RWD - Exciter wire voltages

Volvo RWD 200 Forum

INDEX FOR 9/2019(CURRENT) INDEX FOR 7/2013 200 INDEX [<<]  [>>]


Exciter wire voltages 200 1981


Ok Tim I think you are obsessed with this “exciting” issue of a thing. (:-)

We as a non technical group don’t get into this but Art Benstein does here!


I put this on here so you can see the dash, switch, battery, firewall connector... the whole she bang!
If you so dare or need to, go ahead and study this to trouble shoot things.
Like you said, the other end of that exciting wire is entertaining us!
Now to most of of us, it looks like some strange Artist work! But it’s just Art, trying to help us in the 240 section.

You have raised up some good thoughts especially the part of how am I getting more volts that the battery has! We both know there is no step up transformers here, so why?

Well, some how you have picked up on the AC side of things going on inside the alternators windings. His diagram shows the back feed circuit to the regulator and how it’s the middleman over to the rotors slip rings.

There is actually more voltage being generated in the windings because as the voltage/ current pluses pass through a diode, the voltage drops across the diode. So there needs to be more!
This is Very similar to a resistor and it’s about .7 of a volt drop.

An open or shorted diode will pass no voltage or will show voltage with no drop from its input!
It is an actual method of tracking or troubleshooting a circuit for damage. Especially, if a transistor has failed in electronics. Some look for gain but it’s not in voltage but signal gain.
That is, if you have the right kind of voltmeter, called an oscilloscope. It shows peak to peak volts in AC.
A regular voltmeter use a Root Mean Square readings for AC readings.
This Gets me, that it is the same math as a sine for a 45 degree angle ... .70746. I have that memorized!
30 degrees is .5. Machines move with right angle coordination within a Cartesian space.
Electronics will always elude me as my last frontier! So many wonders, so little time!

So, that supposedly wild high reading depends on the ground point like John says. He is Mr. numbers in the thread! (-:)1982Dl*****.
We both think it is how you are reading things and we are not there to see it.

Going back to Arts diagram you can plot out the three windings and corresponding outputs through diodes.
He shows the two points on the regulator set off to the lower left corner to how it becomes the middleman.
Now Art can explain this better than I can, but just maybe, the regulator diodes are leaking through excessive voltage and raising those voltage readings.
It should not be higher than the charging system voltage but only slightly less. The light bulb has to create a voltage drop as it is a resistance.

These reported findings, from you, are throwing everyone a curve!
In electronics, Sometimes, this could be called a floating ground issue between pluses?
A term that I have not understood either!

I personally have never bother to check the exciter wire but I would only look for voltage coming through from the dash to ground only! Only off the end of the wire.
Not connected to the regulator side of the circuit on the alternator D+! When you are connected you are messing around with a voltage producer!
I have no experience, but you do!
Normal DC volts can be as high as 16 volts written on alternators.
I have read where people claim 45 volts! How they can get that, I don’t know and you don’t want to see that. It can blow out light bulbs.

Have you ever checked the alternator housing back to the battery negative post with your voltmeter?
When in parallel you should get 0.000 on the meter. Same with the positive side. You are allowed up to 0.020 millivolts of discrepancy. Above a 0.2 is serious.
Any higher then you start having resistances almost exponentially. This reading can cause and is a sign! It’s a voltage drop someplace in a whole circuit between test points.
You want to eliminate stray incomplete groundings for sure.

Remember, I said the regulator looks for TENTHS of a volt variations and makes current adjustments accordingly.
The connections/continuity of voltages thing can not be over emphasized!
This check is done with something on in the car or with the car running and having a current flow in-or out of the cable will do!

You are looking for a high resistance in any battery cables or connecting wire on either side.
In electronics the circuits are tiny and so is the tricks it does with very little power.
A car alternator is big stuff but the same principles apply.

Anyway, I think you will get the puzzle figured out and even might understand, it eventually, better than most of us! No kidding!
Answers are always on the end of questions and in the back textbooks, but they just don’t fall out when you shake the book! Getting an answer to quickly is cheating yourself!

Head scratching is allowed on the BrickBoard, so we all learn!
Interesting that John is like me, on the 240’s, as it has gotten slow over there!



New Exciter wire voltages [900][1992]
posted by  someone claiming to be Tim  on Wed Jun 5 13:49 CST 2019 >

Cut and paste link:

<< < > >>

Users marked in green are currently online.

©Jarrod Stenberg 1997-2016. All material except where indicated.

Brickboard.com is not affiliated with nor sponsored by AB Volvo, Volvo Car Corporation, Volvo Cars of North America, Inc. Brickboard.com is a Volvo owner/enthusiast site, similar to a club, and does not intend to pose as an official Volvo site. The official Volvo site can be found here.

All participants agree to these terms.
Powered by Denizen - Custom Software for Enthusiasts