#1
So I have a Marshall MG15CDR... 'InB4' "that's my first problem". I like this amp. But anyway.

It's my bedroom practice amp, or at least, it was. It randomly broke on me one day, and I'm not paying to get it fixed, it's just not worth it. But I assessed it and it seemed the input jack was broken, so I tried to replace it. The headphone jack wasn't working either, so tried to replace that as well. When I went to unsolder the headphone jack, the print on the circuit board just started peeling off. It's torn away from the board itself, and looks no good at all. Also, on the input jack side, there's a lot of wear around the holes for the jack legs.

Here's some pictures:
http://profile.ultimate-guitar.com/TheKraken/pictures/personal/982267/
http://profile.ultimate-guitar.com/TheKraken/pictures/personal/982266/
http://profile.ultimate-guitar.com/TheKraken/pictures/personal/982265/
http://profile.ultimate-guitar.com/TheKraken/pictures/personal/982264/
http://profile.ultimate-guitar.com/TheKraken/pictures/personal/982261/

I soldered in the input, but the amp no longer works, it powers on, but, nothing.

I was wondering if anybody could give me any clues on what to do?

I know the most common opinion will be "get a new amp"... Money's tight and I'm saving up for either a new cab or a new practice amp, but I would like to have this working. Just for show really
#2
The day that works I'm Jesus... You should probably solder off everything, make a new PCB and solder the components onto the new one that you've made yourself.
#3
You've lifted some of the pads for the input jack...some are repairable for sure, but some may not be...can you take pix of the top of the board at both the input jack and the headphone jack. If you do that I can prob help you out on where to solder and cut traces to repair.
#4
if there are traces on the top of the board like I'm thinking you can be up and running with a little precise work. otherwise you're going to need a new pcb or the schematic to figure out where to jumper wires too
#5
In all honestly, what you really need is a new amp.

I have a 5W first act amp sitting in my closet that I would give to you. Perfect for a small practice amp til you have cash to get a new one.
"I have good eye-sight, insight, and foresight. How could an
intelligent hare make such a silly mistake?"
Last edited by HowToFly at Apr 13, 2011,
#6
By the top, do you mean the side with the solder on? I have pictures of that. Do you need clearer ones?
The other side of the PCB is blank.
#7
The point isn't about having an amp up and running, it's about fixing this one. I know I need a new one, because even with this working, it's not amazing.
#9
I mean right now there are only pictures of the "bottom" of the board...the top of the board is where all the parts are. The parts you are concerned about are through hole parts so they are affected by both sides of the board. by blank you mean no writing or what? no traces? From the current pictures some are helpful but I would like pictures of all 6 input jack pins..Right now I can only see the side with the trace floating clearly.

Basically if you could get clear pictures of the input jack's six holes from both sides I can tell you if a repair is possible without a new pcb. (it should be but I need to see where the traces for each pin go and how bad each hole is from both sides)
#10
Well, the input jack is the main problem, which only has 4 pins. I'll take clear pictures of each side at each jack.

Can the board run without the headphone jack in?
#12
In either case you might be able to sand away at the board to reveal the trace and solder directly to that, otherwise easiest option is just to follow the trace, and solder a piece of wire to the lead on the jack and the closest point along the trace.

Not sure which picture is identifying which jack, but for this one http://profile.ultimate-guitar.com/TheKraken/pictures/personal/982266/ you can just make a solder bridge with the pad beside it, since they both connect together.

You might be able to do the same thing here: http://profile.ultimate-guitar.com/TheKraken/pictures/personal/982267/ but they aren't quite as close together, so a short piece of wire would be your best bet.
Last edited by take_it_t at Apr 13, 2011,
#13
Thanks for the help guys! I'm pretty sure I know what to do now, but my soldering iron has just given up on me. I'll have to get a new one and then fix this.

But thanks!
#14
From those pics it should be easy to fix both jacks. Only one input jack appears to be bad which has the copper trace exposed so just scrape away to reveal some more copper and solder to that. Be careful not to scrape away the GND plate too and then solder everything together by accident.

the headphone jack just needs the two in the large trace on the right to be connected to each other so you can scrape away some trace for the back one or just wire that pin to the middle one. Should be able to do nothing to it for it to work as well. I'd just leave it that be as is. The one that's floating, I'd just be careful with it breaking, but even then you could just jump a wire from the jack's pin to the pin the trace goes to. You might even be able to leave it without soldering as it's GND and you already have the otherside of that jack connected, but since it's a single sided PCB, another pin might require it to connect to the GND plane.