Help with my tweed Champ

[Dogbreath]

I hope some of you can help me with a perplexing problem with my tweed Champ. I have a 5F1 Fender Champ clone that I purchased from the builder a few years back. It's always performed well, but I use it rarely. A few months back I powered it up and began playing through it and periodically there was a loud pop through the speaker. I rolled in new tubes and the same thing happened. I brought it out again last night and the popping was still present. Every few seconds while I was playing this loud pop happened. I can bias a tube amp and I can replace tubes, but my experience ends there. Can someone suggest what the problem might be and give me some ideas to check out? Your help is appreciated.

 

[dc007]

Tech time

 

[Dogbreath]

Tech time

Where I live that’s easier said than done.

 

[Dogbreath]

I thought about buying a Mojotone parts set and just rebuilding everything. It would be faster than leaving it with a questionable shop and cheaper than driving it to Los Angeles.

 

[dc007]

If you are positive it is not a tube then most likely it is a capacitor. Of course that is just a guess based on my previous amp that was doing the same kinda thing. I do not work on them.

 

[Dogbreath]

I just need to learn how to chase problems down. I guess I could just start soldering new ones in and quit when the popping stops. There really aren’t that many.

 

[DarrellV]

You are getting normal sound with popping? I'm thinking it could be a cap too. Charging and leaking.....

Just be dang careful around those things.... 450 volt rated could smart!

 

[Dogbreath]

You are getting normal sound with popping? I'm thinking it could be a cap too. Charging and leaking.....

Just be dang careful around those things.... 450 volt rated could smart!

Normal sound. No problem here about safety. I fully appreciate the danger and discharge and check with multi- meter before I poke around.

 

[DarrellV]

Normal sound. No problem here about safety. I fully appreciate the danger and discharge and check with multi- meter before I poke around.

I'm leaning more toward the caps attached to the tubes. The little ones in the signal path. Try them first.

 

[DarrellV]

http://triodeelectronics.com/5f1capkit.html

 

[DarrellV]

Or our guy right here at Amplified Parts

https://www.amplifiedparts.com/products/cap-set-fender-champ-5f1-tweed

 

[CB91710]

You are getting normal sound with popping? I'm thinking it could be a cap too. Charging and leaking.....

Just be dang careful around those things.... 450 volt rated could smart!

Where's the stand-by switch?

 

[CB91710]

I'm leaning more toward the caps attached to the tubes. The little ones in the signal path. Try them first.

Maybe a coupling cap getting ready to go, intermittently popping a DC pulse to the next grid.....

 

[DarrellV]

Maybe a coupling cap getting ready to go, intermittently popping a DC pulse to the next grid.....

Mazactly!

What he said!

Thanks CB. I had forgotten what they were called.

 

[JMP]

Where I live that’s easier said than done.

Where do you live? Others may be able to offer local recommendations. Also, it’s a Champ….it’s small and pretty cost effective to ship the chassis to a tech if needed.

 

[Cjsinla]

Popping can also be a cold solder joint. Open the amp up, turn it on, probe everything with a wooden chopstick. Poke every wire, cap, resistor and solder joint.

 

[CB91710]

Mazactly!

What he said!

Thanks CB. I had forgotten what they were called.

Umm... Just how many beers did you have last night?
It was right on the print that you posted

 

[CB91710]

http://triodeelectronics.com/5f1capkit.html

View attachment 549932

Or our guy right here at Amplified Parts

https://www.amplifiedparts.com/products/cap-set-fender-champ-5f1-tweed

Those are the electrolytic sets, which do tend to go bad with age and particularly with disuse, but the coupling caps aren't included in those sets.

Couple of .02 polyester Orange Drops will set you back a couple of bucks.
The Amplified Parts set includes the C6 bypass cap on the 6V6, but not the optional bypass on the 12AX7.
OTOH, the Triode set, while not including either bypass cap, does include the two filter section resistors, which likely won't need replacement on a modern amp/kit build.

 

[Dogbreath]

Prior to ordering new caps and resistors I decided to roll in another lightly used Electro Harmonix 6V6 and an EX 12AX7. The popping is gone and the Champ sounds great!!! I know that the issue may come back, but thanks to all of you I'll be prepared.

 

[The Ballzz]

Prior to ordering new caps and resistors I decided to roll in another lightly used Electro Harmonix 6V6 and an EX 12AX7. The popping is gone and the Champ sounds great!!! I know that the issue may come back, but thanks to all of you I'll be prepared.

May well have been a dirty tube socket that simply did not get "exercised" enough with your first round of tube swapping? I suggest also "exercising" in/out your 5Y3 rectumfryer a few times!
Just My $.02,
Gene