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rear demisters

Posted: Thu Dec 27, 2007 6:59 pm
by daveyboy20
The lines don't look damaged at all yet only one line (right a cross the middle) demists. It works very fast but its hard to see out of a one inch strip! Any ideas? Cheers

Re: rear demisters

Posted: Thu Dec 27, 2007 7:02 pm
by uzdubmwe30
count yourself lucky, none of mine work! search for the multimeter test on here, it's somewhere around, basically you get a multimeter and check the wires that way.

Re: rear demisters

Posted: Thu Dec 27, 2007 7:07 pm
by sam325is
woa only 1 working is UNLUCKY! on close inspection from the inside of the car you will be able to see the breaks in it. you can then repair them. :D

Re: rear demisters

Posted: Thu Dec 27, 2007 7:11 pm
by uzdubmwe30
conductive silver epoxy and masking tape, I can't be arsed to do mine yet

Re: rear demisters

Posted: Thu Dec 27, 2007 7:12 pm
by sam325is
i ahve done a whole rear screen before....and then decided the silver lines looked a bit :gay: so i took it to the scrap yard and got another :cry:

Re: rear demisters

Posted: Thu Dec 27, 2007 7:22 pm
by Brianmoooore
Switch the screen on, clip one lead of a voltmeter to earth, and put the other probe against the tracks, one at a time, in the middle.
The working one will give around 6 volts. The others will give either 0 or 12, depending on where the break is.
Check on the contacts at each side. One should give 0 and the other 12. Then check all the way up and down the vertical traces at the side. The problem I found on two screens I tested a couple of weeks ago was that these vertical traces had corroded away.
Now back to the horizontal tracks: On any track that gave 0 volts in the middle, move the probe towards the 12 volts + side of the screen, until the voltage suddenly jumps to 12 volts as you cross a break.
Similarly, where you found 12 volts in the middle, move the probe to the left until the voltage drops.
Mark the breaks as you go, then repair them with two part epoxy conductive paint and masking tape.
Note that if there are two breaks in any one track, this will only find one of them. Repeat the process to find the second ones, if there are any.
Be careful not to damage the tracks with the meter probe!
It's a fairly simple job to replace the screen with one from a breaker. The one I did a couple of weeks ago took about three quarters of an hour from start to finish, using only a small/medium screwdriver and a pot of silicon grease. Most of that time was spent refitting the locking strip (A job that would take about a minute, if I could find that special tool!!)

Re: rear demisters

Posted: Fri Dec 28, 2007 2:11 am
by goosiegander
very handy chaps, any hints on where to obtain conductive silver epoxy?

b regards, Goosie :D

Re: rear demisters

Posted: Fri Dec 28, 2007 5:29 pm
by uzdubmwe30
maplins bud

Re: rear demisters

Posted: Fri Dec 28, 2007 5:49 pm
by smithy318i
your local auto discount shop will sell it.

It comes in a tiny bottle with a brush attachment but dont use the brush as it's too big. I used a cocktail stick when I fixed one of my rear screens.

Re: rear demisters

Posted: Fri Dec 28, 2007 7:33 pm
by Brianmoooore
Use two pieces of masking tape to give a neat repair.