Bias trimmer pot in 12 series kit, Ground lug need grounded?

harddriver · Post by **harddriver** » Wed Sep 12, 2007 12:30 pm

Hey guys just wanted to clarify this or not, does that third lug on the backside of the trimmer pot need to be grounded?

I can't see underneath in the pics to see it they are or not.

Right now its not connected to anything, I see on the 69 boards they are.

I'm sure this has been asked before so please bear with me.

JimiJames · Post by **JimiJames** » Wed Sep 12, 2007 1:12 pm

JDW3 · Post by **JDW3** » Wed Sep 12, 2007 10:11 pm

JimiJames wrote:

I'm about to add a bias pot to my Traynor, replacing the fixed bias resistor.

In the pic, are there two feeds feeding the bias resistors? Under the board? My amp has both caps tied together at the positive end, fed with one wire.

I want to split them like the pic; just making sure it's possible.

harddriver · Post by **harddriver** » Thu Sep 13, 2007 12:02 pm

It looks like on everything I have seen even with Georges build pics, he uses two legs on the top of the trim pot, which was how I set mine up. Either the two on top or one of the ones on top and the one leg on the bottom.

With any combination one of the legs of the trim pot goes unused/unconnected with the 68 plexi board layout. One the 69 it appears that the ground between the bias filter caps is being connected through that 3rd leg on the back side to ground. The 68 board runs a jumper lead between the turrets.

Thanks for you're replies I just wanted to confirm 100% what I understood to be correct.

white room · Post by **white room** » Fri Sep 14, 2007 8:44 am

It's pretty obvious in the pic where the third lug of the bias pot goes but the caption is saying that the third lug gets tied to the NFB resistor but it should be the bias resistor.

JimiJames · Post by **JimiJames** » Fri Sep 14, 2007 10:54 am

Correct !