I Hate Charging Problems!

[skippyc]

I like to use my old APO No2 meter to check diodes as it uses 15 volts in the resistance measuring cct.

[Tony Smith]

Tony, I'm 100% positive about the rotor failure and it is now repaired. 

Was it the old broken wire from slip rings to rotor widings? In australlia our indigenous Ford/GM/Chrysler vehicles were nearly all afflicted with Bosch alternators (once they gave up generators and actually started fitting alternators). I have soldered up those wires and attemtped to re-secure them with various glues, varnishes and magic potions more times than I care to remember. Most recently to repair the alternator in SWIO's VW Kombi.

Personally I'd use the one your repaired - it is goign to be good for at least another 30 years.

[Tony Smith]

I like to use my old APO No2 meter to check diodes as it uses 15 volts in the resistance measuring cct.

The next time I have to test a diode board I intend to use a 12v supply and test lamps.


Here's a funny thing. I think I may have gone over a little too far to the dark side in my use of Facebook. I spent at least a minute after reading your post trying to find the "like" button

[Justin B.]

Tony - the failure mode was that the wire just made it to the edge of the groove in the slip-ring and I think was just being held against it by solder flux or potting compound.  I was able to dig out enough compound from underneath the wire to pull it a mm or so which allowed it to terminate in the groove.  I then soldered it into the groove.  I will be using JB-Weld to fill in and secure.

I think I'm going to use the new rotor as it has a bit lower resistance windings.  Seems I read that the rotors with lower resistance will start generating at a lower RPM albeit with a small sacrifice of total output.

[georgesgiralt]

Hello
Those diodes are crimped. Twice (at least).
The first crimping is in the box, as the wire soldered to the chip is crimped to one of the terminals, and then the box of the diode to the diode board.
Sometimes, the crimping to the diode board "fails" by vibrations or corrosion and when the diode is requested to flow the maximal current, there is not enough pressure to convey it. But there is enough pressure to convey the micro to milli amps the ohmmeter provide. This is why one should test for dead diodes with an ohmmeter and then in situ with the "full mighty power" of the alternator... This is the problem when dealing with 30 years + components...

[Justin B.]

George, I agree.   Snowbum has a diagram on his site for a simple diode tester utilising a 12VAC transformer and a bulb that can be used to probe around on the diode board.  If I had not found the rotor fault that would have been my next step.

[Justin B.]

Care package got here from EME this morning so I put in the new rotor and I now have CHARGING!!!

[Justin B.]

Drained the gas tank of the year old varnish that was in there , filled with fresh gas and went for a ride!  Life is good... 8-)

I guess storing with carbs empty helped as the idle jets were not clogged but need to re-synch carbies...

[mrclubike]

I am still trying to figure out why your GEN light would illuminate with a bad rotor

[Bob_Roller]

Would the resistor that can be added  to prevent the charging system from failure if the bulb fails, have any bearing on this ??

[Justin B.]

I have not done the "resistor" mod, so no.  I'm guessing the light was coming on because there was not a complete "open" in the rotor, just increased resistance which allowed the light to come on but not enough flow to energize the rotor.

The reason I started the thread was to see if anybody else ever had a rotor that failed with anything other than as open condition.

[mrclubike]

Anything is possible when you’re talking about electricity 
I have seen things that make absolutely no sense

[Justin B.]

I know, was an electronic tech for years and have ran into a number of "head-scratchers."