Dodgy amp needs repair

[sbattersby 115]

Hey guys
I have a fender frontman 15watt amp thats giving way too much fuzz. I am not using any effects or pedals just playing the guitar straight through the amp. The fuzz and crackling drowns out most of the actual playing and I was wondering if anyone knew why or if I could fix it myself.

 

[Enzo]

These amps are not complex, isolate the problem. COnnect the amp to a different speaker to see if hte speaker was blown. Headphones sound OK? Look for DC offset on the output pins of the op amps, a sign of failure. Got a scope to look at the waveform through the amp? COUld be a bad output amplifier chip.

And of course American amps must be upside down for proper operation in Austalia.

 

[mastertech]

Hi guys did you know that the fault could originate at the guiter electrical
part only and the amp could be fault free
sounds like bad input connections

 

[Enzo]

Well, that is certainly true.

 

[thedoctor]

Fender fuzz

Enzo got the first test perfect. Try the headphone jack. If it sounds good with headphones, you know a lot more about the problem's probable cause.

 

[sbattersby 115]

hey its me again. when i use headphones it sounds exactly the same. and when i plug in a mic it gives the same fuzz. When nothing is plugged in it doesn't sound just as bad but you hear it a bit. I have never repaired an amp or really anything much before so like keep it simple english please😉

 

[Centauri]

Most likely cause with these is output chip - it is the square plastic thing with 5 legs bolted to an aluminium bracket - type number TDA2050. These devices run hot, especially when playing at high volume, and the aluminium bracket / heatsink is not really big enough to keep the chip cool.

Cheers
Graeme

 

[sbattersby 115]

Thanks for the advice guys. could it be something simple like the input jack? something tells me its the problem, if so would it be hard to repair?

 

[Centauri]

In your original post you said "fuzz" - do you mean buzz? Hum/buzz/crackling, especially when the input jack is moved, could mean cracked solder joints on the circuit board - very common in later Fenders.

Cheers
Graeme

 

[sbattersby 115]

I could well be meaning buzz because I dont much know the difference🙂 Anyways it makes noise when it isn't supposed to like when a guitar is plugged in but you haven't played on it yet. Its strange because sometimes when you play on it the volume seems to increase itself and the pitch goes into an earpiercing scream. not nice

 

[sbattersby 115]

Yes also the input jack seems loose - when you plug the guitar in some times it almost falls out but I'm not sure how to fix it. I'll have to see if I can get an input jack from somewhere, but where from? A supplier? perhaps....😕

 

[Centauri]

First check the solder joints of the input jack on the circuit board - it is common for these to crack, and the jack will wobble around.

If you need to replace the jack itself (the original Fender ones aren't that good), you will need one of these :

,
but a bit of searching does not reveal a supplier in the uk. Cliff Electronics supplies them here in Australia as an Asian import, but Cliff in the uk doesn't seem to. Maybe another uk resident knows of a supplier?

Cheers
Graeme

 

[sbattersby 115]

THanks for the info guys, you rock!😎 I'll take a peek in the circuitry tonight and survey the damage

 

[sbattersby 115]

Hey guys! I resoldered the input jack as indeed it had cracked solder as you rightly suggested. It now sounds much better, thanks!