520H not charging

[Ed Kennell 37,280]

Thanks to you guys, I got my 1988  NEW / FIND  520H running.

 

 I did use it to roll the lawn for two hours, and yesterday put on a clevis hitch and using attachments I got with a Simplicity two wheeler used it to plow and disc my garden.

 

  Using the hydraulics to raise and lower the plow and disc was a lot more fun than operating the spading shovel.  I was using the 1/2 tread turfs without chains, and had plenty of traction. I even pulled out some 2" roots when I got too close to a spruce tree.

 

Now, to the electrical problem.

 

When I got this tractor, It did not start with the switch. The PO had jumped 12v to the solenoid.  All the safety switches were missing.

 

I traced this problem to a bad ignition switch.  I replaced the switch , missing fuses , safety switch jumpers,  and cleaned a lot of terminals.

 

So I got it starting correctly, got the lights working, got the tach , idiot lights and voltmeter working. Could not get the hour meter to work.

 

I noticed the battery was dying when I used the tractor and the voltmeter was showing 8-10v while running.

 

So I checked the RR  B+ to ground  = 3.8vdc @ 2500 .. not good.    RR shows no resistance between any terminals or to ground.

 

Checked the alternator output = 32-33vac @ 2500.   I think this is good..  right?

 

So I need a new RR , right ?    I put that on my to buy list for the SHOW.

 

I do  have several RRs  from Kohler donors. Are these usable ? I could mount It under the hood stand above the battery. 

 

Keep in mind this Is not a restor.,  Just trying to save a good working tractor as cheaply as possible.

 

                    Thoughts ?

 

 

 

 

[gwest_ca-(File Mod) 10,878]

Without the tractor running check the voltage across the battery terminals.

 

Now move the red lead to the B+ terminal on the regulator. Should have the same reading.

 

Now move the black lead to the motor metal or crankcase and you should have the same voltage reading.

 

What this checks is the path the charging current takes to get to the battery.

 

I believe you have a 20 amp charging system on the Onan and most Kohler voltage regulators are 15 amp so good chance you will burn one of them up.

 

Garry

[Theroundhousernr 589]

  All good answers from gary to check into. Guess what Ed. Guess whos new 520H isnt charging correctly either.... Yup mine. I get about 11.95 volts from the RR. I am going to go through all my grounds and make sure the RR is grounded well also. Its wierd, mine works intermitently.

 

   Also , make sure your 30 amp fuse by the starter is good. This fuse is for your charging circuit....

 

  Onan engine specs say approx. 21 volts AC @ 1800 rpm and approx 41 volts AC at 3600 rpms from stator leads . So it sounds like your safe there. The stator resistance should fall right around .06 to .10 Ohms. If all wiring checks out then its safe to look for a RR. I am thinking of trying out the RR's I see on ebay. They are cheap enough to give a whirl and I think they should work fine. Its all solid state componants anyway.

  

    Good Luck. We will get through these little bugs.

  Kyle

[Ed Kennell 37,280]

Thanks Garry and Kyle,   I'll check it out tomorrow.  I did get my spare snow blower  mounted this afternoon and everything  fit up and worked. The lift rod was even the correct length.

 

   My left arm will be thankin that hydro lift next winter. 

[WH nut 553]

Make sure the regulator is wired correctly also and have good connections. Most charging troubles I have seen on onans is dirty connections on the regulator

[stevebo-(Moderator) 8,257]

I think that the voltage regulators on these go often. I just purchased a new one (aftermarket) on ebay for about $22 shipped to my door. Installed it today and she is charging !! Takes all of about 2 mins to change.

[AMC RULES 37,076]

Can you share the item # of that regulator Steve?   

[Ed Kennell 37,280]

Without the tractor running check the voltage across the battery terminals.

 

Now move the red lead to the B+ terminal on the regulator. Should have the same reading.

 

Now move the black lead to the motor metal or crankcase and you should have the same voltage reading.

 

What this checks is the path the charging current takes to get to the battery.

 

I believe you have a 20 amp charging system on the Onan and most Kohler voltage regulators are 15 amp so good chance you will burn one of them up.

 

Gar

 

I removed the tach signal wire for these tests.  Ignition switch  is off.

 

Across the batter =13.2vdc

Red lead to B+      =13.2vdc

Black lead to motor+13.2vdc

 

Alternator to motor  =13.2vdc     Is this confirming the RR is fried ?

+battery to  tach signal wire =12.8vdc The tach does work, but I am surprised to see voltage here.

 

Thoughts ?

Edited April 5, 2014 by ekennell

[Theroundhousernr 589]

Your stator seems to be functioning and you got continuity. I would say it's safe to say you need a new RR according to the onan repair manual. I'm not sure what you mean by alternator to motor... If it's what i think, I'm surprised you don't have a constant drain on the battery.

The tachometer signal wire might read pulses off a ground so you checking what you did is just bridging the circuit. I'm not to sure on that answer though. I'll look into this and confirm.

[ericj 1,578]

ed i know from experience that the volt gauges on these tractors don't always work correct. did you check the voltage on the battery with the engine not running and with the engine running and then running with a load like the light s on. the voltage should go up if everything is working correctly and drop if you have a problem. maybe you have already done this but just didn't state it in your post. good luck and i know somebody that bought an after market rr off ebay and had good luck with it

 

 

 

eric j 

[Ed Kennell 37,280]

Kyle, I removed all 3 wires from the RR.  The alternator still puts out 20-40 vac with 1-3k rpm, so  It's still working. 

 

Found the right and middle(B+) are shorted on the RR.  This explains  how  I see  battery voltage from the alternator terminals on the RR to motor ground. The + battery voltage is supplied to the RR   thru the B+ wire then to the RR alternator terminal thru the shorted  RR.  

  Every thing seems correct except the shorted RR. 

 

Still  don't think I should see 12vdc  at the tach signal wire. May be something shorted in the chopped up idiot light circuit. What is puzzling is the tach still works with the 12vdc on the signal wire.

But I guess the tach does not see the 12vdc because there is no connection to ground.  The tach only sees  the frequency variation in the AC voltage from the alternator.

 

Steve, I found a RR on Ebay for $21 with free delivery.  

Edited April 7, 2014 by ekennell

[Martin 2,131]

Ed, i remember reading on here where the kohler regulator rectifiers have a connection internally between one of the ac terminals and b+. i think the onan rr is the same. i just found this thread and I'm looking for the info on the jumped terminal, but haven't been able to find it yet, usually can get the search engine on here to work in my favor, but not right now. 

 

the tach gets its signal from the AC leg that has the jump if i remember correctly. 

EDIT: TACH SIGNAL IS FROM THE AC LEG THAT DOESNT HAVE THE JUMP. (SEE POSTS BELOW)

 

someone please correct me if I'm wrong here.....

 

searching for the regulator/rectifier autopsy.......

 

soi where are you?

Edited April 9, 2014 by Martin

[Martin 2,131]

found it.......

 

page 18 of 91.....

 

[gwest_ca-(File Mod) 10,878]

+battery to tach signal wire =12.8vdc The tach does work, but I am surprised to see voltage here.

 

The +Bat terminal has 13.2 volts in it from the battery. The tach signal wire is providing a ground for the test meter and the .4 volts is lost to the internal tach components.

 

Does that sound correct?

 

Garry

[Ed Kennell 37,280]

Wow, that's  quite an interesting  post by the "Smokin rodent". 

 

  So the connection I see between the B+ terminal and the right one is normal. BTW, the left one is where the tach signal is connected.

 

  Now I gotta go check some of my old RRs from the Cs.

 

I did just order a new RR from Caltric thru Amazon       Onan 16-24HP 191 1747,2106,2208    $19 and free shipping

Edited April 7, 2014 by ekennell

[Theroundhousernr 589]

I think I'll place an order to. Garry that's exactly what i meant to say you just said it better. Well done.

Sent from my Event using Tapatalk

[Save Old Iron 1,565]

 

soi where are you?

 

 

 

My disguise didn't work - you found me !!

 

I was hanging back  - you guys were doing great with the discovery process.

 

Measuring AC between the two AC terminals on the regulator will tell you the health of the stator. Anything above 32 volts at full throttle will charge a battery

 

 

Two of the terminals are shorted together INTERNALLY inside the regulator. B+ and one of the AC terminals are physically connected inside the reg. It may be important to know which two are connected just for the sake of clarity for future troubleshooting. In the Kohler regs, it's the two terminals stacked on each other.

 

 

 

 

I'm not sure about which two on the Onan style regs. Ed, if you know which two are connected, post it here. Let's say we use an orientation of "lookibg down on the reg, terminals pointing toward the person making the measurement".

 

The image below is what we confirmed as proper wiring of the charge and tach circuits some time ago.

 

 

The question of why DC and AC exist together on the B+ relates to what the tachometer uses as a reference to make its measurement. The Tach will block any DC signal due at its input as it only senses variation in AC voltages, not DC voltage levels. The DC voltage drop you measure thru the tach is most likely from protection diodes inside the tach housing. The clipper circuit acts as a signal limiter for the incoming 30 + AC signal and cuts the 30 VAC signal "off at the knees" when it exceeds 5 volts + or - . The clipped signal is then fed to the circuitry for the RPM measurement. .

 

http://www.allaboutcircuits.com/vol_3/chpt_3/6.html

 

 

The tach uses 12 volts DC for powering the internal circuits and uses the FREQUENCY of the stator AC output as it's "signal" to be measured. Remember , the FREQUENCY of the AC signal, not the VOLTAGE level of the AC.

 

In your particular case, if the tins of the engine are grounded properly and the reg grounded properly to the tins, replace the regulator. They do seem to suffer frequent failures than the Kohler style regs.

[Ed Kennell 37,280]

Aha, I knew the Rodent was watching... Just hanging back, knowing we would learn more if he left us to poke around with our $10 DVMs than if he just gave us all the answers.

 

Thanks again SOI,  The two  that are  connected on my RR are the  center B+ and the Right AC Terminals, using your orientation. 

 

My tach is connected to the Left AC terminal as shown on your pic.  Is it important that the tach be connected to the terminal that is not connected to the B+  to prevent damage to the tach or RR?

I'm thinking the purchasing of these aftermarket RRs may not all be the same and the tach signal could get connected to the wrong terminal.

[Save Old Iron 1,565]

My tach is connected to the Left AC terminal as shown on your pic.  Is it important that the tach be connected to the terminal that is not connected to the B+  to prevent damage to the tach or RR?

I'm thinking the purchasing of these aftermarket RRs may not all be the same and the tach signal could get connected to the wrong terminal.

Ed, the orientation of the two AC leads on the RR only matters when the tractor has a tachometer. Without a tachometer in use, the AC terminals can be interchanged without any issues.

 

The tach wire must be connected to the AC terminal NOT shorted to the B+ terminal, If you do hook the tach signal to the wrong AC terminal, no harm done, Just interchange both AC connections at the RR and the tach will work.

[Ed Kennell 37,280]

       SOI.    Good to know  all us trial and error electrical engineers can't accidently fry a new RR or tach.

[Save Old Iron 1,565]

I just picked up a small Sherline hobby mill machine. Sometime this year, I will be shaving the aluminum casing off one of these Onan style regs to see what's inside. Stay tuned.

[Ed Kennell 37,280]

Autopsy II .... Soon to be released.

[Ed Kennell 37,280]

    Looky what I just found in my mailbox.      Not bad delivery....ordered 3 days ago.  

 

        The center B+ tab is connected internally to the right AC tab.  Same as the original. 

 

 

 

[Ed Kennell 37,280]

Just installed the new RR and lit er up.  Voltmeter shows 14v @2500rpm.  Tach works,  Idiot lights work, headlights work,  and the hour meter even started to work. 

 

I'm calling this a 100% success, and just in time. Now I gotta get the lights working on the boat trailers and get the outboards tuned.....Moving one to Delaware Fri.... the flounder bite is coming.

 

You guys all get an A+    for your support.