Biasing the 20thA XTC

[Ventura]

Not trying to put the cart before the horse here, folks... But as some of you know, I'm getting close to picking one of these puppies up, and wanted to know - if I want to swap out the valves in the future for whatever reason (they die, they need replacing, I want to try other tubes, yada yada) is the re-bias easy? Is there an external pot? External DMM contact points?

THANKS!!
V.

 

[Ventura]

Is this like, some kinda ridiculously LAMO question or am I off my rocker asking it or something ???

V.

 

[RedB4Black]

I'd imagine it's like the 101B. pretty easy to bias if you have a weber bias-rite

 

[Ventura]

I'd imagine it's like the 101B. pretty easy to bias if you have a weber bias-rite

Actually I happen to have one that just recently showed up to my door... My question is, where's the trim pot? Is it an external bias point or does it mandate chassis removal, etc...

Anyone??

Thanks,
V.

 

[romvert]

I believe none of the Bogners have external points. You'd have to remove the chassis. Assuming the topography is similar to my 101b, looking from the back of it, you'll fing the trim pot on the left corner closest to you, near the bias resistor.

 

[Death by Uberschall]

I believe none of the Bogners have external points. You'd have to remove the chassis. Assuming the topography is similar to my 101b, looking from the back of it, you'll fing the trim pot on the left corner closest to you, near the bias resistor.

Rev. Blue Uberschalls have external bias points and adjustment

 

[Ventura]

I believe none of the Bogners have external points. You'd have to remove the chassis. Assuming the topography is similar to my 101b, looking from the back of it, you'll fing the trim pot on the left corner closest to you, near the bias resistor.

Got a pic?

Thanks,
V.

 

[romvert]

I believe none of the Bogners have external points. You'd have to remove the chassis. Assuming the topography is similar to my 101b, looking from the back of it, you'll fing the trim pot on the left corner closest to you, near the bias resistor.

Rev. Blue Uberschalls have external bias points and adjustment

Thanks for the correction. Apparently nobody owns a 20th here...

 

[romvert]

I believe none of the Bogners have external points. You'd have to remove the chassis. Assuming the topography is similar to my 101b, looking from the back of it, you'll fing the trim pot on the left corner closest to you, near the bias resistor.

Got a pic?

Thanks,
V.

Unfortunately I don't but you could find one if you search the Bogner forum. And that would probably be a 101b, not a 20th, since they're fairly new and all...

 

[rockridge98]

Thanks for the correction. Apparently nobody owns a 20th here...

I'm looking at the back of a 20th Anniv right now and there is no external bias trim that I can see.

 

[Ventura]

Thanks for the correction. Apparently nobody owns a 20th here...

I'm looking at the back of a 20th Anniv right now and there is no external bias trim that I can see.

Have ya ever re-biased that puppy since owning it?

V.

 

[RedB4Black]

It'll be an internal bias pot. Probably somewhere close to the underside of the power tubes. the pot will probably be white, plastic and have an arrow shaped hole in the middle. Stick a small screw driver in the arrow hole and turn to adjust the bias. Use a weber bias-rite to determine the bias level.

 

[Ventura]

It'll be an internal bias pot. Probably somewhere close to the underside of the power tubes. the pot will probably be white, plastic and have an arrow shaped hole in the middle. Stick a small screw driver in the arrow hole and turn to adjust the bias. Use a weber bias-rite to determine the bias level.

Oh hell, I know what they look like, it's just sometimes it's easy to confuse the hum trim pot with the biasing pot - that is, if indeed the 20thA comes equipped with a hum trim pot...

Nevertheless, just thought I'd ask. And ya, after my umpteenth time doing shunt method biasing on my Diezel(s), I decided to get the Weber unit... Just seems to me a lot cleaner to work with.

Peace,
V.