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Posted by: jimkelly Jul 6 2009, 04:40 PM

why did my wire from my coil to my points/condensor fry - up in smoke : (


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Posted by: messix Jul 6 2009, 04:47 PM

the rear relay board harness plugged in one set on pins to the rear too far?!


i've done it..... same thing happened to me.



oops didn't read it right.


shorted condensor.

Posted by: Project 6 Jul 6 2009, 05:03 PM

Something grounded out. You're gonna need a Fluke Meter....

Posted by: jt914-6 Jul 6 2009, 05:17 PM

The condensor wire should be connected to the negative side of the coil with the black/purple stripe tach wire. Is it connected wrong in the pic?

Posted by: 914Sixer Jul 7 2009, 12:38 PM

In George's Tech Tip book page 84, 621:

Never leave the key in the" on" position. If the ignition points happpen to be closed, they will casue the coil lead to short and melt the ignition harness.

Posted by: jimkelly Jul 7 2009, 01:33 PM

dang : (

appreciate the explanation though : )

jim

Posted by: Cap'n Krusty Jul 7 2009, 02:39 PM

That's bullshit, although it "may" overheat and damage the coil after a while or cause the points to fuse. The points are a ground circuit. The positive side of the coil is a 12v + circuit. The ONLY way you're gonna melt the ground circuit is to apply 12v + to it, which is what happened here. The tach wire in the harness is melted, too, and possible the other wires bundled with it. It's likely that the 12v + wire was mistakenly connected to the point side of the coil, or the point and tach wires were connected to the + side.

The Cap'n

Posted by: jimkelly Jul 7 2009, 03:16 PM

i could have sworn that i did not move this wire from one side of the coil to the other - is it possible the car could have run with this wire on the positive side of the coil? cause it was running but i was having trouble with getting fuel pump to operate.

i just ordered some crimps and a good crimp tool - to fix this issue.

also - is the right side of the coil label always the hot side - without pulling it out of the car - i can't see + -

edit - i just pulled it and marked it with a sharpee.

so condenser wire (now fried ) goes to neg side of coil.
i have on remaining fried wire - you think it is my tach wire? thsi goes to neg or pos

what is the remaining good black wire? this goes to neg or pos?

my oil pressure switch is busted - that is my green/red wire - correct?


jim


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Posted by: Spoke Jul 7 2009, 03:57 PM

Don't use crimps for electrical connections. They loosen and oxidize over time and cause intermittent opens.

Slide on a length of shrink-wrap tubing, strip the wire ends, twist together, solder, slide shrink-wrap onto connection and heat the shrink-wrap.

It's a little more involved but you'll never have a problem with any of these connections again.

When I sold my 914, the license plate lights were out. I chased the problem to a crimp connection in the tunnel. Move the crimp and the lights go on; move it again and lights go off.

Strip wires, twist, solder, shrink-wrap; a problem never more.

Posted by: jt914-6 Jul 7 2009, 04:05 PM

The condenser wire and the tach wire (blackW/purple stripe) go to the negative side of the coil.

Take a test light and see if the "black" wire is hot with the key on. If so, that wire goes to the positive side of the coil.

You may have to peel back some of the sheath to determine which wire is the tach wire (black/purple).

Posted by: Cap'n Krusty Jul 7 2009, 04:05 PM

Soldering is NOT recommended for automotive wiring. Proper crimps using non-insulated connectors, then encased in shrink tubing where necessary, is what all the European manufacturers recommend. In fact, they specifically forbid soldering on newer cars. Insulated crimp connectors are just as bad as soldering.

The Cap'n

Posted by: jimkelly Jul 7 2009, 04:15 PM

i am going this route.

http://www.914world.com/bbs2/index.php?showtopic=82534&hl=crimping++tool

i pulled back the harness sheathing and the fried wire goes all the way to the split at the rear fire wall. i may just run a new wire from the 12 pin connector. i have harnesses i can rob from.

thanks gusy !

jim

Posted by: underthetire Jul 7 2009, 04:19 PM

I
Get the good ratchet type crimpers with the jaws made for non insulated connectors. If you worry about corrosion, you can put a little dielectric grease on them.

Posted by: charliew Jul 7 2009, 04:34 PM

Cap'n you will have to give me a real good explanation of how any compression fitting on a wire is better than a soldered connection. I have been using soldered connections on everything I connect electrically for 40 years and have had much better reliability with solder than a crimped connection. I know for a fact that corrosion happens inside a crimped connection. Also the connector is much stronger when the wire is pulled on when the connector is disconnected. I remember the deal about acid core solder but that is known to damage any circuit and it's components but we are of course talking about rosen core solder. All circuit boards have their components soldered on.

I am very interested in your facts on your crimp versus solder connections or a link to your information. I will also search the web for this info as I am not aware of any new info about what you are stating. But that really would not surprise me as I do live in my on little world.

http://ocw.weber.edu/automotive-technology/ausv-1320-automotive-electronics/9-wiring-repair/soldering

This only explains to correct way to solder a terminal on.

OOokkay it seems the change from the good ole stuff to leadfree stuff is the deal.

http://www.ko-ki.co.jp/technical/05.html

I'll just stick with what I know works thank you. The only problem I forsee is the real solder availability.

Posted by: underthetire Jul 7 2009, 04:52 PM

I dont know about Captn's reason. Mine is when copper wire gets old it oxidizes. Especially black shielded wire. Solder does not flow well enough to hold things together in this case. New wire solders ok, but even the rosin core flux will do funny things with moisture. Iv'e had plenty of circuit bords fail from this.

Posted by: Cap'n Krusty Jul 7 2009, 05:48 PM

Might I add the FAA forbids soldering wires and connectors, too? I can't find the article I've referenced in the past, and I'm not gonna go looking for the VW/Audi and Porsche TSBs. BTW, good crimps are made with the right size connector for the wire, and the correct tool for the connector/wire. The Cap'n

Posted by: charliew Jul 7 2009, 06:57 PM

I think I remember aircraft uses 400ac voltage and aircraft wiring usually vibrates alot. Also it's pretty easy to screw up a solder joint and a crimp is a lot faster and maybe harder to screw up. The thing it don't like to deal with on crimps is they get corroded and loose from age. The heating and cooling makes the metal loose.

For the guys that like to read this seems like my kinda place. Check out post 25. http://www.jalopyjournal.com/forum/showthread.php?t=318566&highlight=how+to+solder&page=2

Leadfree problems in the repair of electronics: Post 39

Posted by: Jeff Bowlsby Jul 7 2009, 06:58 PM

The problem with a soldered connection is vibration and the resultant localized stress to the wire at the wire terminal-to-wire interface that causes it to weaken and break off. Soldering does have redeeming value because it encapsulates the connection from contaminants including air, and makes a good electrical/physical connection, but when used at wire terminals that are fixed to components, with wire that vibrates, it also creates a point of weakness in the wiring from the vibration. The best hand-done wiring connection in an automotive environment or any environment with vibration is a solid mechanical crimp, well-crimped so that it keeps all air and corrosion out of the interface and then strain relief bridging the interface usually in the form of heat shrink tubing to minimize wire movement relative to the wire terminal.

Even better are todays factory-molded connections where the wire gets its strain relief from a molded enclosure that completely protects the wire-to-terminal connection and inherently provides strain relief. But outside of the factory, that type of conenction is not possible without special equipment.

I have no concern with solder-splicing 2 wires together when in a continuous run, even when vibrating, and protected by heat shrink, because one side of that connection is not fixed to equipment, both are free to vibrate the same. Even so, sometimes soldering to a fixed connection is not avoidable, and the only risk is that the connection may need to be redone once in awhile.

Posted by: Spoke Jul 8 2009, 12:16 PM

Well I certainly opened a can of worms by suggesting solder connections. I won't do that again.

For myself though, I will continue to twist & solder wires on my old 914. Luckily for me, I'm not an auto or avionics manufacturer and I've found many problems with existing crimp connections and have had no problems with soldered connections.

Posted by: jimkelly Jul 8 2009, 12:36 PM

i think different plans of attack work best in certain situations - thanks for your input ! jim

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Posted by: ghuff Jul 8 2009, 04:58 PM

This comes up on every auto forum.

I do soldering with heat shrink, or in a pinch extremely tight electrical tape to keep the wire stiff.


I have been driving on 15+ soldered/shrinked coil wires for my daily and it has been a year plus in a super high heat high vibe environment. Very ok.