

| Subject: | Re: Instrument Cluster Printed Cirucit repair |
| From: | David Beierl |
| Date: | Fri, 18 Mar 2011 16:56:10 -0400 |
At 03:51 PM 3/18/2011, Scott Daniel - Turbovans wrote: >is anyone repairing that one spot...where the plug plugs on ? The strips of >copper get ripped or damaged there ........which is why I always lube and >treat that >connection. Repairing that particular spot would be quite a difficult repair, better to cut the damaged part off, carefully skive off little windows in the plastic layer *on the thin side* exposing the foil, clean and very delicately solder wires there and secure them to the remaining tab of flexible circuit and run them to a DB25 connector. As long as you keep physical stress of the wires where they solder to the individual foils on the flexible circuit your connector troubles will be over as the DB25 is a very robust connector. You can get them with crimp pins that insert into blank shells, or fixed pins with solder tails which I recommend for one-off jobs like this. Suggest wiring up the connector first, using flexible wire and paying *serious* attention to securing it so that no stress can ever come on the panel joints. Use thin flexible wires, maybe 22-ga stranded. Double up if you need more current capacity rather than using a thicker wire. Practicing with a junk flex-circuit if you can would be very good - you need to tin the foil very quickly, tin the wire separately and generously, then apply it to the foil and quickly heat it to fuse the two. Gently scraping the foil shiny-bright will let it tin easily. The foil has practically no mass so it will heat very quickly, and if you're careful you won't damage the polyester backing too much or more likely cause the delicate copper foil to lift from the backing. Use something to glue the raw edge shut where you cut the ruined part off, so it won't tend to delaminate from there. Acetic-curing silicone RTV is not ok. A bead of hot glue could be great. Since there are 14 pins on the connector, DB15 would work fine too. Yrs, d ps - I've only had one delaminated flex-circuit to play with. I had partial success in relaying the wires and reactivating the adhesive holding the layers together, using an iron set on polyester. Spraying one side with 3M 88 spray adhesive might work better but I bet it would be absolute hell to get it assembled without disaster. Iron-on fabric repair scrim could be a much better choice. Regardless, this is finicky delicate work. Takes patience, calm, willingness to do the fixturing over and over until everything is right and stays put before putting the heat to it. Working progressively from one edge of a delaminated spot to the other, lining everything up with a rolling weight for 3/8 or half an inch, then coming behind with the iron to seal that much; rinse and repeat will be the method that works.
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