Repairing a snapped pcb

[Crystaleyes]

Hi all.

Recently picked a very cheap (20 Euros) Allen and Heath XONE 62 DJ mixer, which had clearly been dropped and upon opening up, has two snapped pcb's.

Other than bridging each trace, does anyone have any other suggestions or ideas as to how to resolve these?

There are probably twenty broken traces on each board.

The photos are of the board I glued with No More Nails (just to get things started).

I was thinking of using enameled speaker wire...

[petehall347]

Re: Repairing a snapped pcb

might be easier to use conductive paint on the thin close together ones .careful scraping and masking off first .

[Crystaleyes]

Re: Repairing a snapped pcb

Sounds interesting.

Didn't know that it existed

Just looked it up, wicked stuff. What a great idea!

[stj]

Re: Repairing a snapped pcb

the tracks arent the problem, reinforcing the board is.
it would be tempting to price up a new pcb from pcb-way,
it's only single sided.

[truclacicr]

Re: Repairing a snapped pcb

I would run wires from point to point. Tedious, but reliable.

[Crystaleyes]

Re: Repairing a snapped pcb

the tracks arent the problem, reinforcing the board is.
it would be tempting to price up a new pcb from pcb-way,
it's only single sided.

Thanks for the suggestions...

To be honest, board strength has been my main concern, although after soldering the thicker traces, the board pictured is already fairly rigid again.

I should finally be back in England next month, earning real wages, so I was thinking of ringing up Allen & Heath and seeing if they had any old 'blank' boards laying around that they would sell?
I need both the boards with the LED power bars.

And seeing how I essentially got the mixer for free, it had also crossed my mind to get some replacements made, although that is something I've never done before.

I'll see if anyone here sells the conductive paint first.

[Crystaleyes]

Re: Repairing a snapped pcb

I would run wires from point to point. Tedious, but reliable.

Do you reckon I could get away with enameled speaker wire on the thinner traces?

[tester272001]

Re: Repairing a snapped pcb

To add strength. Perhaps use some epoxy like JB weld to glue the component side with some plastic to help prevent flexing.

[Crystaleyes]

Re: Repairing a snapped pcb

To add strength. Perhaps use some epoxy like JB weld to glue the component side with some plastic to help prevent flexing.

This is also what had crossed my mind.

There are areas with just resistors or links (which could easily be replaced with longer legs), where another piece of board could be added and the holes re-drilled with a Dremel.

[petehall347]

Re: Repairing a snapped pcb

with it being audio the routing might be important .. i know wires in the wrong rout can cause havoc

[truclacicr]

Re: Repairing a snapped pcb

Do you reckon I could get away with enameled speaker wire on the thinner traces?

Any insulated wire should do the job. Audio is low frequency, so you don't need to be concerned with exotic stuff like transmission line impedances, unless you're an audiophool.

[momaka]

Re: Repairing a snapped pcb

Do you reckon I could get away with enameled speaker wire on the thinner traces?

You could.

But I personally would use (and have used in the past) very thin bare copper wire. The best place to get this is to find some 24-18 AWG stranded copper wire with fine strands and then pull individual strands from the wire to put on those traces. The neat thing about using very thin bare wire is that it is easier to solder and you don't have to worry about removing any insulating coating. With enameled wire, you have to strip the coating, and it has to be done well so that each wire solders properly to each trace. But the stripping will make the job much harder and slower, IME.

As for PCB reinforcement, you can do that on the top with some scrap plastic or wood or PCB pieces and hot glue. I know it sounds janky/ghetto as heck, but it works really well, especially if you happen to have good quality hot glue and get it extra hot on there. I have fixed a number of PCBs like this before, and they are still holding up well - even to slight abuse.

[stj]

Re: Repairing a snapped pcb

the way to fix broken traces is to scrape any solder mask off whats still there and solder copper wire onto the trace.
i like to strip old power cables for nice copper strands
the bigger pads i use offcuts of solid copper from house wiring.
transformer wire is tempting but getting the enamel off them is a pain.

[Crystaleyes]

Re: Repairing a snapped pcb

Some excellent suggestions, so thank you sincerely.

One observation is that some of the broken traces are really fine, therefore it is easier to run longer lines and those would need some form of insulation.

As for using solid copper.. I like that, and have lot's of that here.

I-ll keep you all updated as I do this work

[momaka]

Re: Repairing a snapped pcb

Maybe it's the size/zoom of the images, but the small traces don't look that bad to me. Would/should be pretty easy to do with just shorter pieces of very thin bare copper wire (again, strands taken from bigger wire, like 24-18 AWG.) I've fixed PCI-E lanes on a graphics card with this method and it's certainly easier than running long pieces of insulated wire.
The only trick to soldering all of the fine wires next to each other is to 1) always keep a good amount of flux on everything and 2) very little solder on the soldering iron's tip (close to none would be ideal so you don't run the risk of bridging the wires.) And on that note, use solder that is eutectic in nature (63/37 OK). As much as I like 60/40 for general repairs and its ruggedness / flexibility, I tend to avoid it for SMD and very thin traces, because it has a higher chances of bridging over if I'm not extra careful. In contrast, the cheap 95 Sn / 5 Sb lead-free solder I use is quite eutectic and I've really gotten used to it for SMD and fine trace repair - the moment I pull the soldering iron away, it hardens.

[harp]

Re: Repairing a snapped pcb

It is one side pcb with not to much fine traces.

I preffer to use a used (soaked with tin) pieces of soldering wick (yes I collect it), it is ideal to combine and reinforce big area, like grund plane or power rails. It is not so stiff like solid copper wire, and it almost flatten with surface on pcb when done. It cover large surface with equal strenght. Try.

For fine traces, I preffer to use a ripped fine traces from scrap board, it is much less hassle then to use round wire. But you must prepare them... I think that in your situation is not necessary to use fine ripped traces, use a pretinned fine copper wire.

https://m.youtube.com/watch?v=igUjV-u4BmQ


To repair fine traces who has a near one by side, like on your edges, use a technique to separate workarea like in this video

https://m.youtube.com/watch?v=PO6b5VD7bbg

[truclacicr]

Re: Repairing a snapped pcb

People seem to be focused on bridging the crack. Instead, if a trace connects a capacitor to a resistor, say, then run a wire between the solder terminals of the two components.

[Crystaleyes]

Re: Repairing a snapped pcb

Some excellent tips and suggestions, most of which I can see being extremely useful, so nice one, for all the input.



Haven't had a free moment to try any of these out yet but gonna get on it in the coming days.

Wish me luck!

[harp]

Re: Repairing a snapped pcb

Example: used desoldering wick (bottom left part) and twisted pretined wire (centar)
When you finish share outcome pics... luck