Testing Diodes

[Ken1]

Is the attached photos the original diode (rectifier) setup for my 86 Chiefton. With the ignition off, no shore power, generator not running and both batteries connected I have 12V on both sides of all 4 diodes is this correct.  Can I test the diodes with an ohm meter by comparing resistance in both directions;  high one way low the other. I assume to do this I will have to unhook the wires from one side of each diode which I would prefer not to do since the threads are rather rusted and may twist off. Which seams a bit of a wast if they are working. I am wondering about this wiring as the voltage regulator is cooked before replacing it I want to be eliminate all possible causes. It was cooked when i got the RV so i cant tell what happened to it possibly running the generator and moter with the dash switch on charging both batteries.

[DaveVA78Chieftain]

Those look more like Junction blocks or possibly circuit breakers rather than diodes.  The only diode device I recall Winnebago using is a battery isolator which was used for alternator output.   However I see you also have a AUX Battery relay which may negate the need for a battery isolator diode.

Chevrolet used junction blocks on the P30 chassis as common distribution points.

Dave

[Ken1]

Thanks Dave I just assumed they were diodes and you are correct about the relay it clicks in when I push the MOM switch. Assuming you are correct regarding junction blocks are the two terminals common (connected internally) in each block.  Any thoughts on what might have fried the voltage regulator.

[DaveVA78Chieftain]

The stock P30 chassis voltage regulator (VR) is part of the alternator.  I have to ask the question is that what you are referring to?  If so, how do you know the VR is fried?

GM Alternators
10SI = 55 amp
12SI = 66 amp
27SI = 80 amp


Now that I am at home and can blow the pictures up a bit, I can see that all of those blocks are self resetting circuit breakers.  That is why you should have 12 volts at all the posts.  They are used to distribute 12VDC power to different areas of the coach.

http://www.delcity.net/store/Auto-Reset-Circuit-Breakers-!-12-volt/p_198669


Dave

[Ken1]

Thanks again Dave.  Now the wiring makes more sense knowing they are circuit breakers.  Apparently the Alternator was changed to one with a separate regulator which is melted internally.             

[DaveVA78Chieftain]

Are you by chance saying something like this is a voltage regulator?



That is a diode battery isolator not a voltage regulator.

Dave

[Ken1]

No it is a conventional  3 lead tin box  regulator with  no voltage on the field terminel regardles of battery condition.  However if apply 12V to the field it puts out 14V.

[DaveVA78Chieftain]

OK.  Just making sure you  were not heading down the wrong path.

Dave