Bench Test 580K Instrument Cluster / Gauges

[Johnhrich]

I've bought a used 1990 580K, but apparently the previous owners determined that instruments were simply not needed. Nothing works. I haven't started the process of back tracing the wiring from the instruments to the source yet. Next step. But I did remove the cluster box and start testing it. I replaced the fogged gauge cover by cutting out the fogged area with a Dremel and gluing a piece of clear lucite from Home Depot on the top. Simple and inexpensive. I've tested the continuity of the circuit board in back and confirmed that there's no breaks in the copper strips. Now I'd like to bench test each of the gauges so I know at least that they should work. Volt meter is easy - just test on a car battery. But not sure of the others. Suggestions for testing Tach, hours meter, water temp, oil temp and fuel level? With things available in the above average house garage? I'm remote from the hoe so can't test with it. I can supply power to the gauges from a car batt, but not sure about what the sending units provide to the gauges.
Based on the service manual wiring diagram it appears that the hours meter's simply attached to the key switch, leading me to believe that a continuous 12v supply would run the meter. ?
I'll worry about the warning lights later as well. That would be more a wiring problem anyway.
Thanks for advice.

 

[bowen]

Mine is not a 580K but I can tell you that lots of the lights and circuits work shorting the wire to ground.
You will need a schematic to confirm all this but some of the wires can be shorted to ground to test lights.
Where you have a guage like the oil temp or water temp the sensor usually varies the resistance to ground.
Shorth the wire on like the fuel guage and it goes to the top, etc.

 

[Johnhrich]

Bowen, you're right. I've been doing some additional research and it appears that fuel, water temp and oil temp are all resistance to ground gauges. So I'm going to make a small bench test with a low amp battery with a rheostat to make sure that I don't stress the gauges. Now where I'm stuck is on the tach. It's my understanding from Dale at Tractor Stuff that the Case specification alternator may be different than any standard alternator - so the tach may be different or expect different signal from the alternator. Also still not sure how the hours meter works yet. Any thoughts anyone? thanks,
I've also been able to test all the lamps in the console and now know that they work.

 

[bowen]

My tach & hourmeter is all mechanical from a cable, but yours may be all electrical.
If so I am guessing that the tachometer reads DC voltage from the alternator.
This would need to come from a wire inside the alternator before the voltage regulator.
It could be AC voltage if it come before the diodes, I am not sure.
A generator produces DC and an alternator produces AC if I understand it correctly.
I do think the alternator has something special included to drive a tach or hourmeter/voltmeter.

Are you just looking for the terminal(s) to test and see what they read?

 

[Johnhrich]

Bowen, yes mine is electrical. According to my research there's a special component in the alternator that converts a sine to a square wave to the tach, and the tach measures either frequency or amplitude of the wave, haven't determined which yet. Apparently not voltage like the other gauges. Problem is that I have the gauges at home cleaning and testing, but the hoe is at a remote location. So can't bench test on the hoe alternator (and not sure if I have the correct alternator). I'm trying to see if there's a way to bench test the Tach and hours meter just to see if they work. I have the service manual schematic, so know where the terminals go on the hoe. But that doesn't help on a bench test. Worst case I think that I could probably take the gauge to a diesel shop and see if they can test. But I wanted to do myself if I could figure out.
I did read about your trials with the mechanical drive and probably glad that I don't have one of those.

 

[Emerson]

If yours is anything like mine then your gauge cluster isn't the issue it's the sensors or the wiring to them. When I got mine nothing worked aswell but I've slowly tackled it here and there. So far I have the Battery gauge and Fuel gauge working. next on my list is Oil pressure and water temp.

 

[Vtgreg]

The late 1980- mid 1990s, 580s and 680s hour meter AND tach are pulse driven from the alternators voltage regulator. It is the single tab on the regulator portion of the alternator. This yellow-red wire from the regulator goes through the firewall connector to the back of the tach ( 3 terminal connector) portion of the instrument cluster. You will not find this regulator at napa, advance, etc. you need to go to an older generator/starter repair shop. About $20, if you can find one. If you weld on electric arc weld on these loaders/hoes, disconnect both small wires from the generator-regulator. These instrument clusters get corrosion on the tabs of the mylar backplane, and often don't pass current. Remove the gauges,bulbs and using a pencil eraser clean the contacts.

 

[Johnhrich]

Vtgreg, thanks for the reply. I've been able to bench test all gauges except tach. Will have to wait til I can get it back into the hoe. PM also sent.

 

[Vtgreg]

Johnrich, PM sent.