Marc Rising Star's Tech Answers - Answers for Questions relating to VINTAGE AUDIO EQUIPMENT © 2001-2014 Ultraelectronicactive.com* Vintage Audio Equipment Printed circuit boards |
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Question:I have have a printed circuit board (PCB) that has cracks (open traces) and needs to be replaced. ©2008 ultraelectronicactiv.com Answer: In most cases PC boards for vintage audio gear are obsolete and the only option is to repair. The only reason for not attempting to repair the board would be, if corroded or burned up in so many areas that a repair would not be feasible. And yes I did have to reject a piece of equipment once with a bad PCB, because a cat had barfed into it and that ate away a lof of the copper traces completly in several areas. But In vintage audio equipment most boards are single layer, so quite repairable! Cracked boards can be repaired with liquid crazy glue from the non conductive / compoents side of the PCB: Let the crazy glue seep into the crack to fill it in and rejoin it. And then at the oposite side of the board, on the conductive or solder side: scrape the sealer form the trace on both ends from where the crack is, to expose the copper of the trace. Tin with solder and then solder a jumper wire bridge with wire wrap wire (about the thinnest readily available); cut the wire with a razor after soldering i, which makes it easier to position it; and work as thin and small as possible, as not to create short circuits to other traces) |
The previously open trace now conducts again. Often solder alone will do to re-connecting of the cut trace, but solder is soft and may open up again, if the board gets exposed to mechnical stress. To do it perfect: use wire. Of course: trace repair has to be done throughout the entire board, trace by trace until all open traces conduct again. A friend of mine came to me last year with a vintage late 1970's Yamaha keyboard string sythesizer that had been thrown out, as it had been dropped and a couple boards had cracked in several places. It seemed in pretty bad shape. Aparently the tech working on it had given up. This was the worst cracked board I had ever seen, so it took about 25 places where traces needed to be repaired over two boards, plus a bunch of re-solder of aged brittle solder points were needed, but after the re-work the synth fired up again, and after a few more maintenance items, such as contact cleaner on all pots and switches plus a few push button switches replaced, this instrument re-joined the ranks of the fullty living instruments again! Restored to it's full glory - in every aspect working again! Repairing the board: well worth the effort!2008 ultraelectronicactiv.com Vintage Audio Equipment For Sale More Tech Answers • Star's Vintage Audio Equipment currently FOR SALE |
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