520 NOT charging

[Shuboxlover 474]

Hey guys,

Trying to get a 1992 520-H going for a buddy (we'll call this tractor HIS tractor)

I think the only thing I have left to tackle is the charging circuit. All the gauges work and the volt meter reads battery voltage of ~ 12.5VDC

When running, I measure across the alternator and get anywhere from 20-50VAC depending on engine RPM (seemed normal but I still confirmed this with MY 520 and it was right in line)

I measured the between middle terminal of the regulator and ground on HIS tractor and got like 0.950 VDC
I measured the between middle terminal of the regulator and ground on MY tractor and got about 14.7VDC

I thought "sweet, just a bad regulator" NOPE, I swapped mine in just to confirm and it still isn't charging.

I measured between the "body" of the regulator (should be ground) and the negative side of the battery and it's zero ohms (exactly what it should be) so I don't think it's a ground problem.

I am at a loss right now, does anyone have any other suggestions on what to do?

Thanks
Tyson

 

[Bow_Extreme 534]

Did you check the fuse?  

[Ed Kennell 35,833]

Tyson, did you try his reg in your  520 just to be sure his reg is OK ?

[Shuboxlover 474]

Even if the fuse was bad, wouldn't the regulator be putting out ~15-16VDC???

[Ed Kennell 35,833]

Even if the fuse was bad, wouldn't the regulator be putting out ~15-16VDC???

To function properly, the reg needs to be connected to a good battery.     

 

[Bow_Extreme 534]

Even if the fuse was bad, wouldn't the regulator be putting out ~15-16VDC???

Not sure.  I was looking at the wiring diagram last night briefly and need to look again.  

[gwest_ca-(File Mod) 10,503]

There are 2 reasons for the regulator terminal to see battery voltage.

First is the regulator is powered by DC voltage so it needs to be turned on to control the current it passes to the battery.
Second is if the DC terminal does not see battery voltage it means it is not connected to the battery so it can charge it.

Best way to cover all models and wiring systems is to turn the key on but the engine not running. See if you have battery voltage at the DC terminal.

Garry

[Shuboxlover 474]

Thanks for the explanation Garry!!!!

It's FIXED!!!!!

I tested MY 520 for what Garry said, I did in fact have battery voltage at the DC terminal BUT....it was there weather the key was on or off, I don't know if that's a problem or not, hasn't seemed to cause problems yet anyway.

So, after Garry's info, I started more testing on HIS tractor.  I did NOT have battery voltage on the DC terminal not matter the key position.  I put a temporary wire between the battery and the DC terminal, started the engine and VIOLA...14.75VDC!!!!  So, I started ohming that wire backwards starting at the regulator.  I DID have continuity through the 9 pin but continuity stopped on the underside of the fuse block.  The fuse was good, but the connection on the underside was bad.  I think that is what made the PO do some mods to the wiring to begin with and not diagnose it correctly.  Anyway....everything (ALL gauges, lights, charging...everything)  is now working as it should, albeit the wiring is a bit cut up, but at least it's operational.

Thanks everyone for the help!!!!!!!!!!!!!!!!!!

[gwest_ca-(File Mod) 10,503]

I know on some of the 520's there is nothing between the regulator DC terminal and the battery except a fuse so the key does not have to be in the run position.. Sounds like your's is one of them and they may all be like that. Takes a lot of searching of diagrams to know for sure.

Other models often have the regulator DC terminal wired to the ignition switch and activated in the RUN position by connecting it to the battery wire.

Best way to cover all models and wiring systems is to turn the key on but the engine not running. See if you have the required battery voltage at the regulator DC terminal.

Garry

Adding
This applies to flywheel alternator stators only that use a Bendix starter.
It does not apply to the combination starter/generator systems. Edited October 2, 2015 by gwest_ca

[dbadoo 0]

Thank You Garry and Shuboxlover,

   Had the same issue with my '95 520, ran a jumper from B+ on the regulator/rectifier to the + terminal on the battery and it's charging like a champ.   Now I'll go through the path of wires to fix it.

  

[lynnmor 6,796]

Start with the white 9 pin connector near the battery.

[gwest_ca-(File Mod) 10,503]

14 hours ago, dbadoo said:

Thank You Garry and Shuboxlover,

   Had the same issue with my '95 520, ran a jumper from B+ on the regulator/rectifier to the + terminal on the battery and it's charging like a champ.   Now I'll go through the path of wires to fix it.