Popping from Fender Frontman 212R

[mylogon]

Hi guys,
i bought a 212R about 4 years ago and since new it crackled and popped while the jack lead is plugged in. While the lead in not plugged in it is silent, which, i believe, means the silent switch is working?

after the amp is switched on, with the jack lead plugged in, then it does it's crackling and popping for about 5 minutes, then it tails off completely and stops.. this is the only reason i haven't stuck my foot through the speakers.

could this be down to the circuitry warming up, or is this actually fixable? I am quite capable of soldering etc, i just dont really understand how it all works.

if anyone point me in the right direction, or tell me where to throw the amp, then i'd be very grateful.

thanks a lot,
luke

[Jazz P Bass]

Crackling & popping could be caused by just about every circuit in the amp.
The tech approach is to narrow down "where" it is occuring.
So you will need a couple of volt meters, good soldering equipment & possibly a scope.
Or you could take it to a reputable tech

[mylogon]

is there anything in particular i should be looking for, or tests i should be conducting?

and as for the reputable tech, i have taken it to a friend who is a keep musician, come electrician. he couldn't find anything. not sure if he actually tried too hard to find tbh. and to a proper electrician, well... i think i'd have to get a remortgage to afford that...

thanks,
luke

[jmaf]

Humidity in resistors cause crackling, then when they warm up they dry. Happens especially with carbon comps, not the case of the 212.

Bad solder joints could also cause this(more likely scenario).

If you'll open the amplifier(disclaimer: I'm not saying you should) you could poke around with a chopstick, pushing solders and component legs into the PCB and tapping them. If one of them causes the crackles to increase, you've found one of the culprits.