Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Lambertini on March 12, 2024, 05:36:24 am

Title: Best way to A/B tests coupling capacitors?
Post by: Lambertini on March 12, 2024, 05:36:24 am

Hello!

I'm building a new AB763 from scratch. I have several options for coupling capacitors I'd like to A/B tests.

Is there a good practice / best way to do these comparisons without too much soldering/desoldering work that would mess up the eyelet board, the solder joints and the capacitors themselves?

I know some sockets exist for mounting transistors on effects pedal PCB. Is there something similar for eyeletboards?

Is there any other "neat" way to do these tests before final soldering?

Thanks!

Title: Re: Best way to A/B tests coupling capacitors?
Post by: sluckey on March 12, 2024, 05:41:54 am

Gator clip test leads are your friend.

https://www.amazon.com/WGGE-WG-026-Pieces-Colors-Alligator/dp/B06XX25HFX/

Title: Re: Best way to A/B tests coupling capacitors?
Post by: Lambertini on March 12, 2024, 05:49:27 am

Quote from: sluckey on March 12, 2024, 05:41:54 am

Gator clip test leads are your friend.

Thank you sluckey. I have some, maybe not enough. But how would you use them?

Second thought, I think I get it. I would simply clip them to the previous / next component leads, right?

Title: Re: Best way to A/B tests coupling capacitors?
Post by: sluckey on March 12, 2024, 06:19:19 am

You only need two test leads. Remove the cap from the board. Connect the two test leads to the board eyelets that the removed cap was soldered to. Now connect the test cap to the free ends of the test leads.

Title: Re: Best way to A/B tests coupling capacitors?
Post by: Lambertini on March 12, 2024, 06:30:14 am

Nothing is connected / soldered at that time. Fresh eyeletboard, fresh resistors, fresh caps, fresh everything.

I'll need more alligator clips as I have several full sets of coupling caps to A/B tests: vintage caps from a silferface twin, Sozo Blue, Jupiter Red and Orange Drop.

In the past months I've delt with existing builts with already soldered components, each time you twist the component lugs, solder / unsolder things, you mess them up a bit at a time (wires, lugs, eyelets...). I'm in a sort of "breadboard" phase before doing the actual job.

When I see your circuits, they are so neat and clean I doubt you solder / unsolder things, rather do things "good at first time" ^^

Anyway I think I get it: solder everything except the caps, leave the caps eyelets empty, then use alligator clips to connected the cap set to the previous / next components in the best way for each one. I'll figure out the method completely when I'll be at the "doing" stage.

Title: Re: Best way to A/B tests coupling capacitors?
Post by: PRR on March 12, 2024, 05:49:12 pm

I always tinned the lug, tinned the lead, then tapped the soldering iron on it to "tack solder". It will hold in the house, though not on the bad road to Holden mountain where you need mechanical wrap.

Long clip-leads make guitar amps squeal. Sometimes you can route out of trouble, maybe. It also IMHO encourages "live" changes, and I do that on 24V transistor stuff, but I gotta stop reaching my sweaty hands into 350V gear (actually I stopped in 1989, for good reason).