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John Deere 70 rectifier/diode

Weekend Freedom Machines » Restoration and Repair Forum » Lawn Tractors and Rear Engine Riders » John Deere 70 rectifier/diode « Previous Next »

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ross dute
Member
Username: Heavydute1
fl
Registered: 12-2011
Post Number: 2
Posted on Tuesday, January 17, 2012 - 5:33 pm:   Edit Post Delete Post View Post/Check IP    Move Post (Moderator/Admin Only)

What is another fix for the stock diode panel.Charging system putting out 25+ AC volts.Can I use 110 rectifier or inline diodes? Anybody done it?
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Roger Henning
Member
Username: Woodpecker41
WI
Registered: 3-2002
Post Number: 6683
Posted on Tuesday, January 17, 2012 - 7:04 pm:   Edit Post Delete Post View Post/Check IP    Move Post (Moderator/Admin Only)

I have been around JD garden tractors since 1975 and I have never seen another way to fix this problem. Having said that what you suggest may work and I have used K series Kohler rectifiers on cast iron Tecumseh engines for years with no problems. Let us know if it works or not. Roger
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ross dute
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Username: Heavydute1
fl
Registered: 12-2011
Post Number: 3
Posted on Wednesday, January 18, 2012 - 1:09 pm:   Edit Post Delete Post View Post/Check IP    Move Post (Moderator/Admin Only)

Thanks Roger.....Do you have wiring diagram 68 SF and up so I can compare the kohler diagram? Thanks. Ross
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Roger Henning
Member
Username: Woodpecker41
WI
Registered: 3-2002
Post Number: 6686
Posted on Wednesday, January 18, 2012 - 5:04 pm:   Edit Post Delete Post View Post/Check IP    Move Post (Moderator/Admin Only)

The Kohler wiring is completely different than a VH70s. The Kohler has two AC leads coming off the stator (as do the cast iron series Tecumsehs) that are designed to produce 28+ volts and either 10 or 15 amps at wide open throttle and go to the outside two spade lugs on the voltage regulator (there are 3 spade lugs). The middle spade lug on the regulator has the DC voltage produced that goes to the battery through the ignition switch. The VH70 system is much smaller amp output so I do not think it would work with a Kohler 10 or 15 amp regulator. I think that is why it hasn't been done before. For wiring diagrams of JD engines try placing a wanted ad in the Wanted Section. Roger
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Bob Tiarks
Member
Username: Bltee
WI
Registered: 4-2007
Post Number: 113
Posted on Friday, January 20, 2012 - 8:43 pm:   Edit Post Delete Post View Post/Check IP    Move Post (Moderator/Admin Only)

Half wave rectifier such as these http://www.radioshack.com/product/index.jsp?productId=2062591 will cut voltage in half . Wiring it up might take a little imagination. One side and and one diode will give you 1-1/2 amp charge rate. Two in parallel will give 3 amp charge rate both at 12.5 plus DC WOT
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Steve Sunderman
Member
Username: Wyogreen
WY
Registered: 8-2009
Post Number: 392
Posted on Saturday, January 21, 2012 - 10:00 am:   Edit Post Delete Post View Post/Check IP    Move Post (Moderator/Admin Only)

Building a full wave bridge rectifier is really not all that hard. 4 diodes of the proper amperage rating will take care of that. The real problem is regulating the output voltage to keep from overcharging the battery. If you think about it, almost any regulator of the proper amperage rating should work. You're just taking AC voltage, rectifying it to DC thru a full wave bridge rectifier, and regulating the resulting DC voltage to something like 13.5 volts. I have no idea what the JD 70 puts out for voltage or amperage. If it puts out the same AC voltage and amperage as say the JD 110, then a 110 voltage regulator should work, as long as it is wired up the same.
Steve
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Bob Tiarks
Member
Username: Bltee
WI
Registered: 4-2007
Post Number: 114
Posted on Saturday, January 21, 2012 - 3:33 pm:   Edit Post Delete Post View Post/Check IP    Move Post (Moderator/Admin Only)

It is a 12V 3A rectifier panel arrangement as explained on page 51 of the attached manual.

http://toprake.com/index.php?module=documents&JAS_DocumentManager_op=downloadFile&JAS_File_id=2
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Steve Sunderman
Member
Username: Wyogreen
WY
Registered: 8-2009
Post Number: 394
Posted on Saturday, January 21, 2012 - 6:37 pm:   Edit Post Delete Post View Post/Check IP    Move Post (Moderator/Admin Only)

After reading the manual Bob posted, it should be an easy matter to obtain a couple of diodes and replace the ones on the diode panel. Since there is no voltage regulation on this circuit, you only need a couple of diodes rated to handle at least 35 volts at 3 amps.
Good luck, Steve

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