Cut traces for diagnosis?

OMGCat!

OMGCat!

Super Member
Has anyone ever seen someone cut traces on a board to diagnose an issue?
I just got finished up working on a SU-V8 that had prior repairs and I noticed that someone had scratched away some of the traces and then just gobbed solder over the break when they were done. Not pretty and very destructive IMO.
Has this ever been a recommended repair practice?

I ended up cleaning up the scraped off solder mask and using small bits of solder braid to join the break. It was either that or drill small holes and make jumpers from leads but this seams to have worked well and looks acceptable.
 

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I've seen it many times. Including cutting one channel output (trace going to the speakers terminals) and bridging one channel to both speakers.

I'd do it if it were less invasive or less destructive than desoldering hard to reach components. Never did it yet. I did fixed those cut traces.
 
have only have seen it done when the circuit is changed to accommodate a design change because of obsolete components . i recently came across an amp with component leads cut because its much easier if you have to undo lots of screws to get to the solder side .
no idea why those traces were cut as can be diagnosed quicker with a multi-meter on ohms .
 
I've only seen it on production changes as well but I'm pretty sure this was done afterward by someone.
There's no issue accessing the traces at all. The bottom panel comes off and everything is right there.
 
not a typical repair practice. And repair should have included a piece of copper wire to bridge over the break rather than just solder.
 
I've heard of it, never done it myself. As others have said it just seems too destructive.

I've never heard of any techs whom I respect advocating this.
 
Very seldom I have had to do this to track down a short when there are multiple branches in a circuit. The proper method is then to solder a wire across the cut when done.
 
I can see how it might be the only way to pin down a really difficult fault, but personally I would explore every other option first. I also think that solder blobs are not a reliable way of re-making the join in the track - as the doc says :thumbsup: - solder a wire across the gap. ;)
Ray Gianelli said:
I've never heard of any techs whom I respect advocating this.
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In that case I absolutely totally disagree with doing this terrible thing. :D
 
dr*audio said:
Very seldom I have had to do this to track down a short when there are multiple branches in a circuit. The proper method is then to solder a wire across the cut when done.
Click to expand...
Warren, I've had good luck using the Keithley 2015 in 4 wire ohm mode. I picked up a set of Kelvin leads on the auction site for $17 shipped. You can see fractional ohm variations as you get closer to the short.
 
there are many amplifiers around with "solder bridges", that you remove to insert an ammeter, or to change from 220 to 110V, or other things like that (I have here a reverb unit plenty of those connections, seems the PCB is shared by 3 or 4 models, and indicated which bridges must be connected in each model), so it seems a single blob of solder is strong enough if the gap is small. I wouldn't worry too much if the gap is small. I've noted those "gaps", when done at the factory in the PCB use to have a "V" shape, or a kind of "H" with both traces interlacing.
 
Ray Gianelli said:
Warren, I've had good luck using the Keithley 2015 in 4 wire ohm mode. I picked up a set of Kelvin leads on the auction site for $17 shipped. You can see fractional ohm variations as you get closer to the short.
Click to expand...
I've done this. Sometimes it's quicker to desolder a few components or cut the trace.
 
Seen it, fixed it, but I've never done it as a diagnostic tool. I have done this for modification purposes in the past though. +1 on bridging with a piece of wire though, even a cut off component lead laid across the slice will do the job. If its wide trace, bend the lead into a U so its got a bit more area to conduct through.

The fun ones are boards that have gotten cracked from some sort of mechanical damage. I've bodged together stuff with a dozen or more cracked traces. Its an absolute mess underneath once you get it all patched up but people look at you like a miracle worker when the whatever comes back to life.
 
I've fixed cracked boards too. It usually ends up being a mixture of jumper wires and soldered on leads.

Like I mentioned in the OP I used desolder braid to jump the break as the traces are for the main filters among other things and I wanted to have a nice wide conductor (the first pic is before, second is after). The braid sucked up the solder and stuck nice and firm to both sides of the cut so I think it's good to go. Now it just looks like it's got shiny rectangular bubbles on some of the traces rather than gouged up mask and globbed on solder.
 
solder blob will be fine to fix ..cutting it is not so good if not really needed . everyone has their own way of fixing things .its whatever works for you
 
OMGCat! said:
Has anyone ever seen someone cut traces on a board to diagnose an issue?
I just got finished up working on a SU-V8 that had prior repairs and I noticed that someone had scratched away some of the traces and then just gobbed solder over the break when they were done. Not pretty and very destructive IMO.
Has this ever been a recommended repair practice?

I ended up cleaning up the scraped off solder mask and using small bits of solder braid to join the break. It was either that or drill small holes and make jumpers from leads but this seams to have worked well and looks acceptable.
Click to expand...

Yes I've ran across it, and I would remove components instead of hacking up a board like that. Plus simply dragging a blob of solder across it is a half assed way to repair it.
With a trace that wide I like to lay a small straight edge on the board, to help make the scraped area look neater. Then I tin the area with solder, following up with de-solder braid to remove the excess.
I then clean off any flux residue from the area. Prepping the area like this, helps insure the entire underside of whatever jumper is used, actually makes a good bond to the board area. As for the jumper itself I like to use something flat rather than round.
 
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