Need Help Repairing Amplifier with Possible Corrosion

[Dom_]

I have a Pioneer 820W car amplifier, model number GM-5500T. It was given to me by a neighbor, and worked fine for about 6 months. I had a problem with my head unit, so the amp went without use for about 2 months, but was still connected to power. When I got a new head unit installed, I had no output to my speakers. I back to see if I could find the problem, and discovered that the amp was not powered on despite being connected properly, and neither fuse being burned out. I considered testing voltages on the circuit board to find the issue, but I have a cheap multimeter that hardly works, and I wouldn't trust myself poking around while something is connected to a car battery. I disconnected the amp and brought it inside to disassemble it, and found that all the components looked to be in good shape. No swollen capacitors, no signs of fire or shorts, and didn't smell bad. However, on the back of the board, there is a brown substance on some of the soldered connections. I know it looks burned in the pictures, but it's more of a translucent amber substance, and there are white splatters around it. I'm not sure if this is some type of corrosion or not. I thought maybe I could just re solder the problem areas to take care of it, or maybe there's some kind of solution to clean it, but I really have no idea. I've attached images to help. Any input would be appreciated.

 

[Heliman]

That brown stuff is just rosin from rosin core solder. Doesn't hurt anything

 

[davenn]

I know it looks burned in the pictures, but it's more of a translucent amber substance, and there are white splatters around it. I'm not sure if this is some type of corrosion or not. I thought maybe I could just re solder the problem areas to take care of it,

yup agreed with Heliman .... just a bit of solder flux

 

[shrtrnd]

It sounds like your amp took a hit, but I'd recheck all of your original rewiring, just to make sure something in your
new installation was not wired incorrectly. When you said 'neither fuse was burned-out', did you mean the fuse
in the amp and the fuse in the new unit? Did you check the fuse block in the car itself to be sure that fuse is alright?
Is your meter working well enough to make sure you have power TO the amp, before assuming the amp itself has
a problem?

 

[Dom_]

There are two fuses in the amp, which are both good. There's also an in-line fuse on the power wire running from the battery to the amp, which is also good. Also checked any fuses that might affect it in the car too, and none were bad. I can check the wires with my multimeter today. Would I just set it to test voltage and put positive to positive and negative to negative?

 

[shrtrnd]

Yes. The first most obvious thing to do, is to check that you HAVE power to the unit.
You'd check the 12VDC (set meter for DC voltage, greater than 12V), 'hot' wire, and chassis ground of the vehicle
if an actual ground wire is not wired into the unit.
The two fuses in the amp are probably power output fuses from the amp to protect your speakers.
I don't know who wired your set-up, but you may still have a power input fuse inside that amp that you haven't found yet.
If you find you have 12VDC going into your set-up, somebody here can probably try to add input of what to check next.

 

[tedstruk]

just a guess... when you hook it up, make sure you check the wire color from the amp and trace each wire color, its easy to get excited and hook the wrong wires up to the wrong place.

 

[Dom_]

Just tested, and the line to the battery is outputting 11.06 volts. I had a capacitor hooked up to it at one point so I wired that up and checked the output, and that's fine. So I guess it's the amp. It's ok if I can't get it working, but I'd much rather be able to fix it now than wait another 3 months before I've made enough to afford a new one.