Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: pbman1953 on August 25, 2023, 05:45:39 pm

Title: Which resistor would you keep?
Post by: pbman1953 on August 25, 2023, 05:45:39 pm

I'm thinking of replacing some older parts in an Acoustic 370 amp (1971)amp. Never worked on


I have 4 carbon comp's in the whole amp-


The 22 ohm 2 w measures- 23.8


The 10 Ohm 2w measures- 10.9


The 56k measures - 59.7


The 270k measures 297k. I have new 270's that measure out of the package at 243k


Would keep the ones that are close to the original or replace them due to age.


Thanks

Title: Re: Which resistor would you keep?
Post by: Dave on August 25, 2023, 05:57:49 pm

If the amp sounds good and doesn't exhibit any problems, I wouldn't touch a thing.


Dave

Title: Re: Which resistor would you keep?
Post by: pbman1953 on August 25, 2023, 06:14:34 pm

Thanks Dave!


I'll leave those as is but there are small electrolytics that are bulging on the end's. I'll probably update them

Title: Re: Which resistor would you keep?
Post by: pbman1953 on August 27, 2023, 10:31:21 am

Ok, so I left the resistors because they were still in spec but I figured to replace the caps just because they're old. I installed all new caps and the amp came up fine but seem to lose volume after a minute. Meanwhile while the old parts were out I tested them again an they seamed to be ok. Feeling something was wrong with the new parts I put the old ones back and the same thing happened.


Thanks for any help

Title: Re: Which resistor would you keep?
Post by: HotBluePlates on August 27, 2023, 06:39:26 pm

Quote from: pbman1953 on August 27, 2023, 10:31:21 am

... I installed all new caps and the amp came up fine but seem to lose volume after a minute. ... Feeling something was wrong with the new parts ...

"Lose volume" sounds like a loose connection somewhere.

I first thought that maybe you had a poor connection with one of the new car, until you said you had the same symptom after putting the old parts back in.  So unless you made some not-great wiring both times, look to loose jack or socket contacts, or a broken resistor.

Title: Re: Which resistor would you keep?
Post by: pbman1953 on August 28, 2023, 07:36:57 am

I found it with a chop stick. One cap i didn't change had a bad connection. It's leg was iffy.


I'll get a new one.




Thanks!