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What's a good method for a non-technical person to short the terminals of two 0402 resistors ~1mm apart? (lemmy.world)

submitted 1 month ago by [email protected] to c/[email protected]

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I'm working on a mod kit for a popular item, but my target audience isn't likely to have a soldering iron. The majority of the project connects to an exposed ribbon connector, but I need to short two terminals to force a power supply on.

Any ideas on a method I could provide for people who can't solder? Maybe a strip of copper tape?

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[–] [email protected] 4 points 1 month ago

Looks like a basic soldering job, give it a touch with resin and fresh solder and create a blob. Even my non-technical grandpa (in his 30s, he needed his 3yo daughter to operate a cassette deck for him!) had a soldering iron for some reason in his shack, and it's a good skill to have.

I'd need measurements or a better picture but it looks like they might be connected to adjacent pins (3 and 4, where 1 is on the right side from our POV) on the FFC connector. I would try to target that first, there are several options if that is available:

wrapping both in a loop of thin wire
wedging a metal item or piece of pencil lead in between (could damage the connector by bending pins if it gets reopened, or the item could dislocate)
adding a thin strip of conductive foil to the cable's pins before plugging it in
on the less-fragile flat cables that use real copper or aluminum strips, the insulation can be reliably removed on the traces in question using gentle force, and then the exposed conductors could be bridged with aluminum foil pressed against the cable by a paperclip, then taped over to prevent accidental shorts. Works with non-adjacent pins too, and can be used on PCBs if you can remove the solder mask on traces near board edges.

Speaking of the last method, you might not need a board edge nearby if you can rely on pressure from the device's housing:

Use a knife to gently scrape the solder mask off the traces in question, preferably far from any components.
Cut a piece of aluminum foil into a shape just big enough to cover both pads.
Use transparent tape to stick it to the board at the right spot.
Find or make a foam pad (or similar) of appropriate thickness (which can be determined using modeling clay) to place between the PCB and the housing/bracket/screw. You can use tape to keep it at the spot while reassembling the device.

If applicable, remind them that when screwing screws back into plastic, it is necessary to twist counterclockwise first to locate the original thread and not make a new one, which could ruin it.