

I absolutely love these amplifiers (own a Forte Model 3 and Model 1).

I'm so happy that you actually replied! Bucket list (not really but awesome)

back to you!!