What is this electrical component?

London

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Equipment
B1500
Feb 2, 2020
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London
Thanks what do each of these things do? Tractor is dead on a new battery so trying to troubleshoot issues
 

BruceP

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G5200H
Aug 7, 2016
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Richmond, Vermont, USA
Thanks what do each of these things do?
  • The rectifier is really a "diode bridge" containing 4 diodes. Its job is to convert AC to DC. As 'Greensvillejay' says... it NEEDS to be bolted to metal with heatsink compound to keep it cool.
  • The regulator regulates the DC voltage to be around 13..8v
  • The round metal thing may be a RELAY
  • I cannot speak for the other items.

I can tell you that NEITHER the rectifier nor the regulator has ANYTHING to do with the engine starting/running.

Tractor is dead on a new battery so trying to troubleshoot issues
To begin with, you need to focus on the starter-circuit. It is fairly simple to get diesel engine to crank over.

All starter circuits are about the same. (cars, trucks, lawnmowers, tractors...etc) There are BIG wires to carry the current to the starter-motor... and small wires to turn on the the current in the big wires. This is so the keyswitch does not have to carry current.
 
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GreensvilleJay

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BX23-S
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'tractor is dead, with new battery'....
could be bad cables, loose connection, busted safety switch,etc.
really need a wiring diagram to troubleshoot.

the more details you can provide the better we can guess....

'dead', I'm assuming turning the key and starter does NOT spin ??
'dead', NO lights on the dash ??
'dead'....hmm maybe the main fuse blew ??

missing wire on recitfier means old battery wasn't being charged...
 

PoTreeBoy

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Mar 24, 2020
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WestTn/NoMs
Www.kubotabooks.com has an operator's manual that includes the B1500. Toward the end, there's a schematic that's labeled B1400, but I suspect the 1500 is the same.
 
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London

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B1500
Feb 2, 2020
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London
Thanks guys. Have been trying to work through this. I think it might now be the starter motor that is killing the battery on start up. Battery voltage is dropping significantly on trying to start but not turning the starter. If I use a battery with high cca 760 vs the 330 in the original battery it will start. So how do I test the starter motor? Cheers
 

GreensvilleJay

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BX23-S
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OK, silly question
Have you replaced the battery cables with new ones ??
Since a higher capacity battery WILL start the engine, that implies the wiring has enough 'resistance' that a 'smaller' battery won't work.
 
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London

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B1500
Feb 2, 2020
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London
Thanks no but I have tested it with a multimeter and resistance is low. I have taken starter out and tested that and all fine. I have actually come full circle on this and I think the small battery is the issue. shows decent charge but when it trys to turn the starter the voltage drops rapidly and battery then takes ages to recover. going to get a new battery and try that. Cheers all
 
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Henro

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B2910, BX2200, KX41-2V mini Ex.
May 24, 2019
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Thanks no but I have tested it with a multimeter and resistance is low. I have taken starter out and tested that and all fine. I have actually come full circle on this and I think the small battery is the issue. shows decent charge but when it trys to turn the starter the voltage drops rapidly and battery then takes ages to recover. going to get a new battery and try that. Cheers all
Sounds like the original battery is the issue.

The circuit will act the same regardless of battery capacity. It is voltage that pushes the amps through the starter, not the battery ampere rating, as long as the rating is equal to, or better that the OEM battery size.

Getting a replacement battery is likely the solution.
 
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GreensvilleJay

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BX23-S
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'shows decent charge'... that can only be done with a proper 'load test' NOT a voltmeter.
Since the starter works, it's a real good load for the 'load test'.
I suspect the original battery has 1 or 2 'weak/bad' cells and can't supply the current to spin the starter.
 
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BruceP

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G5200H
Aug 7, 2016
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Richmond, Vermont, USA
I have tested it with a multimeter and resistance is low.
NO NO NO!!! testing ohms on a high-current circuit is not the proper way to test. Even a very small resistance can drop large voltage when talking 300Amps.

Instead, use VOLTAGE-DROP tests to detect poor conductors/connections. (measure voltage WHILE CURRENT IS FLOWING)

Example:
  1. clip voltmeter lead on battery minus post (NOT the connector)
  2. Clip other voltmeter lead on engine casting.
  3. Measure voltage WHILE CRANKING ENGINE
If you see more than 50mV (0.050v)... there is a poor connection between the two points.

You can do a similar test for the large battery positive cable to the bendix.

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Thanks guys. Have been trying to work through this. I think it might now be the starter motor that is killing the battery on start up. Battery voltage is dropping significantly on trying to start but not turning the starter. If I use a battery with high cca 760 vs the 330 in the original battery it will start. So how do I test the starter motor? Cheers
You can remove the starter from engine, clamp it (carefully) in bench-vice and momentarily power it with a battery. Expect a large spark (so you are not startled) and the starter should spin freely.

While starter is removed from engine, I usually take it apart, hose down the brushes with contact-cleaner, use compressed air to dry and clean/lube all moving parts.
A small amount of friction on the bushings can suck a LOT of battery power instead of spinning engine.
 
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