Oh, RATS ...
my Johnnie won't start!
My JD was starting just so great ... new batteries, compression release ... even in cold weather. One day I started it up & let it run to warm up. After about five minutes, it died ... and, I just didn't start it again that day.
But, that was the last time I could get it started! I tried many times ... Mike & Ben have tried.
My "shop manual" for the 730 arrived; I've printed off stacks of Internet info; Mike & Ben took the starter & generator in to get checked/fixed.
With the wiring diagrams now, hopefully the whole rotten, complicated electrical system can be upgraded. I've been advised to "keep it stock".
That 24 volt 730D of yours is both a positive & negative ground tractor.. That’s a little different than used on most other equipment..
On half of the batteries & one half of the electrical system uses 12 volts negative ground... The other half of the batteries & electrical system uses 12 volts positive ground & the starting & charging system use all the batteries in series for 24 volt starting & charging.. It seems complicated up front but once you understand it, it’s not that bad..
~That 730D essentially uses 3 separate electrical systems [all interrelated but isolated from each other].. That tractor used one 12 volt system to power ½ the lights, fuel gage & accessories, the other 12 volt system to power the other ½ of the lights, accessories & rear lights.. When the starter button was pushed all the batteries were used in series to power the starter & of course the generator needed to charge all the batteries in series at 24 [actually 27-28] volts..
~The 24 volt part of the system is COMPLETELY isolated from the tractor chassis with no part of the 24 volt side touching the metal tractor chassis [starter & generator are isolated from the chassis] .. The 12 volt sides do have return to chassis grounds [one positive & one negative]..
~Your 730D originally came with 4- 6 volt batteries wired in series with 2 batteries providing ½ the 12 volts & the other 2 providing the other 12 volts.. The left 2 batteries supplying the positive ground part & the R/H 2 batteries providing the negative ground part.. There was a small connector wire hooked between the center 2 battery’s connector battery cable & seat box ground..
Most people now just use 2 large 12 volt batteries in place of the original 4-6 volters.. The L/H battery [or batteries if 6 volters are used] hooks the most negative post to the starter’s solenoid post & positive post to the other battery [or batteries ].. The R/H battery [or batteries] hooks the most positive post to the stud on the side of the starter & the negative post to the other battery(s).. You also need a ground wire hooked from chassis [battery box] ground to the cable connecting the two center batteries together..
I know this would go quicker if my mechanics didn't have to work outside in sub-freezing weather...!
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My mechanics are in real life the lumberjacks logging in my woods. See lots of photos from fall into winter on the logging projects. Logging (click here)