How to match pinout for trim pots?

[62vauxhall]

Hoping for some enlightenment.

If the distance between pins on trim pot data sheets exists, I cannot comprehend it. Other than being 1K ohm and 1/4 watt, I am at a loss to pick one.

I removed an original that is suspect so as I could measure distances between pins but so far, I cannot see that specification quoted for new replacements.

FWIW, the distance between the center of the two outside pins is .277" or 7.04mm.

 

[62vauxhall]

The original that I removed has a width of 11mm so I chose two types based on that dimension. I was focusing on 12 turn top adjustment so settled on one that is 6.35mm X 4.19mm. When in front of me, I will see if it can be made to fit.

I looked as well at single turn type and ordered that type too which is 10mm in size. It might prove to be an easier fit.

The one I removed is for DC bias adjust and I think the act of turning it caused a short somewhere that blew fuses. All was good before I tried lowering the bias by 20mv - DBT went dark after switching on power. But after moving that trimmer pot, DBT stayed bright.

 

[grapplesaw]

This is typical wiring for bias Gary

 

[62vauxhall]

Thanks Glen, that will help. Those I ordered should arrive in 3 or 4 days.

Next chore for me I guess is pulling the output transistors and see if any of those got damaged.

 

[62vauxhall]

Two of the four output transistors were gone and are now replaced. When I receive and install new bias pots, the DBT will hopefully go dark.

Assuming that both the 12 turn pot and single turn pot I ordered can be made to fit, is one better than the other for bias adjutment in a SS amp?

My assumption was that since a 12 turn allowed more precise adjustment, that it would be preferred but yesterday I read somehwere that a single turn pot was better suited for that purpose.

 

[grapplesaw]

Two of the four output transistors were gone and are now replaced. When I receive and install new bias pots, the DBT will hopefully go dark.

Assuming that both the 12 turn pot and single turn pot I ordered can be made to fit, is one better than the other for bias adjutment in a SS amp?

My assumption was that since a 12 turn allowed more precise adjustment, that it would be preferred but yesterday I read somehwere that a single turn pot was better suited for that purpose.

That’s it Gary
One turn is all we use in the PL but if required the multi turn is more accurate

I’d try the single turn first I guess

 

[J!m]

Number of turns is inversely proportional to the number of cups of coffee you’ve had.