Dash foil repair, it CAN be done, but it ain't pretty

[keithwwalker]

Who says you can't solder to a dash foil?

The method I use is to get one of those Cold Heat soldering irons and some .015 inch silver bearing solder from Radio Shack.

It takes practice with the cold heat gun, but if you have exposed metal foil, you can melt a bead of solder to build up a little ball. Once that freezes, then carefully take a length of solder wire and solder or melt that to the little ball on the foil. You do the same on the other end and you have bridged the gap.

In this photo, my foil had formed a gap behind the tachometer:

It is delicate work, but you can repair an otherwise useless foil that has a short in it.

My 85 dash had a recurring problem with the speedo light, so I cut away the shorting section and bridged the gap with some solder:

I was a bit lazy with the length of wire, but I can always trim it down and resolder.

Remember to use silver bearing solder so it has good electrical conductivity.

[goffoz]

In my line of work I use Oxy/propane ,propane,hydrogen, electric induction
and recently we went to laser...but whats "cold heat"
....never heard of it

[gt8]

[keithwwalker]

Yeah, you did it on those late night tv infomercials.

Best I can tell is that it uses a two sided tip made of carbon, or a mix there of. It is a variation of resistance soldering, only it is inexpensive.

Here is a really great article about it:
http://www.pcmag.com/article2/0,1759,1750090,00.asp?kc=PCRSS03079TX1K0000585

You touch both tips to what you want to solder by placing both the solder and work piece in the center of the tip(very tricky!); and I believe a tiny induction current flows. There is little excess heat, less than a regular solder gun.

http://www.coldheat.com/NR/store/index.cfm?action=cat.prodInfo&productID=76

Home depot still sells them and the tips under either the Cold Heat. I think they were sold under the Weller brand for a while.

Cold Heat is a great idea, but it isn't too popular because you don't use it like a normal soldering gun. And it is hard to work with.

[keithwwalker]

[stevey88]

This thing has several volts across the tip. I will not solder anything with integrated circuit with it. Take it from an EE with over 30 years of experience in Semiconductors.
_________________
Steve

87 Westfalia full camper 4 speed

[reiney]

Another good thing to use for foil repair is wire-wrap wire. Radio Shack used to stock it but no more ... It is 30 ga. tinned with a fairly tough, heat-proof insulation (Kynar, I think ...). I solder it with a cordless, fine point soldering iron with a hi-temp tip.

Hardest part is stripping the wire without nicking the conductor.

[tencentlife]

Hate to nitpick, keith, but those things you repaired were open circuits, not shorts.
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Please don't PM here, I will not reply.

Experience is kryptonite to doctrine.

[keithwwalker]

You are right about the open circuit behind the tachometer.

But the speedo light was a short, I could touch the foil before the repair and the light would flicker, but the foil would also spark. This was magnified when I still thought it was an open circuit and I painted some conductive paint back there (defroster repair kit stuff). The resulting light show was interesting, conductive paint lights up when it shorts out, lol.

So basically I cut out the shorting area, making an open circuit and bridged it.

[tencentlife]

Aha.
_________________
Shop for unique Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/

Please don't PM here, I will not reply.

Experience is kryptonite to doctrine.

[psych-illogical]

[westyventures]

www.mcmaster.com sells a special conductive epoxy for just this sort of repair. My bro uses it all the time on his antique Mercedes.

[Perales]

[keithwwalker]

Yeah that defroster paint is conductive.

[keithwwalker]

You raise an excellent point, something that this ME didn't think about. AFAIK, the dash foil only has some resistors?

Still it worked and the cost of failure was the same as not fixing the foil - ie, throwing it out.

[TremcladWhite]