Date: Fri, 18 Mar 2011 16:56:10 -0400
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: Instrument Cluster Printed Cirucit repair
In-Reply-To: <0fa401cbe5a5$edb50860$6401a8c0@PROSPERITY>
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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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