bad joints

A long shot- My little battery radio developed a fault, just went dead. took apart and tested for power, all ok upto the actual circuit board tracks. While probing the tracks and solder junctions it started working. Seems that I must have re-made a joint, but don't know which. Looks impossible for me to resolder, too small. Before I put it all back together is there anything I can do ? Any sort of spray or cleaner? Or just re-assemble and hope? With apologies to all the electronics experts and for off-topic.

What sort/size of soldering iron do you have? Ian S C

Best thing to do is to closely inspect the board with a jewellers eye glass. what you are after is a solder joint where there is a ring around the component lead. This is the air gap that is stopping it working, just needs touching up with soldering iron.

Frank

Judicious prodding with a cocktail stick whilst it is on may produce crackling when you touch the component with the bad joint.

David.

Cleaned between the joints with a pick, might have helped. After using a magnifier can't see anything obvious. Will re-check the plugs and reassemble. If goes again I will have a go at soldering using a bit of copper wire as an extension on my quite large electric iron. Thanks for the ideas.

Could be a near invisible break in a p.c.b. A freeze spray would show this up by making the circuit element contract, bringing the fault on, thereby localizing it.

Maurice

You may well have already resoldered a dry joint. All joints should look bright and shiny, not dull and crystalline.

If you do find a crack in a track on a pcb, you may be able to recover it by soldering a short piece of copper wire across the break, (This may reinforce the board and reduce the risk of repeats elsewhere). Stating the obvious, do take care not to bridge adjacent tracks when remaking joints

Howard