Hello!
We've had this machine for a while. It finally stopped moving.
I'm not sure if this is relevant BUT In the past, we've had problems with the high speed engaging, especially under load and especially in reverse with a load. We learned to deal with it because none of the forklift 'experts' in our area could figure out the issue.
So, here is what I've done:
I removed the side panel and the top panel to access the controller, contactors, and control wiring/switches.
I found the FWD/REV contactors pull in just fine. I'm not too sure which contactor is the 1A but I am willing to bet that the control of that contactor has something to do with this... but I've learned to not jump to conclusions.
I have a schematic of the EV-1 (oh, yeah, the controller I have is the EV-1) but not everything is clearly defined. I am going to assume that the "TRACTION ARM" motor is the one that drives the truck forward and backward. It looks like the FWD & REV contactors are interlocked in several ways (yay redundancy!). So, the positive feed for the motor goes through A1 contactor, then either the F or R contactor depending on the selection at the stick, and then to the motor. The negative side of the motor goes to a sensor which isn't telling me much but it looks like a shunt in the schematics (no clue where this is on the truck), then it connects to Batt neg.
So, to me, if the F & R contactors can engage and if I can assume just for a minute that the inline "sensor" on the negative side of the motor is okay, the only other thing to get in the way of engaging the motor is the 1A contactor.
1A appears to be quite the security guard in this machine. Load, overheating, acceleration... everything can cause this thing not to engage... but I'm not sure where to begin. I see there are a few experts on here and I am hoping you are still around to give me a hand.
Thanks in advance! I can't wait to poke at this more!
Showing items 31 - 41 of 41 results.
I think I'm picking up what you are putting down. Your info is great and I appreciate it!
So, I found the thermal protector, jumped it out, but still could not move. FWD & REV contactors still closed but not the 1A contactor.
The 1-AD is a driver for the 1A to send a negative to the coil for 1-A contractor
All of the contractors will have a constant positive ( battery volts ) the card sends a negative to close them the thermal protector
If it is an ev-1 will be mounted on scr 1 it will have two wires that go to card you can jump the two wires and see if it moves make sure it is the thermal protector though there are two types of thermal protectors one will screw into scr 1 and one will have a screw that holds it on the scr 1 look up thermal protector on ev 1 on google it should show a picture of it
Your card has two sides right and left. As you request certain
Functions the input will go into card and the card will send a negative to selected component there is also ,which you will see on diagram , a pmt driver , that is a safety driver
Pulse monitor trip if there is stuck contact etc card will not allow unit to move or. Contacts to close
Again make sure you have the thermal protector it is on the unit to prevent it from moving in case the motor or scr unit gets too hot it will allow the contacts to close but will not allow scr control to turn on which in turn causes motor rotation
@DyslexicNerd_01
The serial number: 1A111973
Okay, those switches have power AND the FWD/REV contactors pull in when the stick is pressed forward/reverse with the brake switch closed. Everything there seems to be okay.
@John_Bradley
I'm sorry, I don't have a lot of info on this machine and can't see much in regards to wire numbers. I'm more than happy to check some values but some wires are labeled and some are not. It's tough to trace wires and every time I do, it's a 50:50 chance they match with the EV-1 diagram... or I'm just not doing it right. Bare with me. :)
I do see wire 29 on the EV-1 diagram. From Batt negative to R5, I get 4.8V with the 'key' (just a toggle switch) on. Adjusting the Accelerator (I assume that's the joystick to go forward or backward) does not change that voltage.
Documentation is sparse for this machine. I couldn't tell you what #1 REC is but I know it exists just through general info on the EV-1. Clearly, my forklift isn't wired quite as the EV-1 general schematic is. I have no clue where the shunt or thermal protector would be. It sounds like you know your stuff and it's great that you gave some good indicators with wire colors but without a schematic for this particular truck, I'm a bit lost. I'd love to try what you have mentioned.
On that note, I see something on the EV-1 diagram between the controller card output an the coil of 1A marked "1AD." I'm not sure what it is but could that be something to look at?
First thing , check voltage wire 29 on circuit board that is your potentiometer wire it should be around 3. 5 volts as you push accelerator it will will drop to less than 1 volt if it doesn't drop below 1 volt 1 a or bypass will not engage
2- check voltage at T-2 that will tell you if you have a bad #1 rec also test the shunt if it has dark marking it could be faulty with your symptoms I would also suggest to test drive motor also look at the thermal protector it will have two wires a black and gray I also had issues with plug on card unplug z plug look at pins make sure they are all in tightly and plug back in and put a piece of cardboard between lock and plastic base that keeps plug tight in card if forward and reverse come in then it isn't switches or safety switches ie brake etc it is a control issue the symptoms you describe is more common with rectifier, shunt , control card , motor , thermal protector or fuse
Correct the forward and reverse contactors should not click if the switches do not have power. They still will have one side connected as that is the default position. What's the serial number for this lift. I can get a more accurate wiring diagram with that.
Basically the brake switch needs to be closed for the presence switch to get power, and the directional switches need the presence switch to be closed for them to get power. Basically they are wired one after another.
No need to pay whatsoever happy to help!
Thanks again for the reply.
Correct me if I am wrong but if the directional switches didn't have power, then the FWD & REV contractors wouldn't pull in, no?
I am reading TB2 is the set of wires on the bottom of the SCR card but I am not seeing TB1. Could you please tell me where TB1 is?
I'm not quite sure what you mean by "it requires the switch in front of the switch to be closed"
Thank you again. If you can help me get thing thing going, I'd love to toss some reward cash your way.
Say, do you happen to have a schematic for this particular machine?
I would recommend checking the voltage at the directional switches in the handle. When the lift is on and you are standing on both pedals you should see battery voltage. If you don't, check the presence pedal switch. If you don't have voltage there check the brake switch for voltage.
The way these older lifts are wired is it requires the switch in front of the switch to be closed, then it take the input from the handle to close the A1 contactor.
With the A1 contactor operating off battery voltage, it will most likely be an issue within that circuit.
TB1-3 on the control card sends voltage through the circuit. Then L9 is the reverse input and L10 is the forward input on the SCR card.
Okay, Here's what I've found.
I removed all 4 large fuses and tested them, not knowing which one is Fuse 1 (my schematic isn't great), just to be sure. They all seem to be within spec of 0.3ohms or less, even when jiggling them around.
I put my voltmeter on A1 coil wires. I'm not too sure when it should be live but at no point did it have battery voltage (or any as far as I can tell) BUT I did put the coil wires 'direct' to the battery (fused, just in case) and the contactor closed just fine.
Say, when is A1 suppose to be energized? (EDIT: Sorry, I just saw that it should be when activating travel. I did that but no voltage at the coil for A1).
So, the problem seems to be in the control wiring or the switching side of the controller.
I wish I had a proper schematic for this thing. For the A1, I show 41 on the negative side but 42 on the positive side but the controller schematic I have shows it to be 10.
Do you have any other suggestions? I only have an hour or two per day to tackle this thing and it's not the easiest to work on but I'll keep at it as long as you are willing to help. :)
Thanks so far!
No worries, even if you reply you still can only see the original post for some reason.
When testing fuse 1, removed it fully, this is where the A1 contactor gets power before going to battery positive. Make sure to unplug the battery first. It is held in by a bolt/nut on each side. Take your meter and test on one end of the fuse and the other. When testing i also recommend to wiggle the fuse a bit to see if it is slowly dying. A good fuse will test at 0.1ohms but it's acceptable at 0.2 or 0.3 ohms.
If this fuse tests good. I would test the control wires for the A1 contactor. You should see battery voltage when activating travel. If you see the right voltage there I'd replace the whole contactor.
THanks for the reply! I'm not sure how to reply to your post specifically. Mine shows up when I click reply but here are some answers to your questions.
1. When attempting to travel do any of the contactors try and close?
Yes. FWD or REV closes if I select one or the other.
2. How do the tips of the A1 contactor look? There shouldn't be lots of black marks or pitting.
Fine. I mean, normal for it's age but A1 is not pulling in at all.
3. When stepping on the brake pedal does the brake on the motor fully release?
It seems so. There is a limit switch on there that does engage/disengage and it electrically works fine. I can't manhandle-wise force the brake one way or the other.
4. Do the hydraulic functions still work?
All the fork movements work fine.
5. If you remove Fuse 1 how does it test? It should be no higher than 0.3hms.
I'll have to check that but 0.3ohms from where to where?
Hello, a few questions:
1. When attempting to travel do any of the contactors try and close?
2. How do the tips of the A1 contactor look? There shouldn't be lots of black marks or pitting.
3. When stepping on the brake pedal does the brake on the motor fully release?
4. Do the hydraulic functions still work?
5. If you remove Fuse 1 how does it test? It should be no higher than 0.3hms.
With these older machines the travel functions in the handle are on the same circuit as the brake and presence pedal switches. If one of these switches does not close, then the controller will never get an input. I've seen it happen where there isn't enough brake pressure in the lines so the brake never opens even when the operator is on the pedal.
Typically if a contactor is bad it will either become welded closed or close and immediately open back up. If it is either of these, the contactor tips need to be replaced.
Hopefully this helps you down the right path!
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