Jlg 40ha ??

[willie59]

Did you determine which relay the blue wire of the amplifier board goes to? I'm still curious about that.

 

[harveje]

Happy Easter
It Powers a relay for the drive buzzer, I c why it was unhooked.
What does the pots on the board control?

 

[willie59]

It Powers a relay for the drive buzzer

Ok, that sort of makes sense, but I don't know why they did it that way. From what you're describing that amplifier board is (was) used to power a motion alarm when the machine is being moved. Just a guess, maybe an option that the original purchaser requested on the machine when JLG built it. I don't know why they did it with that board, it could have easily been done by using the brake circuit. But hey, I don't build this stuff. In your case, since it appears to have been used to power up a motion alarm, you could simply remove it and have no consequence.

But for the sake of curiosity, that's a PWM input to 12V output board. Basically, here's what it was doing on your machine. When you work the drive controller, fwd/rev, the controller sends a Pulse Width Modulation signal to the control valve via brn/blu and brn/red wires. They tapped into that circuit and sent those wires to that amplifier board. The amplifier board takes that PWM input signal and converts it to a 12V output signal to work a motion alarm and also not allow any interaction between brn/blu and brn/red wires. In your case, simply remove it. Which is good, because if that board were causing your problem and you needed to replace it, oh, somewhere in the 5 to $600 range. Yep.

 

[harveje]

The ground on the alarm has been un hooked for a long time it looks like, I just jumped it to a good ground. Boy that's allot of technology just to drive a horn. But why the pots? audible / tone adjustment?
I did find out that if the platform drive speed switch is in low both fwd and rev work rather smoothly, switch in hi one direction jerks and buck

 

[willie59]

I haven't had to adjust one of those amplifier boards before, not familiar with the procedure. But in your case, if it were me, you don't need that board, sell that sucker on Ebay for 2 to $300 bucks! That's the JLG part number on the top right corner of the board in the pic. It's typically used on the 100/110HX and the 120HX for the boom down lock out circuit on those machines.

I'm kind of stumped on your drive, if in fact it works smooth in both directions in low range, but bucks in one direction only in high range. :beatsme

 

[harveje]

Well I’m back working on the jlg. Had pump / drive issues. Work pump was getting very hot and hyd pressure would drop. Found that someone had the dump valve relay jumped causing the valve to always be energized. Now I’m having idle, low, high rpm issues. Sometimes it works ok. Other times idle 7-800 rpm and that’s it no matter what. ?? What is a adlow relay and it’s function?? Google gave me the finger when searching. And what triggers the e301 governor ?
The intermediate crap drives me crazy.
Thanks

 

[OFF]

And what triggers the e301 governor ?
Thanks

There is a module controlling the governor mounted to the back or counterweight side of the ground control panel. Very well hidden.

 

[harveje]

I'll go on the hunt.. I'm having a heck of a time with idle, mid and high rpm. sometimes everything works ok, then it does to heck.. On the back of the panel, there the starter relay and a adlow relay that I think is a starter lockout relay. I've not followed all the wires for the 301 but there's (can't remember the exact order ) (+,-, sig, sig, gov,gov, high speed). the signal comes from the ESC, and the gov wires go to the actuator, h.s. goes to the high engine relay- What is normal engine rpm's for this unit in ground and platform position? Thanks,