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George, I think this is in the ballpark of what you are looking for... was on SwedishBricks list yesterday:
Message: 68
Date: Mon, 06 Jun 2005 11:04:16 -0400
From: Mark <1980_244@primatesynthesis.com>
Subject: [SBricks] diy 240 instrument voltage regulator replacement
To: bricks@lists.swedishbricks.net
Message-ID:
Content-Type: text/plain; charset=us-ascii; format=flowed
So I replaced the instrument voltage regulator on my 1980 244. It is
this zinc-yellow rounded rectangle, that sort of looks like a an
upside-down bathtub, that is about an 1 1/2" long, and 3/4" wide. It
plugs into the back of the instrument panel, behind the fuel and
temperature gauges. Mine was stamped 394.051/003/001.
Even though I had I read about it, I was still shocked when I opened
it up and found that it contained no electronics. It is a MECHANICAL
voltage regulator!! It has a coil and a set of contacts (similar to
a set of points in a mechanical ignition). The points were dirty,
and the coil was covered in black carbon.
So I decided to replace it with an electronic regulator I built
myself. This cost me less than $5 in parts. I got the idea from this
page:
http://www.164club.org/spanreg.html
The circuit on that page uses a 7810 fixed regulator. Although, imho, the
inclusion of the 10 nF input capacitor isn't going to make a difference.
Anyway, I did not have a 7810 so I used an LM317T, and built a new
circuit on a piece of perf board. The 317 is an adjustable
regulator, so I had to include a few resistors in order to set a 10V
output.
While I did use a 100nF input capacitor, I did not use an output
capacitor, as I'm quite sure that the output of a solid-state
regulator is far more stable than the archaic device I was replacing,
and considering the way this mechanical regulator switches on and
off, either there is a capacitor already in there, or it doesn't
matter.
I added three leads to my circuit (input, output, and ground).
Crimped on spade connectors. Plugged them into the back of the
instrument panel. Wrapped the circuit board in electrical tape, then
taped the whole thing into place.
It was convenient that there was a connector for ground, as the the
ground terminal isn't connected to anything inside the old regulator.
I used an LM317T because I already had some. While using a 7810 does
not require resistors, for bricksters in the U.S., building a
317-based regulator might be more convenient because Radio Shack
sells 317's and all of the required parts, but does not sell 7810's.
However, if you prefer the simpler circuit, you can get a 7810 from
Mouser, Digikey, etc.
Here is an LM317T calculator to determine the resistor values. In
practice, I found it wasn't entirely accurate, and using a car
battery and a voltmeter, I adjusted the value of R2 until I got 10
volts.
http://www.electronics-lab.com/articles/LM317/
This page has some information for 240's using newer regulators:
http://www.brickboard.com/ARCHIVES/1998JUL/20006587.shtml
--- end of SBricks message ---
As for me, I regret understanding only about 1 out of 3 words of the above. Oh, well... yesterday I drove my older daughter to the U of M for a summer internship, and, while I am academically challenged, Erika praised me for my ability to pack the car. :-) Take what you can get.
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