Delicate soldering job.

[dobbslc]

I've been given this kart digital dash to replace the switches on.
My friend had a go but couldn't get anything to work, the "tracks" look too far gone to me but does anybody know how I could try to sort it?

Here's a bag of new switches he's given me.

 

[mtt.tr]

Clean it up with some flux and see of it will take some solder

 

[Gragson]

Tell your mate to undo hat he did

 

[dobbslc]

I can now see how it's switched, the tiny track you can see going up under the screen is the switch line for want of a better word and the main background of the board is the common, so I need to get a strand of wire attached to that tiny track so I can then remotely solder it to the switch tab then the main board side of it should be easier...
This is on the limits of my vision let alone skills !!!

 

[mtt.tr]

Enameled copper is pretty useful in this instance


Dare I say it. And hot melt glue

 

[Parm]

Enameled copper is pretty useful in this instance


Dare I say it. And hot melt glue

I’ve used this trick in the past

 

[julianf]

If the unit was in that condition before work started, are you sure it's just the switches?

Unless it's some sort of hf digital thing, remember you can pretty much do point to point wiring with thin insulated wire over broken tracks. Just look for the component that the broken trace comes from and solder to that (ie make the whole trace redundant).

If you have small breaks and you want it to be kind of pretty, then breaks can be bridged with small bits of tinned copper wire, after scraping off the mask from the traces, but if you don't care about any of that, just make life easy for yourself and solder an insulated wire between the terminals of the actual components themselves and dont bother trying to solder anything to the trace itself.

 

[500e]

Clean the board, break cleaner & soft tooth brush work, remove the lugs of the switch that could to be in the (holes, see bold print)
Solder wick to remove solder when molten I prefer a reasonable sized iron 25W for that sort of switch with a 1/16 chisel tip remove all solder from through holes clean solder repair wire to track with loose end through hole fit switch make sure it is correct way in board re solder the 4 sw legs inc repair wire .
A small dab of super glue on wire and end of track will help to stabilize the butchered bit.
Saying all that the switch still on the board look to be surface mount (if so get correct switches not through hole,) sort of same thing to remove solder wick each leg of sw then slide a scalpel blade between the track & sw pad while heating Do not force anything. then clean board again.
Heat + time is the killer of track adhesion, that's why I used the bigger iron quick heat less soak time, or you can use a hot air iron but first buy one then practice on a gash board.
Surface mounts usually have more fragile track than through hole, be careful.
Gave all my sheets of track away to a mate in Germany so a strand of tinned wire out of a mains flex will do the job.
A coat of clear nail varnish over new track and solder pads will help to stop corrosion as next sw is showing
You want 22/24 swg solder

 

[dobbslc]

Ok I've had a good go of it and had to bridge a track, I managed to get the switches on and connected but it wouldn't turn on. I tested the switches were actually working and connected by probing the tracks and pushing the buttons and I got continuity on and off.
The tracks were already pretty mashed so worth a try

 

[500e]

Is it totally dead if so look for a surface mount fuse
Was it surface or through hole

 

[mtt.tr]

Ok I've had a good go of it and had to bridge a track, I managed to get the switches on and connected but it wouldn't turn on. I tested the switches were actually working and connected by probing the tracks and pushing the buttons and I got continuity on and off.
The tracks were already pretty mashed so worth a try

Better to try than just bin it.

 

[awemawson]

Silver loaded conductive glue sometimes digs you out of the claggy. I’ve used it when conductive keyboard pads have worn off on cnc machines, and when tracks have become detached. RS components sell it.

 

[dobbslc]

Is it totally dead if so look for a surface mount fuse
Was it surface or through hole

It is surface. What does a surface mount fuse look like?

 

[Alan Reynolds]

That’ s a Mychron 4 by the looks of it. They usually suffer from water ingress and that does the switches in. They are surface mounted so you have to modify the legs of the switches.
They have to be the same height as the ones you remove. Otherwise the cover presses the switch.
They are easy to do, so long as people who aren’t used to dealing with them, don’t attempt a repair.
The tracks are very delicate. They don’t use all four legs, just two to make a switch.
A bad switch that has water damage will conduct and prevent the unit working sometimes.
Concentrate on getting the ON switch to work first. Then if it lights up, move on to the others.

 

[500e]

https://uk.farnell.com/c/circuit-protection/fuses-fuse-accessories/fuses/smd-fuses

There's a selection the left hand white strip has holes for 6 x 3amp fuses but 10amp could be same size
Each line on mat is 10mm

as

 

[dobbslc]

That’ s a Mychron 4 by the looks of it.

You are correct!

They don’t use all four legs, just two to make a switch.

Yes I worked this out, unfortunately even though the new one was working it didn't want to switch on, the tracks were already well knackered

 

[Alan Reynolds]

You are correct!



Yes I worked this out, unfortunately even though the new one was working it didn't want to switch on, the tracks were already well knackered

I know you probably know this already but you may have to hold the ON button down to wake it up. This is to prevent accidental switching on.

 

[dobbslc]

I tried all combinations of press and hold etc, it's dead though.