Lotus Elan

Heated rear screen - baffled

PostPost by: NYK » Wed Feb 20, 2019 1:40 pm

I needed a heated rear screen for my Plus 2 restoration. I could only find an early (vertical element) screen in need of some work. The elements and the top and bottom horizontal connecting bars appear unbroken, they are bronze in colour and appear to be just under the surface of the glass not surface printed. Above the horizontal connecting bars is a surface printed silvery electrode. The silvery surface layer is in poor condition and needs to be replaced. I can show electrical conductivity along unbroken parts of the silver electrode but cannot demonstrate any conductivity along the bronze heating elements.
I?m sure the bronze elements are not surface printed because in places I can see scratches in the glass across the heating elements but using a high powered lens can see that whilst the glass is scored the element is clearly intact and uncut, also if you run your finger nail over these heating elements you can?t really feel any edges as you might expect if it was surface printed.
So here is where I get confused! If I am correct in saying that the bronze elements are under the surface of the glass, how can this make electrical contact with the surface printed silver electrode and if I?m wrong and the heating elements are surface printed why can?t i measure any resistance along their lengths?
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PostPost by: Craven » Wed Feb 20, 2019 2:41 pm

If it?s a laminated screen the element can be between the two layers, look for a connection along the edge near the silver patch.
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PostPost by: NYK » Wed Feb 20, 2019 3:04 pm

Craven wrote:If it?s a laminated screen the element can be between the two layers, look for a connection along the edge near the silver patch.


I?ve try to photo the screen so you can see what I mean. The contacts for the supply voltage are at each end of the screen, current flows into the top horizontal bar and flows through 12 screen elements to the bottom horizontal bar (not in shot) and then flows back up the other 12 elements to the top horizontal bar, which of course has a break in the middle as seen in the photo. There are no obvious edge connectors.

d6015fab-85e7-47bc-a6fd-9ef008f61529.jpeg and


You can see how the silver layer overlays the bronze, for it to work current has to flow from silver to bronze, If anyone has one of the screens and a multimeter I would be interested to know where you can measure conductivity.
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PostPost by: Craven » Wed Feb 20, 2019 3:47 pm

If it?s a single sheet of toughened glass, may be you are just seeing a ghost of a long gone element, the ones I?ve seen have been detectable with a finger nail, surface printed.
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PostPost by: NYK » Wed Feb 20, 2019 5:00 pm

Yes, perhaps you are right, I had sort of assumed the silvery colour had just been on the top and bottom bars, but I guess there is no reason to suppose it did not also cover the bronze colour and in fact thinking about it, there is every reason to suppose it did! Bugger looks like I?m in the hunt for another heated screen which seem to be as rare as rocking horse whatnot.
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PostPost by: Craven » Wed Feb 20, 2019 6:03 pm

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PostPost by: NYK » Wed Feb 20, 2019 6:58 pm

I guess if all else fails that?s a possibility. Not directly available is the U.K. of course
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PostPost by: Bud English » Wed Feb 20, 2019 7:54 pm

Craven wrote:https://www.frostfighter.com/clear-view-defrosters-about.htm


I'm sitting here with two rear windows, one with and one without the defroster, and hadn't made my decision on which to install when the time comes. I broke a connection tab off removing the working, original, heated screen. Knowing that these repair component pieces and supplies are available (see their catalog pages) gives me options. Thanks for that posting.
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PostPost by: 69S4 » Thu Feb 21, 2019 7:21 am

Craven wrote:https://www.frostfighter.com/clear-view-defrosters-about.htm


Just need to come up with a hacked version of their products to deal with Stromberg carb icing :lol:
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PostPost by: Chrispy » Sat Feb 23, 2019 12:53 am

On my early plus 2 it had horizontal heating elements, however they were in very poor condition. They were surface mounted and most were broken. I scrapped them all off and it looks MUCH better. Not much use if its cold and damp, but that's not common where I am :lol:
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