Miller 1E Welder/Generator now running!

[Tom Reed]

Since we've had a break in the fires I've had some time to complete the rebuild on the K301 engine on this welder. It now runs like a top. Now if it would only generate some power I'd be a happy camper. I've got nothing anywhere. The slip rings, outlets, dc out to the bat and welder connections, no power.

The first plan of action is to clean the slip rings. Looking at the attached schematics, a coil under the flywheel should provide initial excitation voltage so flashing the field windings should not be necessary, right? If so I guess it should be checked for the presence of AC on that line.

The schematics are the attached JPG file.

[Tom Reed]

Ok I checked for ac voltage from the coil under the flywheel. None was detected. The coil ohm'ed out at .75 ohms. Is it time for a new coil?

[mobile_bob]

i don't think, and it appears my thinking is correct according to your schematic
that the coil under the flywheel does battery charging for the starter system and is not needed for excitation of the welder/generator.

the welder is self excited

a few other thoughts

check the toggle switch on the main panel, it might be corroded
check the resistor, the adjustable one, it might be corroded too.

check all spade terminals, some of them might be loose and not making good contact.

the machine is very simple in design, and pretty easy to sort out in my opinion.

bob g

[mobile_bob]

Tom

the slip rings need to be clean, if they are brown or blackened it won't start
to generate or weld.

also check the individual diodes, D12, D5 and D6

on my 1E which is '67 vintage one of those diodes was very hard to find
it was slid up inside a piece of insulating sleeve along with a couple other wires and was very hard to find,, mine failed open and the machine was dead.

a 99 cent 2pack from radio shack and back in business again, this time however i left the diode outside the loom/sleeve.

in my opinion, for what the 1E is, it is the finest portable welder ever conceived by man!  they run forever !

also of note, you can replace the ignition system with a standard 12volt coil
and condenser from an old chevy, along with the ballast resistor. this makes for an engine that will start no matter how cold it gets.  the kohler point set works just fine with the upgrade coil/condenser/ballast resistor.

one other note, on mine the throttle has a set of microswitch's that trigger the machine to power only when you are running at idle ~1950 no load rpm, and then switch over to weld when you open the throttle to full throttle

it might be the micro switches are a bit funky, so check them out too. mine are original equipment units and have never failed or given any problem at all, but it is possible.

i would start with the slip rings, if you are very careful you can clean them with a bit of sandpaper taped over a tongue depressor or popsicle stick with the engine running,, just run it over the slip rings until the brighten just a bit.. no need to remove a bunch of copper and they don't need to be fully bright like a new penny...

good luck!

bob g

[Thob]

No AC at all, not even a few volts?  Then it probably needs to be flashed.

It looks like to me that wire #9, "Pulse coil lead", from the ignition provides initial power for the field thru diode D5.  If the ignition has been modifed, this may not be present; or diode D5 could be bad.

+12V DC applied to the ungrounded slip ring should give it enough magnetism to get it going.

[Tom Reed]

Ignition is stock. Output, or lack there of, was measured at the lead that comes out from behind the flywheel before it connects to the circuit board.

[vdubnut62]

There "should" be a diode in the wire from under the flywheel too(it keeps the alternator winding from discharging the starting battery when not running). It'll probably be hidden under an insulating piece of woven loom type stuff. I've cussed 'a many of em.
Ron
Oh, and "Have patience, Grasshopper".

[Tom Reed]

The diode is shown in the circuit is D5 which is on the circuit board and it tests as good. The slip rings were cleaned and I tried flashing it last night, still no joy. I am measuring continuity on the exciter coil so the circuit is not open, it looks like the coil is shorted to ground since from ground to the lead out from behind the flywheel measure .75 ohms.

[Thob]

1) Measure the resistance of the field winding at the slip rings.  Should be on the order of a few ohms, or tens of ohms.  If it's much larger than that, I would suspect the field is open.

2) Measure the resistance from brush to brush.  It should be similar to the field resistance from step 1.

3) Check Diodes D12 and D6, make sure they are not shorted.

4) Take the lead from the ignition loose (the wire from "engine ignition" to D5) and apply +12v to D5 with the machine running.  USE CAUTION HERE.  Measure the AC voltage at the power outlets and welding terminals.

Let us know what you find...

[Tom Reed]

1) Measure the resistance of the field winding at the slip rings.  Should be on the order of a few ohms, or tens of ohms.  If it's much larger than that, I would suspect the field is open.
25 ohms

2) Measure the resistance from brush to brush.  It should be similar to the field resistance from step 1.
19 ohms

3) Check Diodes D12 and D6, make sure they are not shorted.
-[ |    ]+ D6 neg to neg 30 ohms, neg to pos 25. D12 was 25 ohms in both directions.

4) Take the lead from the ignition loose (the wire from "engine ignition" to D5) and apply +12v to D5 with the machine running.  USE CAUTION HERE.  Measure the AC voltage at the power outlets and welding terminals.
Please inform as to what to be cautious of before I let the magic smoke out. I did flash 12vdc to this wire with engine running with no results other than a good spark.

Let us know what you find...
Also wire #18 at S1 has a loose terminal at the switch and the connection is intermittent when wiggling the wire. Looks like I'll need to jumper wire #2 to #13

[mobile_bob]

if this machine was mine, and based on my experience with dozens of the 1E . 2E and AEAD miller welders

check ever single connection on the inside of the machine, all those spade terminals, check all screw terminals, check continuity of all switches and microswithes, check all diodes.

the only way to check the switches and microswitches it to disconnect them from the circuits they control, so you don't end up checking continuity of the circuit and not the switch contacts

same goes for diodes, they must be removed from the circuit, at least one leg must be dangling free or else you will not get a good test because you are getting erroneous readings from other parts of the circuit.

check the brushes and slip rings, one lead must also be removed from the control circuits, otherwise you are not going to get a continuity of the rotor and brush to rotor readings, but a reading that includes other parts of the circuits.

over half the time it is a dirty slip rings or crapped up brushes, so clean them up
what reads ok shut down might well not read so when running.

probably 25% of the time it will be a loose spade terminal connection or some other loose connection, so you must check them all.

a fair amount of time there is an "open" diode, not shorted but open, so you must find and check them all, even those that are hidden away inside of looms.

then there are the switch problems, as these machines are not getting to be quite long in the tooth, all switches are suspect and should be checked and replaced if there is any doubt as to their consistency of operation.

i am still not at all convinced that the machine needs excitation from the ignition system it order to excite the rotor, mine does not!  i removed all the oem ignition
system and used the oem points to trigger a chevy coil, condenser and ballast resistor.. there is no interconnection with the generators excitation system at all, it will self excite no problem at all.

in my experience, while it is possible you have a generator failure, i find it to be very rare occurrence.  it has always been some 2 buck part or a loose wire in my experience, and once found puts the unit back in service quickly and cheaply.

bottom line, start with all the obvious, check every connection then work down the list testing individual components.

my bet is it will turn out to be something very simple that is staring you in the face.

bob g

[Tom Reed]

I'm in the process of ordering a new switch. If the diodes need to be pulled out of the circuit, I might as well replace most of them with a modern bridge rectifiers. I agree with your assessment Bob. Fortunately there is nothing charred and stinky under the cover.

[Thob]

I suspect one of the diodes is shorted, possibly one of the caps is shorted instead.  As  Bob says, you'll need to take them out of the circuit to check them.  Can you disconnect the board from the generator?  Or is it all soldered?  If you can disconnect the board, that should isolate the diodes enough to check them.

[Tom Reed]

The wires are attached behind the board, I'll take a look. I found a great deal on a surplus Cutler-hammer switch to replace the defective one. The loose terminal on wire 18 is part of the exciter circuit. Once this is fixed I believe I should be able to measure some voltage on the Z winding. When that is working then I can see where power is and isn't.