ucsbuilders
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Move if necessary, this seemed the most appropriate location.
Long time lurker, first time poster. I recently picked up a 1997 JLG N35E man boom lift from auction. I was able to find the original owners to hear why they were liquidating it. The machine died in use and had no functions working. I was told they had spent over 2 hours on the phone diagnosing w/ JLG and the conclusion was it needed a DC motor controller and they had been quoted an absurd price to repair.
One day I'll learn to never trust someone else's diagnosis. I'm not dumb, but this isn't my area of expertise. I bought a new motor controller to throw in and same issue, nothing rectified. OK, time to KISS. I started poking around w/ a multimeter. First, the unit came w/ no batteries so I've got a set of new batteries in and and voltage is good. I've been able to find wiring diagrams online and noticed that it seems some things were rewired in the process of doing diagnostic prior to me receiving it.
Had a hunch there was a problem with the key switch which was correct. I replaced this 12 dollar part and now some things have started happening. Most notably if I step on the foot pedal in the basket, the machine beeps at me. Hooray! If I attempt to steer, I can hear both steer contactors engage.
I should add at this point, I had a heavy equipment tech come out the other day to look at it. He proceeded think the main contactor was bad and also possibly the pump motor as jumping power to it didn't kick it on. Well I pulled the main contactor out and bench tested it. It checks out. It's fine. I pulled the pump motor and it also checked out and then realized that negative power to it is also contactor controlled so when we fed it 48v positive, there was no negative to complete the path. Moral of that story, I just need to put in the effort myself.
So further investigation I have determined that I have no power at the 7v fuse on either side regardless of key position. I'm starting to lean towards the tach board being damaged. There is power at the 20v fuse on both sides. The 7a fuse is good, but it simply isn't getting power.
There is no power going to the DC motor controller. The green led does not light up at all. The main contactor is not being engaged which I suspect is the culprit of that and I was getting thrown off because I was seeing continuity to negative 48v on the positive 48v side. I'm pretty sure the original motor controller is fine (though some asshole damaged it when removing the potting to inspect it by using a drill bit that deleted some traces off the primary pcb which he "might" be able to repair if someone has a picture of the backside of that board).
So where do I go from here? Where is 7v power supposed to come from for the fuse? I'm assuming the tach board is supposed to supply that and that more than likely I have a bad board there that has caused all these issues.
Any help is most assuredly appreciated to help me get this thing going so I can finish building my house. Thanks!
If anyone has some actual pictures of the wiring in the motor compartment, that would also be handy.
FWIW the serial number ends 29739.
Long time lurker, first time poster. I recently picked up a 1997 JLG N35E man boom lift from auction. I was able to find the original owners to hear why they were liquidating it. The machine died in use and had no functions working. I was told they had spent over 2 hours on the phone diagnosing w/ JLG and the conclusion was it needed a DC motor controller and they had been quoted an absurd price to repair.
One day I'll learn to never trust someone else's diagnosis. I'm not dumb, but this isn't my area of expertise. I bought a new motor controller to throw in and same issue, nothing rectified. OK, time to KISS. I started poking around w/ a multimeter. First, the unit came w/ no batteries so I've got a set of new batteries in and and voltage is good. I've been able to find wiring diagrams online and noticed that it seems some things were rewired in the process of doing diagnostic prior to me receiving it.
Had a hunch there was a problem with the key switch which was correct. I replaced this 12 dollar part and now some things have started happening. Most notably if I step on the foot pedal in the basket, the machine beeps at me. Hooray! If I attempt to steer, I can hear both steer contactors engage.
I should add at this point, I had a heavy equipment tech come out the other day to look at it. He proceeded think the main contactor was bad and also possibly the pump motor as jumping power to it didn't kick it on. Well I pulled the main contactor out and bench tested it. It checks out. It's fine. I pulled the pump motor and it also checked out and then realized that negative power to it is also contactor controlled so when we fed it 48v positive, there was no negative to complete the path. Moral of that story, I just need to put in the effort myself.
So further investigation I have determined that I have no power at the 7v fuse on either side regardless of key position. I'm starting to lean towards the tach board being damaged. There is power at the 20v fuse on both sides. The 7a fuse is good, but it simply isn't getting power.
There is no power going to the DC motor controller. The green led does not light up at all. The main contactor is not being engaged which I suspect is the culprit of that and I was getting thrown off because I was seeing continuity to negative 48v on the positive 48v side. I'm pretty sure the original motor controller is fine (though some asshole damaged it when removing the potting to inspect it by using a drill bit that deleted some traces off the primary pcb which he "might" be able to repair if someone has a picture of the backside of that board).
So where do I go from here? Where is 7v power supposed to come from for the fuse? I'm assuming the tach board is supposed to supply that and that more than likely I have a bad board there that has caused all these issues.
Any help is most assuredly appreciated to help me get this thing going so I can finish building my house. Thanks!
If anyone has some actual pictures of the wiring in the motor compartment, that would also be handy.
FWIW the serial number ends 29739.
