Major PCB repairs

[cm961]

Hey guys,

I need to perform major circuit board track repairs on this amp I got. The tracks that need repairing are the main output ones, so we'll be looking at high current (60V mains, 250W max output). I have this little conductive pen thing but I don't really understand how it works. Does anyone know of a good product to do such a repair?

Thanks everyone,
Pete

[Apogee]

A trick that I've used in the past in such cases is to simply overlay the burned track with solid core wire. Just bend it to follow the old track's path and solder at the next undamaged junction point...

Works well because you don't have to worry about the wire not being able to handle the current (just choose a large enough size)... In other words, don't use 28 gauge...

If it is a long run, simply scrape away the solder mask in a couple of places on the old track and tack the wire down with solder to hold it in place... I've actually never had to do this because the burned areas usually aren't that big...but it would work fine if you need a way to secure the wire down...

I've repaired some badly burned boards this way and they've worked like a charm...

I don't think that I would use the pen in this case... There are self stick copper traces available (don't know where but I have seen them) for such repairs... I've always just used the wire trick because it's cheap, fast and I always seem to have just the right stuff laying around...

Good luck,

[SkinnyBoy]

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Thats what the guys in the business do....
But thats normally with BROKEN PCBs where something has been droped, and the board broken the whole way through..

[cm961]

thanks guys,

I think I'll try a combination of the solid wire and the pen. You see, I need the holes to be intack because of the way the power transistor pokes through the heatsink. The track is against the heatsink (well not touching!) and the transistor comes from the other side of the heatsink. So the solder spot is on the other side of the board from the track. So its going to be hard to solder it. Maybe I could make the hole bigger and poke the solid wire through it. Thanks for your suggestions!

Pete

[Apogee]

Pete,

Would it be possible to run the wire on the underside of the board and go from the power transistor to the next junction point of the original trace but on the opposite side of the board?

Just use insulated wire... The side of the board that you route the wire on is not critical as long as the circuit is still going to the correct place...

Might be easier...

A picture would be great if you could post one...

Just my thoughts...

[cm961]

That's a great idea, thanks a lot!

I'll try to get some pictures up, but I don't have a camera. The amp is a carvin DCA-800. Quite a nice amp, looks like solid construction. It will be really nice if I can get the channels to work!

Pete

[jackinnj]

3M part number 1181 (allied p/n 617-5061) at www.alliedelec.com The tape is very easy to use -- I use it to make top-side ground planes -- It's adhesive on one side and you can cut it to the same trace width with a pair of scissors. Solders very easily. Here's a link: http://products3.3m.com/catalog/us/e...tronicsesm_3_0

If you break a 10 mil trace, use wire-wrap wire. Place a small bead of solder on one side of the damaged track. Tack down one end of the wire to the bead (I hold in place with a tiny screwdriver). Solder the other end, then go back and solder the tacked end. This is somewhat like the procedure I use for SMT devices.