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JD LT155 SN072651 wiring problem


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04-17-07, 05:01 PM   #1  
JD LT155 SN072651 wiring problem

ding mower w/o elec PTO and electronic control board, has four Bosch type relays in control circuits. The only wiring info I can find is on the JD site which shows wiring harness only. Need wiring or schematic diagram to trouble shoot starting problem. Found one in line diode that did not read good and jumped out , problem solved. Almost!!!Got a new diode from JD store and put in line, same problem. Put jumper in again, all works well. With a schematic, I could determine if the diode was an essential devise and if not could be jumped out. Oh for the lack of a diagram. Tom

 
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04-17-07, 08:55 PM   #2  
I don't know where to find a diagram, especially for a PC board like that. I would suspect that there wouldn't be a diode there if it wasn't needed. It just blew the new diode? Did you install one with the proper amperage rating? Even if it wasn't essential to have a diode there, the fact that it's burning up is indicative of another problem. Patching it with a jumper would just be a bandaid, not a repair of the actual problem.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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04-18-07, 12:28 PM   #3  
It was never my intention to leave the jumper in place of the diode, that was placed there only to test the starting circuit. You are right, the diode is there for some blocking purpose. The diode is not bad, and is a Deere part as well as the new one tried in its place. This mower is probably an HD or Lowes sold unit and does not have the PC board, but does have four Bosch relays.
We have solved some of the problem, but could still use a schematic to check out and service the rest of the circuitry. I really appreciate your reply and still hope that you can come up with a schematic source.
This particular mower was left at another repair shop for one year, according to the owner, and finally returned to him with, I'm sorry we just can't fix it.
Always good to hear from "Cheese" God Bless Tom

 
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04-19-07, 10:36 PM   #4  
It was at a repair shop for a year and returned un-repaired!!?? Sheesh. What exactly is it doing? Have you verified that all the relays are working properly? Not just clicking, but making proper contacts when on and off? I believe these relays close some connections and open others when on, and close some and open others when off as well.

Seems like moisture likes to get in those relay housings and corrode the contact points. Especially on mowers that people wash often, or that stay outside.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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