Did a re-cap, amp turned noisy. WTD??

[Jazzprod]

I recently got a 1965 Bandmaster that was all original inside and I felt the urge to re-cap it for safety.

Now that I've done this, it seems it is more noisy(general hum, sensitive to the placement of the guitar around it a.s.o.)

?: Do I need to break the caps in i.e. leave the amp turned on for a day or is there anything else I should think of??

Thanks!

[GUITARmole]

Do you have it back in the cabinet?  If not...THAT could be the cause of some extra noise due to the bottom of the chassis not being shielded.
Also, make sure the new caps are installed correctly (the right polarity) and are the correct value.

[Jazzprod]

Yea I didn't have it in the cabinet when I tested it.... 

I took an advise from an local amp tech and put two 100u/350 instead of the 70u/350's to make it quieter. Still have the proper 20u/450 in though. Is this going to be a problem?

[Jay]

The value shouldn't matter much.  I'd try re-flowing all your solder joints for good measure as well.

[Jazzprod]

The value shouldn't matter much.  I'd try re-flowing all your solder joints for good measure as well.

Pew... 
I thought the value should be an issue...
The amp is back in the cab with re.flowed joints but it's still more sensitive to the guitar (angle) standing in front of it....
 

[GUITARmole]

The amp is back in the cab with re.flowed joints but it's still more sensitive to the guitar (angle) standing in front of it....
 

Could it be that it's just louder with better treble response?    ...seriously!

The values aren't an issue (in fact it's difficult to find the 70uFs).

Also...I just thought of a MAJOR possibility...did you REBIAS after replacing the caps?  If not the bias on your power tubes could be off which definitely could increase hum.

[Infliktor]

Good call on the rebias GuitarMole

[Jazzprod]

Hmm...  I didn't re-bias. Didn't think I had to. Bummer.

A question about the old caps:

As they where dead quiet I've been thinking. When caps get old and bad, how can you tell? Can you hear it or do they just pop?
Is there any indikators you should search for when deciding to make a re-cap?

:-\

[Jazzprod]

Thanks for the reply!

I'm fairly good at soldering and understand the basics of a tube amp. That said, I'm not an expert but has a good knowledge of any electronics and components.

Polarity is ok and so are the instalation of the caps.
I replaced the ones in the "dog bowl" and the 50/50 cap at the rectifier board.

The bias cap is one thing I don't know where it is in the amp? Could you please guide me?

Everything seems fine wire-wise inside the amp and I haven't touched it.
The amp IS quiet when the guitar is NOT plugged in, so.... it's the guitar I guess.

As for one of my initial question, can you tell if the caps are degrading soundwise(pop/hum/noise)? Or do they just short out?

Thanks!

[øøøøøøø]

the bias cap is the one on the little tag board right behind the pilot lamp, over near the power transformer.  It's long-ish and skinny and all by itself.  There will be a series of diodes and a resistor on the board as well.

The "50/50 cap at the rectifier board"  is probably the bias cap, except that it's not the stock value. 

Stock value for the bias cap should be 25uF @ 50V. 

As for your last question, caps can fail in a variety of ways.  They can go short-circuit (popping fuses and breaking things), they can go open-circuit, they can stop filtering (causing hum), they can rupture, explode, develop internal resistance, get quietly hot and explode, lots of stuff.  Some of them are gradual, and most of them are sudden.

[Jazzprod]

Thanks, that's all I need to know.

Really appreciate your help!


Dan

[øøøøøøø]

glad I could help.