John deere 70 excavator

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timmtnman
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John deere 70 excavator

Post by timmtnman » Fri Jun 16, 2017 5:49 pm

I just purchased a JD 70 1986 and it has starting issues. Sometime s it starts good and then you have to click the switch a few times and it will start and sometime it won't start at all. When I put a battery charger on it it will start. Has two batteries wired up for twelve volts but it is supposed to be a 24 volt system. Does anybody have a wiring diagram or advice to fix the issue. Thanks in advance for your help.

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gregjo1948
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Re: John deere 70 excavator

Post by gregjo1948 » Sat Jun 17, 2017 4:11 am

If you're sure about it being a 24 volt system, I believe, you connect 12 volt batteries positive post to negative post. That should give you 24 volts. If you connect pos. to pos,, it'll give you 12 volts.
JD 350B diesel 6way blade, Case 580B Loader/backhoe, Farmall 504 high crop w/ flail boom mower, International 404 , International 284 diesel w/belly mower, 1972 Ford F600 dump truck, Galion 3-5 roller, Allis Chalmers D17, 1620 Ford

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Stan Disbrow
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Re: John deere 70 excavator

Post by Stan Disbrow » Sat Jun 17, 2017 7:09 am

Hi,

Deere has used two types of 24v systems over the years. I am unfamiliar with your particular machine, so I will keep this fairly generic.

1) Some 24v designs use contactor relays to series the batteries to the starter for 24v, then switch them back to parallel for 12v charging, lights, radios and whatnot.

2) Some 24v designs are 24v always, so no contactor relays.

3) Some people have issues with the contactor relays and change everything over to 12v, but still use a second battery in series just for the starter. In this case, the battery with the negative terminal to the frame is charged by the alternator. The other one needs periodic time on a charger.

4) Some people change everything to 12v, including the starter. Which, then needs two really good batteries in parallel to get enough power to the 12v starter to turn over an engine that really needs 24v power.

I think you are looking at either number 3 or 4 from what you describe. Only in the case of Number One will you see fat relays in the machine.

You do have to know what you have installed for sure. Sticking 24v worth of battery onto 12v anything leads to letting lots of smoke out.....

Stan
There's No Such Thing As A Cheap Crawler!

Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

timmtnman
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Re: John deere 70 excavator

Post by timmtnman » Sat Jun 17, 2017 6:37 pm

Thanks for the great info. The guy I bought it from put two batteries in it, had the starter rebuilt, and a new solinoid. The batteries where wired together for 12v and don't know what volt the solenoid was he got was, no markings on it. So I put a 24v solenoid on and wired the batteries for 24 volts and it starts every time now with no problems. The instrument gauges all had 24v bulbs in it and that lead me hook it back up to 24v. Is there anything I should watch out for or check to make sure it is right. I have not found or seen any contractors yet. Thanks for your help

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Stan Disbrow
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Re: John deere 70 excavator

Post by Stan Disbrow » Sun Jun 18, 2017 6:39 am

Hi,

If you had anything 12v on there, like the alternator or regulator, they would have smoked when you first started it up. The fact that the bulbs are 24v tells me this is a full-time 24v system. So, no pesky contactor relays. If they were there, you would have found them. They are big, and the fat battery cables lead right to them. ;)

So, all that happened is the new batteries wound up paralleled when they ought to have been seriesed. Well, there are a lot more diesel things out there with 12v in parallel then there are 24v in series, so it is easy to see how that might happen.

Good that it is going again. :)

Stan
There's No Such Thing As A Cheap Crawler!

Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

timmtnman
440 crawler
440 crawler
Posts: 165
Joined: Sun May 15, 2016 3:44 pm
Location: Sylva NC

Re: John deere 70 excavator

Post by timmtnman » Sun Jun 18, 2017 10:02 am

Well everything works except I have the battery charge light on the instrument panel. How do you go about checking the alt and how should the wiring be from starter to alt. Looks like they made a jumper wire from alt to starter. Don't know if that should be there or not.

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gregjo1948
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Re: John deere 70 excavator

Post by gregjo1948 » Mon Jun 19, 2017 4:24 am

When ignition is on, there should be a hot wire going to the alternator. Usually it is larger than the other wires attached to it. Depending on what you have, the regulator may be within the alternator. What make and how many wires attached to the alternator?
JD 350B diesel 6way blade, Case 580B Loader/backhoe, Farmall 504 high crop w/ flail boom mower, International 404 , International 284 diesel w/belly mower, 1972 Ford F600 dump truck, Galion 3-5 roller, Allis Chalmers D17, 1620 Ford

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Stan Disbrow
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Re: John deere 70 excavator

Post by Stan Disbrow » Mon Jun 19, 2017 6:11 am

Hi,

The power run is from the battery to the ign switch. A line runs from the switch to the regulator to turn on the cut-out. Inside the regulator, the cut-out feeds the regulator itself. Which, in turn, has a line running to the field coil of the alternator. Once energized, the field coil makes a magnetic field and that, as it rotates, produces power in the armature. That is 3-phase AC, which runs through sets of diodes inside the alternator to convert it into DC. Then, there is a larger line running back to the battery.

The dash light is usually driven from the regulator and tells you it isn't seeing a voltage rise from the alternator. With it lit, I presume that the regulator is getting power from the ign switch. But, you will have to use a voltmeter and see if the field coil has power at the terminal. You can also use the voltmeter right on the battery terminals for a quick check. If the alternator is not working, you will see 24-25 volts. If it is working, you will see 28-30 volts.

What I hope here is that someone didn't half-convert a 24 volt system to 12 volts by replacing the alternator and regulator only and just rewire the two batteries and leave in the 24 volt starter. Because, if they did, now the alternator and regulator will be junk.....

Stan
There's No Such Thing As A Cheap Crawler!

Useta Have: '58 JD 420c 5-roller w/62 inside blade
Useta Have: '78 JD350C w/6310 outside blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

timmtnman
440 crawler
440 crawler
Posts: 165
Joined: Sun May 15, 2016 3:44 pm
Location: Sylva NC

Re: John deere 70 excavator

Post by timmtnman » Mon Jun 19, 2017 5:26 pm

Thanks go the help. Took the alt off today and had it checked out. Checked good and is a 24v alt. It has a larger white wire hooked on the bat terminal and a white jumper that I replaced to the 2 wire plug in and the other I hooked up to a green white stripe wire which I assume goes back to the gauge light. Not really sure about that. Have not seen a regulator yet, but have not looked for one. So after cranking red light is still on and the alt puts out 15v and the green white stripe wire puts out 1.4v.thinking that is the problem somewhere. It is a Remy alt. What does the regulator look like and where are they usually located at.

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gregjo1948
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Re: John deere 70 excavator

Post by gregjo1948 » Tue Jun 20, 2017 3:58 am

If it's a Delco-Remy, I think the regulator is probably inside the alternator. I think, one of the smaller wires, has to go the the ignition switch to a hot pole when ignition is on. That hot wire is needed to excite the alternator and start charging.
JD 350B diesel 6way blade, Case 580B Loader/backhoe, Farmall 504 high crop w/ flail boom mower, International 404 , International 284 diesel w/belly mower, 1972 Ford F600 dump truck, Galion 3-5 roller, Allis Chalmers D17, 1620 Ford

timmtnman
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440 crawler
Posts: 165
Joined: Sun May 15, 2016 3:44 pm
Location: Sylva NC

Re: John deere 70 excavator

Post by timmtnman » Tue Jun 20, 2017 5:20 pm

I believe I found the regulator. Has New Era on it with 3 terminals H B S has 24volts on B and S all the time with switch on or off. Don't get any reading on H. Think I have a bad regulator now.

timmtnman
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Posts: 165
Joined: Sun May 15, 2016 3:44 pm
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Re: John deere 70 excavator

Post by timmtnman » Fri Jun 23, 2017 4:18 am

Talked with deere and the part I found was the horn relay. Said that there was a relay that excites the alt located in the console. Hopefully that will fix the problem. Wanted to give an update on this project.

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