[MFleet]

This is a Generweld one thirty that has been around as far back as I can remember. It had a rod hanging out of the engine block. A friend is a machinist and casting repair specialist. He thought he could use it and repaired the engine a few years ago. The picture is not a proper presentation of his work. He couldn't get welding power out and gave up on it.

I've cleaned the mud dauber nest out of the points area and set the points to .20. The engine is now alive. I figured that the capacitor was bad and ordered a new 20 uf some time back. Still no output.

I found an old post on homeshopmachinist that recommended hitting the excitation coil with a battery charger. This did the trick! The best that I was able to get out of it on open circuit so far is 105V on the 120v outlet. The welding open circuit is ~45V IIRC.


"These older machine used residual magnetism in the generator to get things going. A current is induced in a special field winding where it is rectified and filtered and fed into the slip rings of the rotor. If they set too long there is no residual magnetism to induce any current in the excitation windings.

Just looked at the schematic. There is a capacitor, C1. Tough these terminals with a battery charger with the engine running. Positive to lead 10 and negative to lead 8. It just takes a second. You should hear the engine load up a little. Check the 120v out with a meter."


A new carb. has been ordered and a few other tune-up parts. Hopefully this will bring it up to full power. Any advise is appreciated.

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[JayWal]

Hats off to you man if you can get it going! I tried saving an old Acklands stick/tig tank of a welder I had sitting around. I gave up and gutted all the copper out of the windings and chucked it. Good luck!


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[MFleet]

All of the maintenance is done on the engine aside from installing the new points/condenser. The cheap carb. from amazon cleared up the rough running problems and it starts on the first pull. ~$45 for a very complete maintenance kit including carb. I've carefully popped the seal off on the stator bearing and put some fresh grease in it. The poor thing was completely dry.

Unfortunately the open circuit voltage and frequency is still low on the outlet and the 130A tap. All of it is roughly 2/3 what it should be. Bottom pics shows 76V@42Hz. I'm thinking that the next step is an inexpensive rpm/hour meter to verify it is at 3600 rpm. The slip rings and brushes may need some maintenance as well.

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[noddybrian]

Assuming it's a conventional generator & the AC is being produced by a 2 pole alternator I think it's safe to assume the governor RPM's is off by the difference in frequency of 42 > 60 so proportionately the volts will be down a similar amount as this unit looks too old to run an AVR - so a cheap way to establish actual RPM is the next step - probably it's as simple as a tired spring - from other generators I've played with there is every chance once you get the revs right it will work fine - it's normal to have the revs set under no load around 10 > maybe 15 % over to allow for drop once under load as air cooled petrol governors are not noted as being that accurate. interesting find / restoration .

[MFleet]

Your diagnosis is correct, Dr. Brian. Definitely a pre-AVR model.

I've found that I already had an rpm meter right there in my hand. With a cheap lead wrapped around the plug wire, the first picture shows the same 42Hz that we saw earlier. 42 x 60 = 2520 rpm. It needed a good amount of adjustment to the governor spring tensioner. The last picture shows a perfect 60Hz under load. The OCV max. on the 130A out was slightly higher @68V compared to the 65V spec. in the manual. It is starting to look like it will create a nice arc again

There is a faint glow inside of the muffler at full rpm. It can't be adjusted out with richening the high speed needle. From what I've researched, this is indicative of needing some minor exhaust valve work? The points gap was set with piston 1/4" past TDC. I couldn't find a cam mark on it.

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[noddybrian]

Glad it's all coming together for you - volts sound about right - they are rarely that precise on those machines - even when new I think they all got stamped with a number from a singular test model - not specific to that unit on test at build - when you say timing set past TDC you do mean before TDC right ? can't make out the engine enough in the pictures to know what it is but they would'nt have had much spark lead on what I assume is a side valve - usually on Briggs / kohlers etc there was a small cast mark on the flywheel indicating points opening position - maybe a google search on the engine will give you some help - can't wait for an arc shot of it back in life.

[MFleet]

Yeah, I screwed up the points setting. It is a Tecumseh HM80. Found a technicians handbook for download that has the specs. All of the below has been checked or set with the new points installed. It turns out that the points setting is an initial step for setting the timing. If the points are changed or the adjustable stator assembly/timing has been disturbed, it needs the timing set.

I still have some faint glowing in the muffler baffle, intermittent misfire, and dry carbon fouling on the plug. The misfire happens at idle and full rpm. I'm thinking that the next potential items are leaking wire insulation, weak coil, or bad laminations. Hopefully the valve seats are in good shape.

Plug gap: .030
Points gap: .020 at top of cam lobe.
Timing: .090 BTDC. Requires an offset indicator tip to reach the piston.
Valve clearance at TDC: int .008 and exh .012
Flywheel magnet pull tested good out to 1/4"
A cold compression test registered ~60+ psi

This explains the timing procedure very well. https://www.youtube.com/watch?v=axCzcFI4kek

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[nailbanger138]

I know this is an older thread, but I just picked one of these up. I have some questions about the output side of things, and it seems like you have a pretty good handle on the issue.

[MFleet]

I know this is an older thread, but I just picked one of these up. I have some questions about the output side of things, and it seems like you have a pretty good handle on the issue.

Post up the questions. Shoot me a p.m. if you find any hangups.

[nailbanger138]

My main questions are pertaining to the capicitor and diodes. I haven't had time to thoroughy troubleshoot, but the little I did, the voltage to the receptacle and weld leads was very low, and the capacitor tested bad. I have found a replacement capacitor, but suspect I may need the diodes as well, a source or model for those would be great. Also, did you have to hook up the battery charger as I've seen suggested to bring back the magnetic field?

[nailbanger138]

My main questions are about a source for the diodes, and difficulty of installation. Also did you have to hook up a battery charger to bring back the magnetic field? Thanks in advance.

[MFleet]

My main questions are about a source for the diodes, and difficulty of installation. Also did you have to hook up a battery charger to bring back the magnetic field? Thanks in advance.

What is the voltage on the outlet and on the output lead connection?

Some of my pictures seem to be missing from the thread. Have a look at this one and that should explain everything. Yes, hit the exciter with a battery or old analog type charger for a quick second as described in the first post. Most multimeters have a diode check setting, so give that a go first. I doubt that they are bad as they are not stressed in this circuit. Did you find the pdf manual for it? I think it was available on the Miller docs site.

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[nailbanger138]

Finally had some time to work on this. I got the motor running well, and I can set the idle to desired rpm. I am going to test teh power output now, my cap tested bad, so I am putting a new one on out the gate. If the excitation circuti needs a bump from teh battery charger, my only question i sdo you do this with everything hooked up? Or do I need to disconnect the appropriate leads fro,m the cap to hit them with the battery charger. Thanks again for the input.

[MFleet]

Yes, fully assemble it and start the engine if you need to apply the charger. You stated that you had low output, so the excitation circuit was working on some level.

Low output troubleshooting:
Needs 3600 rpm at "weld" throttle setting. Can also be verified with a multimeter as 60Hz on the 120V receptacle.
Connections are clean and snug?
Check that brushes are good and rings are clean.