JTM45 vs Idiot

Chris-in-LA

Well-Known Member
Joined
Jul 19, 2018
Messages
3,256
Reaction score
3,319
Location
Los Angeles
Finally found the issue!!

I noticed that the tube wasn't heating up as much as the other tubes. The left hand triode finally started conducting when I reflowed the solder on its heater pin. This is despite me testing and re-testing each socket pin with a probe on BOTH top and bottom.

Thanks for all the help and suggestions. Lesson learnt about cold solders!
Yes, sir. Great! I’ve had a few cold solder joints in socket pins and other spots, too. For my builds, that’s usually the issue.
 
Last edited:

william vogel

Well-Known Member
Gold Supporting Member
Joined
Dec 18, 2016
Messages
913
Reaction score
1,108
LOL. No I think the amp won that one. It was on and off the bench for over a month!
From the pictures, I recommend that you melt a good bit more solder into your joints. Do you buy solder by the 1/2 lb or 1 lb roll? If not, buy a roll. And I’m not saying to glob it up, but it’s the purpose of the solder to weld the connections solid. The components on the board are okay but I prefer a little bit more, the wires appear to be “lightly tacked” and this proved to be a problem here and will definitely become a full blown problem as the amp ages.
 

myersbw

Well-Known Member
Joined
Oct 22, 2015
Messages
1,341
Reaction score
849
Location
SW Ohio
I had a Bad Cat Classic Deluxe once. Worked fine...traded it (fortunately to a good friend). He played it and within 10 min the amp cut out. I peeked at it and thought I'd found some oxidation problem causing the issue...sent it back...SAME problem! It came back. All voltages looked good...no failure "on the bench" at any level (was using an external cab). So...I poked every wire with my nylon adjustment tool. FINALLY found the guilty party...and...it pulled right out! (B+ wire!). It was factory oversight...no solder on the wire at all. It had been inserted and bent sideways on the terminal strip solder tab....never soldered. Never had a Bad Cat in before or since with an issue like that. Glad you found the problem!

Also, if you reflow a lot of turrets...as they take a bit of heat, keep an aluminum alligator clip heat sink and clip it on any small signal caps connected to avoid excessive heat. It's just good practice. And, congrats on the fix! :)
 


Top