#1
I have a Fender Frontman 15G amplifier. One of the prongs on the input jack was broken in half so I used solder to connect it to the circuit board. I desoldered and resoldered the jack twice before I got it right. Anyway there's a grounding problem with my amp (which existed long before my jack problem). For example touching the input jack and the metal handle will cease the loud ass buzzing that otherwise never goes away. I tried soldering a wire from the metal of the speaker to the metal seperate from the electronics, and the buzzing went away, but instead I kept getting loud ass squealing that was intensely high pitched. I think it might be some kind of feedback from wiring to the speaker... Either way I took it off and I'm back to ungrounded buzz. Where and how should I solder the wire?
#4
When I touch the guitar it increases. When I touch the jack and the metal the circuit board is mounted on it disappears. When I touch the speaker and metal the circuit board is mounted on it disappears. I originally thought that my input jack had one prong disconnected from the board. But there's 4 prongs. There's two side by side, one above them in the middle and one below them offset. I think the bottom offset one is grounding? I'll resolder it and see how that goes.
#5
I had the same issue on my 15G, though I never tried to fix it... I just kinda lived with it until I could afford a new amp

If you touch the place on the metal of the speaker that you soldered the wire to, does the buzzing go away? If so, run a wire from there directly to the ground prong on the power input jack.

If it makes that high pitched squeal when you touch it, then try running a wire from any place you can touch that makes the buzzing go away directly to the ground prong.

FYI, you can just tape the wire on to test different locations, so you don't have to keep soldering and unsoldering... just make sure to solder it when you find a good spot.

EDIT: I just read your last post... so yeah, try soldering the metal part of the speaker directly to the ground prong... The reason I say that is because the chassis (I'm assuming you soldered it to the chassis) might not be properly grounded itself, it's hard to know with a low end amp like that
Last edited by HibyPrime at Feb 20, 2009,
#6
Actually the main ground is grounded to the same plate of metal . And before I solder I hold the wires down with my hands, and it'll go away. But after soldering I got some high pitched whine. I just resoldered it. It started whining again when I got my hand near...
#7
I was almost done putting it back together... When I noticed that one of the prongs on the back board where you plug the power in was crooked. I intended to straighten it real quick with a pair of pliars before squeezing it in and screwing it. Except it was still plugged in. So the circuit broke in my room and I had to go flip the switch on the circuit breaker. Now my amp's LED won't come on and it makes a loud noise when it comes on. Did I blow the fuse in my amp, or another component?
#9
Nevermind. The LED works fine. It only makes that noise when the jack's at a certain angle. It's still not working though, and now there's an LED on the circuit board lighting up accompanying said noise. I'm sure it's for diagnostic purposes, but I don't know what it means. I really wish I didn't **** up that last time. EDIT: It was working fine before I put the amp together. But once I did that's when it went to hell, same as last time. Maybe the plate of metal I grounded onto isn't doable once it comes into contact with other things. But that doesn't make much sense, as the other ground is on there as well. Could it be one terminal touching the grounding prong?
Last edited by dz_alias at Feb 21, 2009,
#10
The LED is a clipping diode. It's lighting up because there's a ****load of signal going through it.

Just go through and recheck eveything. Make sure nothing is shorting, your solder joints aren't cold or ****ty-looking, etc.
#11
It wasn't my jack, it was the metal brace that holds the circuit board steady. Every time it came into contact with the metal plate it would spark and make noise. So I removed it, and I don't remember my Frontman 15G ever sounding so notungrounded. It's pretty decent. Question! Was removing the plate bad? The component on the end that the plate screws onto looked important and when I touch it it burns. Probably because it's active. I dunno if the plate served as some kind of heat sink? I don't think so, but...
#12
Yes, it's a heat sink.

NOW I remember what it was. You are SHORTING the voltage regulator to the chassis ground. Find something non-conductive to put between it and the chassis.
#13
is that what the component is? A voltage regulator? Because there was something nonconductive between it and the chassis... This little rubber square things.
#14
Yeah, a voltage regulator or an output chip that drives the speaker (never really figured out the latter).

Point is, something about that thing just isn't right. It HAS to be heat-sunk or it'll burn up. Replace that rubber thing with another one. Be sure to get some silicon grease in there too. It help transfer the heat.
#15
Mmk. Thank you. I'm done with it for tonight, but I'll tinker with it tomorrow.
#16
Quote by Invader Jim
Yeah, a voltage regulator or an output chip that drives the speaker (never really figured out the latter).

Point is, something about that thing just isn't right. It HAS to be heat-sunk or it'll burn up. Replace that rubber thing with another one. Be sure to get some silicon grease in there too. It help transfer the heat.

My little brother's been using it because he's impatient, so I haven't paid it any mind. I just told him that if it catches on fire to unplug it and put it in the washing machine on "Heavy Duty."

Are you sure it'll burn up though?

I think the problem with it is that after taking it apart the first time, I lost a couple pieces that were used to hold the "heat sink" to the circuit board. I don't think it's supposed to be conductive, so there was a layer of rubber inbetween them and plastic pieces between the screw. If the screw's conductive, I don't see how this would work, but I'm assuming that's why it starts sparking and sizzling whenever I have it touching :3.
#17
Your little brother should be slapped with a trout.

Those plastic things and rubber things are insulators. THe plastic insulated the screws and the rubber insulated the regulator. You HAVE to have that **** on there or it'll fry the amp.
#18
What if I lost the little plastic insulators and they got sucked up by the evil vacuum cleaner :3?
#20
Googling "little tiny plastic things" didn't help much.

I would find something else to use in place of them, but I'm worried whatever I may use might not be heat-safe... I mean it'd suck to put the heat sink back in, only to have it catch on fire.