On 2005-05-23 email@example.com said:
>Michael Pardee wrote:
>>>>>Bought an '87 Accord hatchback recently (2.0l, 2bbl, 5spd)...
>>>>>owner was selling it because the alternator "didn't work".
>>>>>Seemed to me that it worked, but not 100%. In any case, I
>>>>>swapped in the alternator from my identical '87 sedan that had
>>>>>just bit the dust, and all was happy until a couple nights ago:
>>>>>charge light flickering, dashlights dim, except when revving
>>>>>high. Typical indication of bad brushes. Figured I was doing
>>>>>okay trying to get home when suddenly the charge light came on
>>>>>solid and wouldn't go out for anything. JUST made it home,
>engine sputtering every time I hit the brakes. >>>>
>>>>>So today I pulled apart the original alt. and checked it out:
>>>>>diodes all test fine, field windings seem okay, no opens or
>>>>>shorts anywhere. Brushes weren't too badly worn, so not really
>sure what was wrong with it. >>>>
>>>>>Got the replacement alt. out of the car (finally - some
>>>>>Japanese SOB needs a serious bitchslapping over the layout of
>>>>>that engine) an opened it up... brushes were REALLY worn, but
>>>>>still making contact - barely. Diodes and windings checked okay
>as well. >>>>
>>>>>Now the only thing I can't test is the voltage regulator. Or
>>>>>can I? With a stanard multimeter, that is, since I don't have a
>>>>>nice super-duper alternator/starter bench tester sitting on my
>kitchen table...? >>>>
>>>>>I took a few readings across various terminals of both
>>>>>regulators, DMM set to Diode Check, and got several readings
>>>>>that differed between the two... for example, testing from
>>>>>"terminal A" (named arbitrarily for the sake of argument) to
>>>>>terminals B and C on one regulator showed infinite resistance,
>>>>>but on the other, they showed about 1200Mohms aa 1800Mohms,
>>>>>respectively. Reversing the leads, the first regulator showed
>>>>>1200 and 1500 (B-to-A and C-to-A), but the other, I got 1500M
>>>>>and infinite, respectively. Obviously I don't know which one
>is "right" reading, and it's not enough to make an intelligent
>>>>>diagnosis. >>>> So... does anyone know of any way I can test
>>>>>the regulator? Or better yet, know how I can hook up the
>>>>>alternator on the bench (ie. what goes to what connections) and
>>>>>test it there, maybe spin it up with my cordless drill?
>>>>There isn't any great way to test it on the bench with common
>>>>tools - it is a lot easier to test it in service with a DMM.
>>>>However, most major auto parts stores have a test jig, where
>>>>they can spin the alternator with an electric motor and measure
>>>>the output under various loads... and they will do it for free.
>>>There must be some way to test the regulator module itself -
>>>supply juice to the inputs, measure the outputs? As I say, all
>>>the other components are fairly "testable" on their own and seem
>to be fine... >>
>> Maybe, but I'm not sure. Some old voltage regulators used analog
>>drivers, but I think all of them now are switch mode, pulsing the
>>inductance of the field. You could connect the regulator to the
>>alternator and measure current drain as you turned the input
>>voltage up - the current should drop rapidly as you exceed the
>regulator point (somewhere around 14 volts).
>Cool, except it still has to be in the car for that, which in
>itself is a nightmare, and at that point is wholly inaccessible :)
>Assuming one determines which connections are which on the thing,
>I guess that's what I'm really hoping, is to find the pinouts for
>the module; given those, I may be able to at least tell, without
>putting it all back together and into the car, whether either of
>the two regulators I have are *obviously* faulty.
>Recall that the original alternator in the car worked
>intermittantly, and upon disassembly and testing, the brushes seem
>sufficient and everything else I CAN test (windings, diodes) seems
>good, so that leaves the regulator as "questionable".
>The behaviour of the second one worries me a little, the way it was
>doing the typical worn-brush thing for only a little while before
>packing it in completely: again, the brushes are obviously gone, and
>everything else tests fine, and I don't want to put it all back
>together and into the car only to discover the regulator is pooched.
>A simple works/doesn't-works test is all I'm looking for.
Is there anything wrong with taking your alternator to a parts store
for testing on their machine? Next town over has a Checker parts
store with at least one real competent guy who would test yours.
near Mountainair, (mid) New Mexico, USA
Sure it's funny! Now beam my clothes down Scotty!
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