Noob wants to work on Crate GX-30M input jack

[hotmustard]

Id like to try to re-solder the input jack on a Crate GX-30M, and I'm worried about getting shocked by capacitors. Assuming I unplug, keep one hand in my pocket, and take off my ring, could this thing kill me? I will not take anyone's opinion as any guarantee for safety. Sorry for the noob question.

[soundguruman]

When the unit is unplugged from power for several hours, the charge drains, and you are safe.

[52 Bill]

Welcome to the place. Congratulations on taking the time to ask the question regarding your personal safety, rather than assuming that it wasn't going to be a problem.

In most amps, once the ac cord has been pulled and the amp has been sitting for a while, the internal stored voltages will have dissipated to a safe level. This Crate being a solid state amp will not have the high voltage levels that a tube amp would have, so that will make it even safer for you to work on. If you want to be certain, use a volt meter and check the voltage on the large filter caps once you have the chassis removed.

Resoldering an input jack should be an easy project for a beginner. Here are a few tips. Before removing the chassis from the cabinet, take notes or take pics showing how the speaker wires are connected, any cables to a reverb tank, etc. This will make reassembly easier when you are done.

Once the chassis has been removed from the cabinet you will need to remove the pc board from the metal chassis. If you're incredibly lucky, the jack will be mounted to a small pc board, more likely the entire board will need to be removed. Again pics or notes will help later in reassembly. Try and remove as few wires from the board as possible, as you don't need to entirely remove the board to resolder the input jack.

A lot of Crates use push on knobs and pots that are not mounted to the front panel. Be careful when removing and replacing the knobs so as not to damage the pots themselves or their solder joints. In fact once the board is out you should visibly inspect all of the solder joints to the pots and any other jacks. When I replace the knobs, I squeeze them on, pushing on the knob with my thumb, while pressing in on the back of the pot with my index finger.

Resoldering should be simple if you have the correct tools. You will need a small iron, some sort of desoldering device (wick, pump, etc.), and some rosin core solder. You should remove the old solder and then resolder the joint for best results. You should also inspect the pc board traces where the jack in connected, as sometimes the copper trace breaks and goes open circuit rather than the joint itself going bad.

While the chassis is out of the cabinet, you might want to check to see if the pots and jacks need to be cleaned and serviced as well.

Best of luck, and we'll be here to help if you have any other questions.

[hotmustard]

Thanks a ton, bros. So I opened it up and totally did not die. I think I was even able to fix the solder joint, too, I think. I took pictures as recommended, which really was clutch to getting the pcb re-connected. At first, it didn't really look like there was anything wrong with the solder joints, but I'm not used to looking at PCBs, but then I think I saw that there was like a little ring around the center of one the solder dollops which I interpreted to be a little crack. So I dropped a drip or two from my little walmart iron on there and pieced it all back together but when I turned it on, oh noes I got zero sound. After tearing it apart again, there was the little cord that connected to the speaker wire - flapping in the wind and not connected to its pcb jack. Duh. Anyway, it is all back together and I haven't heard any crackling like before but now I have a little rattle in there when the volume goes up. I'm pretty sure it's due to a screw on the pcb that I was too afraid to put too much pressure on when re-assembling. I'll get it straight. Anyway, thanks for all the advice! If I get it working completely, I will have saved a lot of bucks by buying used and repairing. Plus it was fun.

[52 Bill]

Congrats on the repair. Don't it feel great to fix stuff?

...now I have a little rattle in there when the volume goes up. I'm pretty sure it's due to a screw on the pcb that I was too afraid to put too much pressure on when re-assembling.

Is it a physical/mechanical rattle or something from the speaker? It may be hard to tell.