2 amps, 2 issues :/

[pontiacdude210]

I appreciate any input on this, I have a little electronics experience but not enough to tackle these without a little direction.


Just bought a Fender Ultimate Chorus 2X10 Amplifier. 2 Inputs, Reverb effect built in, etc. Solid state digital amp. Got it home and there was a lot of buzz on the clean and drive channels. About half volume it starts popping loudly. There is a repetetive cracking noise any time I play, but not just sitting. The buzz is there even when nothing plugged into inputs. I took the cover off, removed all the connections and cleaned them and reconnected them, put a nut on the input jack that didn't have one. Found 2 capacitors that had been glued together. The glue was coming loose so I ran a strip of electrical tape between them to hold them from shaking and breaking solders. Put it back together and it sounded great. After playing at 3/4 volume with the gain way up on the drive channel for about 10 minutes, no touching the amp, the crackle came back and it started popping again. I can't figure out where to start testing components.



Also, I have a Prestige 60W PA amp. It runs fine then all the sudden, loses a lot of power and sound quality. I am thinking it is overheating but the heatsinks feel cool. Any input here appreciated.

 

[Grossel]

Hi.

You said it was GLUED together. To capacitors? Did you bought this amplifier used? It make me think that someone has tried to "fix" it before, and that the "fix" somehow went wrong. Did you solder them properly?
How about some close up pictures of the amplifier's inside?

For the other one, it could be everything from the power transistors being loose from heatsink to bad soldering.

 

[dustysnakes]

Fender actually does "glue" the power section caps together from the factory on a lot of the models. I think it's an anti-vibration thing but I have not seen that it works terribly well. My first check, given your trouble shooting would be to look at the actual solder joints on those caps. Of course, there are a few other problems it could be. As I remember, those amps also have a ribbon cable connecting the pre and power amp section which is prone to bad connection and will do some real squigly stuff at higher volumes because of the vibration involved in a guitar amp. Like Grossel said an actual picture of the board would help a lot here.