1450 burns new voltage regulator instantly
 

I bought 1450 few weeks ago. As I were checking charging system with DVOM I saw that value "bounces" from 8.9 to 19.5 Volts. So I checked Voltage regulator and DVOM indicated that another of AC pins was shorted to B+ pin. So I made a conclusion that Voltage regulator is broken. But right after installing new one it burns again same way. I also installed 15A fuse on B+ wire. What could cause burning of VR's?

have a look here if you have not already, one of the guys posted this for reference in my 1450 thread:

http://www.onlycubcadets.net/forum/showthread.php?t=368

Did you test the stator like that shows? That would be my next step if you have not already.

To reply my question:


Another AC pin IS connected to B+ by solder joint so this is how it is supposed to be. I am trying to disassemble one of these regulators and draw a schematic of it.


Tero

Here is a re-arranged diagram for simplification purposes. You should have about 28 VAC on the AC terminals (at 3600 RPMs) and 13.7VDC output on the B+ terminal to ground. BTW, the Voltage Regulator HAS to be grounded. Between the V/R case and the Battery negative terminal, there should be zero ohms resistance.

There should be NO continuity between any "AC" terminal and the "B+" terminal.

I have opened VR and as you can see from pic attached AC and B+ are soldered to same copper on PCB.


http://i170.photobucket.com/albums/u...0/CIMG1165.jpg

Tero

Anyone else made same observation with DVOM?

Yes, I have noted the same thing.

On another brand of tractor that uses the Kohler K series has it's solid state regulator on the frame of the tractor. On that tractor, I was suprised to find one side of the ac output from the altenator winding was wired to the battery thru the ignition switch. If I remember correctly, that regulator only had 2 connections. This parallels your finding, now it makes sense, thanks for posting.

It would be interesting to see a schematic on what's inside of the regulator itself.

A question comes to mind inspired by this thread, did Kohler offer their charging circuit to charge a 24 volt system? Perhaps for a military application? That would explain the high alternator output and maybe the regulator circuitry.

Well, I learned something today. I just checked the V/R on my 1450 and found that the middle terminal to the RH terminal are bussed together like pictured.:bigeyes:

I am not an electrical engineer but have electrical experience. I do NOT see how this V/R is suppose to work. I would have thought the AC voltage and DC voltage would be segregated.

Well same here. I know exactly how alternator in car works. Also how AC-DC converters work. I am going to draw a schematic of this VR... And also have a good guess how it is intented to work. Basically this is an on/off relay made with a transistor. This transistor is connected between metallic case and other AC(2) input. Transistor Base is connected to AC(1) input that is also connected to B+. So every time when Base voltage goes above certain level transistor connects AC(1) to case. Stator has 18 windings and IF each of them gives one pulse this gives us 18 pulses/rev. So at 3600 RPM we get 60(revolutions/sec) * 18 = 1080 pulses per second. And this is also reason for 28 VAC voltage because every other pulse gets lost this way(half pulse bridge) so it gives about half of 28V -> 14VDC.... Schematic is a bit tricky to draw because 1. Parts inside have no numbers on them 2. Hard to get components off plastic casting... And yes with full-wave diode bridge voltage would be quite near 24VDC. So it is possible to get 24VDC with a different type V/R. Maybe this was in mind of Kohler engineer or someone who manufactured these stators to Kohler.




Tero