Yet another Lincoln Ranger 8 with auto idle problems

[abe79]

Hi everyone,

I recently bought a used (and abused) Lincoln Ranger 8 with Kohler engine. The face plate was gone, panels dinged up, hour meter broken, and sticker on the Kohler engine with model number torn off. Despite all of this, it ran like a top and was cheap so I bought it. I brought it home to really give it a test run and discovered that it wouldn't idle up when I strike an arc or when I run any power tools from the outlets when in auto idle mode. When I flip the switch to high idle mode it idles up and works perfect...it welds great and powers any tool I plug into it at full power. I figured the problem was in the idler pc board and specifically that the current sensor was probably malfunctioning. I went online and found the current sensor and replaced it and tried it again...nothing. It still wouldn't rev up when I tried running a grinder or striking an arc. So then I took the board back to the lab, found the service manual with the schematic and went to work.

Right off the bat I noticed capacitor C27 was leaking a white powdery substance so I replaced it and I replaced C2 while I was at it as well. I figured the problem had to be in the top section of that schematic, from X2 (current sensor) following the path all the way to number 3 on the connector since that's where 215 wire connects to that leads to the idle solenoid. I tested all the diodes in this section and found DZ8 to be faulty. I replaced it with a new diode and decided to put the board back on the welder and test it again. When I turned on the welder I noticed it revved up a few times then idled down so I thought I was golden. I tried welding and as soon as I started an arc it revved up immediately...but then it idled back down in less than like 2 seconds and then up again and did this like 5 times before it went back to normal idle. It did the same thing when running an angle grinder on it. Took the board back to the lab and decided to just replace all polarized caps (except C22), all diodes in that top section, the mosfet Q4, and even the IC's X1 and X4. After I replaced all these things I put the board back and tried the welder again...same thing. When I strike an arc or use a power tool off the outlets it will rev up and down repeatedly like 5 times then idle back down. Flipping switch to high idle still works like it should.

At this point I have no idea what the problem could be, but I'm determined to fix it. That's why I've come here for help, as I know there are a lot of super knowledgeable folks on here when it comes to these machines. There's no way I'm caving in and buying the board online which even used ones cost more than what I paid for the machine.

Oh and before anyone asks, yes I've gone through the machine checked for bad connections and cleaned contacts and even replaced the welding lugs/terminals.

[12345678910]

How did you get the schematic and drawing ?

[duaneb55]

One thought that comes to mind is the idler solenoid/linkage adjustment. May not be retracting (plunger not bottoming out) completely. ???

[duaneb55]

How did you get the schematic and drawing ?

It's in the Service Manual.

[abe79]

How did you get the schematic and drawing ?

Schematic and drawing are in the Lincoln service manual SVM107-B. I can send it to you if you need it.

[abe79]

One thought that comes to mind is the idler solenoid/linkage adjustment. May not be retracting (plunger not bottoming out) completely. ???

I thought about the idler solenoid, but it retracts fine when I flip the switch to high idle?

[duaneb55]

I thought about the idler solenoid, but it retracts fine when I flip the switch to high idle?

The idler solenoid de-energizes and extends for high idle. Make sure the plunger bottoms out in the solenoid bore at low idle when energized by the PC board.

[abe79]

Here's video of what it does when I run an angle grinder. It also does this when you first start the machine:

https://youtube.com/shorts/vkChkEA4wrA?feature=share


And here is showing the solenoid when switching to high idle manually:

https://youtube.com/shorts/BZQacEs_L4g?feature=share

[abe79]

I just noticed something after watching these videos that I didn't see before...it looks like the little bracket connected to the plunger is hitting the back panel (since I have the top panel off that back panel leans forward). Could this possibly be shorting the idler solenoid to ground causing it to keep energizing and de-energizing like that when in auto idle?

[abe79]

Well I just busted that theory...went out and tried again this time putting the top back on so the back panel stays back where it should be and it still does the same thing even with the bracket not touching that metal panel.

[duaneb55]

Thinking out loud, try a greater load on the AC output.

[duaneb55]

Does the current transformer on the board have the required 3 turns thru the coil?

[abe79]

Thinking out loud, try a greater load on the AC output.

I'll try that.

Does the current transformer on the board have the required 3 turns thru the coil?

Yes sir (currently have the board off the machine).

[abe79]

Update: I tried a greater load on the AC output and still does the same thing. It does the same when trying to strike an arc. I ordered a new idler solenoid to see if that helps any. Once it arrives I'll install it and see what happens.

[duaneb55]

Have you checked to see if 12VDC drops out at the solenoid terminals? If it doesn't, then the solenoid coil would be suspect. If power drops out then the idler board is still suspect.

[abe79]

So there should be 12v at the solenoid terminals when its on low idle and 0v when switched to high idle correct?

Last night I started going over all the wiring after I noticed the previous owner had tampered with at least one wire in there so I figured I might as well compare everything to the official wiring diagram as well as check for any damaged or exposed wires.
First thing I saw was the wire 200A coming from positive side of the brushes/slip rings had been spliced. That wire connects to positive on the diode rectifier bridge. For some reason though, someone spliced into the middle of that 200A wire and ran another wire from there to the on/off switch with an automotive style 15 amp fuse between the splice and the switch. I have no idea why you'd need this.

Next I noticed connections on the Ammeter didn't match the diagram at all. On the negative side of the Ammeter should be wire 209A that goes all the way to the starter solenoid. Instead I got 208A on the negative side thats going to the on/off switch. On the positive side of the Ammeter should be 208A coming from on/off switch then 208 going to 4 pin connector. Here instead I have 209A going to the solenoid and then 208 going to the 4 pin connector....kinda. This wire is actually labeled 208C and it goes to a lug on this little circuit breaker and then 208 connects on the other lug and goes all the way to the 4 pin connector. I looked for 208C in the diagrams and found it to be in the Honda CSA version of this machine (I have Kohler non csa)? It also had that circuit breaker. I'm guessing the PO got this from another machine with the Honda engine and put it on here for some reason. Anyway, the circuit breaker is tripped and pressing the button won't turn it back on so this connection has been broken the whole time. I'm just going to bypass this and have it just like the diagram. There's a few more things like wires 221 and 5H switched on the on/off switch and found one exposed wire that almost broken entirely which I'll have to fix. I'm basically just going to undo all the PO modifications and put everything like it should be on the diagram. I hope this thing doesn't blow up on me when I turn it back on. I'll come back here with updates after.

Here's the wiring diagram for reference:

[duaneb55]

So there should be 12v at the solenoid terminals when its on low idle and 0v when switched to high idle correct?

Correct. I'll comment on the other points later. Time for

[duaneb55]

First thing I saw was the wire 200A coming from positive side of the brushes/slip rings had been spliced. That wire connects to positive on the diode rectifier bridge. For some reason though, someone spliced into the middle of that 200A wire and ran another wire from there to the on/off switch with an automotive style 15 amp fuse between the splice and the switch. I have no idea why you'd need this.

This arrangement would allow the operator to provide initial excitation to the generator rotor for output. However, the control board would do this if fully functional. Is the switch momentary? If left closed after excitation, higher than 12VDC would back feed into the unit battery. A diode in the circuit would prevent this back feed but this modification never would be required if the control board were functioning properly.

Next I noticed connections on the Ammeter didn't match the diagram at all. On the negative side of the Ammeter should be wire 209A that goes all the way to the starter solenoid. Instead I got 208A on the negative side that's going to the on/off switch. On the positive side of the Ammeter should be 208A coming from on/off switch then 208 going to 4 pin connector.

This would simply make the ammeter register backwards showing a discharge condition when charging and visa-versa.

Here instead I have 209A going to the solenoid and then 208 going to the 4 pin connector....kinda. This wire is actually labeled 208C and it goes to a lug on this little circuit breaker and then 208 connects on the other lug and goes all the way to the 4 pin connector. I looked for 208C in the diagrams and found it to be in the Honda CSA version of this machine (I have Kohler non csa)? It also had that circuit breaker.

I wonder if the machine was originally powered by a Honda and a previous owner swapped it out for the Kohler. ???

I'm guessing the PO got this from another machine with the Honda engine and put it on here for some reason. Anyway, the circuit breaker is tripped and pressing the button won't turn it back on so this connection has been broken the whole time. I'm just going to bypass this and have it just like the diagram.

Again, I wonder if the machine was originally powered by a Honda and a previous owner swapped it out for the Kohler. You could leave it as is or reconfigure to match the non-CSA Kohler as desired.

There's a few more things like wires 221 and 5H switched on the on/off switch and found one exposed wire that almost broken entirely which I'll have to fix.

This reversed arrangement would still work properly as would matching the diagram.

What circuit designation is the "almost broken" wire?

I'm basically just going to undo all the PO modifications and put everything like it should be on the diagram. I hope this thing doesn't blow up on me when I turn it back on. I'll come back here with updates after.

You should be just fine by re-configuring to match the non-CSA Kohler diagram although I can't say it'll fix the idler behavior the unit is experiencing.

[abe79]

This arrangement would allow the operator to provide initial excitation to the generator rotor for output. However, the control board would do this if fully functional. Is the switch momentary? If left closed after excitation, higher than 12VDC would back feed into the unit battery. A diode in the circuit would prevent this back feed but this modification never would be required if the control board were functioning properly.

The switch is not momentary. Its just your regular toggle switch, double pole single throw (S3 on the diagram).

I wonder if the machine was originally powered by a Honda and a previous owner swapped it out for the Kohler. ???

Again, I wonder if the machine was originally powered by a Honda and a previous owner swapped it out for the Kohler. You could leave it as is or reconfigure to match the non-CSA Kohler as desired.

Could be, although I don't see any other evidence of an engine swap. The Honda diagram shows many more of those circuit breakers and I have only that one I mentioned.

What circuit designation is the "almost broken" wire?

That wire seems to be 224A. It goes from the hour meter to oil pressure switch. The copper is exposed and almost cut all the way through.

You should be just fine by re-configuring to match the non-CSA Kohler diagram although I can't say it'll fix the idler behavior the unit is experiencing.

I was hoping that restoring 208 connection (wire from Ammeter to B+ on voltage regulator) by bypassing that busted breaker would maybe be the fix I've been looking for...but I dream.