Need Car Amp PCB help

Hey guys, need some help. Bought a sundown 2000 car amplifier. RCA plugs on input, output and master/slave all broke off. I attempted to resolder using absolutely no knowledge at all. I can’t really take the board out to access other side. I believe I damaged the pads on all connections, I mainly need the input, so how do I attempt this? Outside contact is ground correct? And inside is actual connection? Can I use copper tape after scraping board to reestablish pads and connect the prods/connectors/thingies using solder on opposite side? Thank you for any help

HI Dalilydontspilly, welcome to the community!

When repairing PCBs with lifted pads, many manufacturers/hobbiests find the best material for the application is something called Wire Wrap. It’s a single conductor wire that has an insulation material, commonly refered to as Kynar, or Polyvinylidene Fluoride (PVDF) that does not melt/creep up the wire when soldering, making handling in tight spaces much easier.

Here is some 30AWG Wire Wrap from Adafruit 1528-2005-ND

If you lifted a pad you can scrape the solder mask covering over the trace back to where it’s still connected to the PCB and solder there. Make sure to use flux or solder with flux core so you do not continue to lift traces. Hanging out too long and too hot will unglue the copper from the PCB and you’ll continue to lift traces/pads.

Hi Dalilydontspilly,

That is quite the tongue twister :slight_smile:. Nice amp, and photos. I have seen this before, and you probably are correct the pads are probably ruined. Since the pads are on the bottom of the PCB, unfortunately you would have to pull the entire board out. This is a little bit of work, but not too bad. This means unclipping/unscrewing all the mosfets from the frame (probably getting messy with heat sink paste), taking some hardware off, and sliding the board out from the side. You then should be able to access the pcb traces on the underside, and you will most likely have to solder new connections to them using wire mentioned above or of your choosing. Remember to re-install the heat sink insulators on each mosfet if they are supplied that way. You should be able to line up the connections visually and determine how they are wired. If you can’t get access to the solder trace, you may have to take a thumb tac or something and scrape the paint away from the trace to solder to. Remember we have soldering tools, and soldering blogs on the forum if you need. One is below as an example:

In case you need extra thermal paste:
Thermal paste 345-1006-ND

Very good reply, I appreciate it, I’ll use this as my guide. So am I correct on the inside 2 being the actual connections? Then the outside 2 are ground? I believe I fried one side of my rcas because I thought the sides were support so I just sautéred everything together. Lol whoops. Thank you a bunch

Didn’t see this response at first, but ok, awesome. Never heard of it but I’ll have to check it out, this would be better than copper tape then? That’s something someone else suggested. And alright, yeah trying to get the existing solder out of there from the bottom even I was burning the board. Someone was trying to fix it before me as well. I only made things worse lol

Hello again Dalilydontspilly,

If you soldered these all together, and hooked the amp back up, it probably wouldn’t hurt anything as you’d only be shorting out a mili-volt signal. These are shielded type RCA jacks, the two outside connections on each column is technically a shield ground, but also serve for mounting the jacks and solidarity. You will then see 3 solder areas inside these, these are where the actual audio signals will be transferred.

The single connection towards the outside of the board is signal ground, and the remaining pair are the positive signal inputs, one for left channel and one for right channel. The RCA jacks look to be shot as they are missing the internal connections, I’d recommend 1175-1498-ND click here. You will have to cut the male ends off, strip, and wire the jack wire ends through the panel to be soldered to the board. We have some jacks located in this link, but not sure they would be a direct replacement.