Regulator/Rectifier Smoking!!!

[ancy]

My regulator/rectifier puffed smoke the other day and the battery doesn't charge. Could this be my problem? How do I check to make sure the regulator/rectifier is getting the right voltage from the alternator? Can I check the alternator before I replace the regulator/rectifier? How? Thanks

[NCDave]

Reg/Reg is the most common cause of lost voltage. Given the smoke you saw, I'd bet it's toast. There are some voltage checks you can do, but they are a little complicated and you need a little electrical experience to really understand it. they vary by bike, but can generally be done with a home-model volt meter.

[ancy]

Have been an electrican for 13 years, so I understand that side and have the service manual for the checks. What would have fried it? Don't want to replace it and fry a new one. The Mule runs great though, it just doesn't charge the battery.

[NCDave]

how old is it? Heat is generally the issue with reg/recs. they heat up and fry from the inside. The smoke thing is a bit unusual though. Lots of mud caked up, or underwater? They should be sealed, but perhaps water seeped in? Since you have some skill at it, it's probably worth checking the electricals.

[RCW]

Look for excessive loads in the wiring by a process of elimination using your multimeter. I generally unplug all relays and accessories, check the harness itself for integrity, then move on to the relays and accessories. Usual culprits in frying a Mule regulator is a wire grounding out with insulation scuffed or that has been pinched, or a mud filled light. Also check your key switch for internal shorting from corrosion that gets wet after a wash or rain and creates a bridge to ground.

The regulator can be checked with a good high impedance digital multimeter, with polarity and pin checks exactly as outlined in the service manual. A low impedance analog type can overload the regulator from excessive feed current. The stator, if a gas Mule, is easily checked with any ohm meter, just look for open or shorted fields.

If you have a diesel Mule, the alternator is a standard light duty automotive type and checked just like any automotive alternator.

[ancy]

What is the voltage I am looking for heading to the rag/reg? There are three yellow wires heading to it from the alternator. I understand that this is 3 phase AC.

[RCW]

An unregulated alternator will run unlimited voltage until they burn themselves out without control from the regulator, so you could easily hit 90+ volts and still know nothing, but you sure could make a parts dealer happy as they sell you replacements for what you fry.

Look for open or shorted circuits in the stator when it is not running, not running voltage.

What you are looking for in testing the regulator are the impedance values listed in the service manual. It gives them by pin and the order the test probes must be in while doing the test to avoid damage to the regulator.

[ancy]

Checked every thing and no grounding out. Put a new rec/rag in and is charging now. When looking for the grounding things found the harness going to the speedo was cut but not grounding. It looks like this is just for the warning lights and speed limiter. I will hook it back up to see if it all works.