Bad Regulator -- Again!

[Tom_Veatch]

Are the regulators on these machines a weak link? I'm replacing the one on my YM2220D for the second time in a year (with less than 20 hours on the last one).

Symptoms were/are:

• Alternator light is on constantly for any engine RPM from 0 to red line.
• Voltage across the battery terminals is the same (~ 12.5 volts) with or without the engine running. (Verifies no charging current reaching the battery)
• With the engine at about 1200 RPM and the alternator electrically disconnected from the wiring harness, the alternator is showing about 14 VAC. (Verifies the alternator is functional)
• With the alternator disconnected, the resistance between the alternator terminals on the regulator shows 0 ohms. (That don't seem right to me)
• With the alternator plugged into the wiring harness, the alternator wires get uncomfortably hot to the touch very quickly (Indicates a high amperage which seems to verify the alternator is passing current through a low resistance load).
• Voltage from the battery charging current output terminal on the regulator to ground is 0 VDC . (Now, I know that ain't right - should be numerically close to the alternator VAC output.)

So, I'm replacing the regulator - again! What should I be looking for that could be causing the repetitive failure of these regulators?

 

[tommu56]

Tom

most regulators control the field current in the alternator to control charge current.

I would look for an auto electrical repair shop that actually repairs starters and generator and alternators take regulator and alternator to them.

The ones around here are way cheaper for repairs than tractor dealer (he probably takes it to them any way) or new one.

the other choice is to put a chevy one wire alternator in.


tommu56

 

[kenmac]

Yep, Have the alternator checked . Or, you may burn out another rgulator

 

[Tom_Veatch]

most regulators control the field current in the alternator to control charge current.

Keying off your word "most", I'm wondering if that's truly the case here. From the tractor's wiring diagram and the measurements I've made, it looks like the regulator is simply a rectifier and logic control device for the alternator "idiot light" on the panel as well as a DC power source for the other indicator lights.

There are two conductors between the regulator and alternator. I'm measuring the AC voltage between those two conductors. It seems like there would need to be at least three conductors if the regulator controls alternator field current. I've assumed both conductors are electrically isolated from ground. Don't know that to be the case but will test that assumption tomorrow. I'll also look at the alternator output over a wider range of engine RPM. It it doesn't vary much from the 14VAC point over the full RPM range, I'm going to guess that it's internally self regulating.

I'm certainly no expert, nor do I have a schematic of the regulator, but it looks like those two conductors carry AC power to the regulator where it is internally rectified to DC and fed to, for lack of a better nomenclature, the regulator's charging current output terminal. That terminal provides charging current to the positive terminal of the battery via a common connection at the starter solenoid.

the other choice is to put a chevy one wire alternator in.

Now that is an intriguing suggestion. Do you have any references/suggestions that might be useful if I wanted to go that way? I assume the "one wire alternator" is self regulating and has internal diodes to rectify the AC to DC. Maybe with a little ingenuity, I could come up with a way to power the instrument panel without the control circuitry in the stock "regulator".

 

[reb]

This thread discusses the 1610 regulator. I suspect yours operates the same way.

www.tractorbynet.com/forums/yanmar/49205-1610d-volt-reg-wells-vr728.html?highlight=1610+regulator

Before energizing your new regulator I would carefully check the wiring for intermittent shorts and also verify all connections are clean and tight.

 

[tommu56]

tom
here is a link for 3 wire ones

Catalog

my local starter shop converted my wives 74 nova alternator over to one wire it was just a different part in alternator the rest of it was good cost about $20.00 20 years ago.


Edit

here is one on ebay
eBay Motors: HIGH OUTPUT CHEVY ONE WIRE ALTERNATOR 105 AMP (item 130152219327 end time Sep-16-07 22:07:46 PDT)
tom

 

[FL_Jerry]

Might want to check this out: Alternator and Generator Theory


Also, there is a link there for the pro vs cons of 3(4 with gnd) wire vs 1 you might want to consider.


FL_Jerry

 

[rock2610D]

Not sure this will help but I will give you my experiance with Alts and Regs. I fought this type of issue with my bronco. Its regulator had a ground wire that attached to the screw that held it to the body of the truck and the body was grounded to the motor then battery.

Problem was that the location where the regulator was hooked to body was a little rusted and the ground wire was not grounding the regulator. I had to take sandpaper and clean all surfaces where the regulator attached to the body and then cleaned the ground wire from regulator to the screw.

BAM all my problems were fixed.

 

[Tom_Veatch]

This thread discusses the 1610 regulator. I suspect yours operates the same way.

www.tractorbynet.com/forums/yanmar/49205-1610d-volt-reg-wells-vr728.html?highlight=1610+regulator

Before energizing your new regulator I would carefully check the wiring for intermittent shorts and also verify all connections are clean and tight.

Thanks, Reb, for the link. Interesting discussion although it rapidly got a lot deeper than I could follow. My knowledge of solid state devices is limited to what I remember of a couple of college physics courses from the mid 60's. But, best I could understand, sounds like they were talking about my "regulator".

 

[Mickey_Fx]

Have not had any electrical problems on my tractor so no firsthand experience. From what I've read and looking at the schmatic, I'm with Tom on these systems.

The alt produces A.C., no rectification internally and has permanent mags for the field. The "VR" rectifies the A.C. and shunts the excess current to ground to control the voltage. This is not unlike many/most small engines found in lawn and garden tractors.

This is not your typ auto alt.

My rememberer may not be working correctly this AM.