I bought this generator a few weeks ago, used. It worked fine, but stopped putting out any power. I contacted repair people, the local repair facility only works on bigger units, but the man said it was most likely the voltage regulator. Got the regulator on line and installed it, I get power now. The 120v recepticles put out 50 v. and the 220 put out approx. 120v. Any ideas, suggestions, referals? Thanks.
1 The new regulator is faulty. 2 You installed it improperly.
Ellombris-
I have downloaded some Generac manuals from
The 83970 has a trim pot that sets voltage. Some models have the board mounted with the trim pot next to a rubber plug on the left side of the connector panel. If your model has this board, it might easily be misadjusted. Try adjusting it for an initial value of 124 Volts output with no load. A small adjustment can make a large difference in output!
There is also an 84132, called a "Power Regulator Board" on the diagram and "Assembly, Drive Module, Power Regulator" on the parts list. This module controls current to the rotating field. It has no adjustment itself, but is driven by the System Control Board. Was that the module you replaced?
If you study the problem further and still can't solve it, check out the "Generators and Motors" forum at
Fred
The unit I have is a 7500 not the 5500, and I do have a parts list and schematic for this generator. Thank you for your advice. I spoke to a tech for the local company that works on larger units and he told me, the 84132 has an adjustment screw on it. That is what I'll be trying next. My kid works nights so I won't be running the generator 'till Sunday, his day off. Thank you you for your help, if this works I'll post that The problem is solved, if not I'll be begging for help again and will check out the websute you suggested.
Ellombris-
My mistake. Somehow I read 7500 and thought 5500 when looking at my collection of downloaded manuals!
Other Generac generators use the same set of boards. If yours has the
84132 module (located in the end bell of the generator, connected to the brushes), it most likely also uses the 83970 module (located inside the connector panel assembly). They work together to regulate voltage.I have a set of manuals (Clymer "Small AC Generator Service Manual", volumes 1 and 2). Volume 2 covers Generac fairly thoroughly. One section leaves me with the impression that the 83970/84132 module pair is used for all models that have the idle control circuit, from 3500 to
7500 Watts.Fred
Hi...
Just playing the devil's advocate for a moment...
Difficult to tell where any of us are in the world, so can't even guess at where you might be, but those just about 1/2 voltages might not be a coincidence...
It's not possible that you're in the UK and bought a North American regulator, is it? :)
Take care.
Ken
OK ! I'm in the US and this unit worked when I bought it used, I was wrong about the voltage regulator. I have the used one I replaced and the screw is not to adjust the voltage, it's to secure the heatsink to a component on the board. I looked on the side of the output panel and found the adjustment on the 83970 and adjusted it. The most voltage I get out of the 120 0ut is 68v and I adjusted the trim to give me 120 out of the 220 receptacle. That gives me 60v out of the 120 outlets. This unit uses a rotor and a stator, so I can't see how it would have fields. The original diagnostic by a friend who is an electrical contractor was that one of the fields might be bad, therefore the 1/2 power. I read something about flashing the fields, but don't think this applies to me. I was told by the local tech that repacement rotors and stators are usually 2 to 3 hundred bucks, before the labor costs. It would be nice to find a unit with a blown engine, buy it and swap out the generator. Any more advice is welcome, and thanks to all.
Ellombris-
If you needed to flash the field, there would be NO output, so don't worry about doing that.
Have you inspected the brushes to see if they might be worn down or have a frayed wire that might be touching the frame?
A shorted battery charger rectifier diode might cause low output, but probably wouldn't zap the 84132 module.
Some 7500 Watt Generac models had winding resistances in Ohms as follows, per the Clymer volume 2 manual:
Rotor 7.6-9.1 Main AC Power .20-.25/.20-.25 Excitation(Dpe) 1.56-1.91 DC Battery Charger Winding .05-.09/.06-.11
The Excitation (Dpe) winding supplies AC voltage to the 84132 module, which rectifies it and supplies current to the field via the brushes.
If you have time, visit
Fred
Sounds like a split 240 generator. Perhaps the regulator connections got switched to the 240 leads instead of the 120 leads?
Wouldn't they only go to the 240 leads? If that output is correct, the
120 should be as well.
You'd think but who knows? Without a circuit it's hard to diagnose.
I have no experience with a generator of this size, so this may not be relevant.
When my 2500-watt generator suddenly quit, I opened up the end bell and found that there were a pair of stud-mounted power diodes inside. One of the diodes had shorted, with the result that there was zero voltage at the output. I'm not sure of the function of the diodes, but I think they provided DC (unipolar) excitation to the field coils.
My generator was 120VAC only (no 240VAC). Perhaps yours has lost one side of the 240VAC excitation, resulting in half voltage somehow.
Just FWIW.
Bill
--------------------------
James Sweet wrote:
Homer-
If you're interested, an owner's manual with a circuit that may be similar to this one, can be found at
The file is a little over a megabyte.
Fred
Thank you Fred. I have the parts and exploded diagrams for this unit.I have schamatics for it also. The problem is I know just enough about electricity to be dangerous. For instance the specs given for the windings. I have an ohmmeter and can read it, I just don't know where I'd attach it to get the readings. In the process of replacing the voltage regulator I unscrewed the brushes assembly for access to attach
2 wires from the voltage regulator, and I think I seated the brushed right. I will check this tomorrow, Monday. Thank you all.
One thing I forgot to mention, was that your symptoms might be caused by having the Idle Control Switch turned ON. With no load, the engine goes to a lower RPM, perhaps equivalent to 40 Hz, and voltage goes down somewhat.
Do you have capability to measure frequency or RPM? The generator probably runs at 3600 RPM to produce 60 Hz. (Some run at 1800, but I don't think yours does.)
A problem measuring resistance of generator windings, is that the resistance is so low that meter leads and their contact resistance can be a higher value than the winding being measured!
The brushes ride on slip rings, which are connected to the rotating field winding. You can measure field resistance by disconnecting the regulator and measuring across the brushes. If resistance is too high, it could be a problem with the brushes as well as the winding. With the brush assembly unscrewed, you may be able to probe the slip rings directly.
The main winding connects via circuit breakers to the electrical outlets. A 240 Volt outlet will have connections to the three main wires (120-0-120). I don't know how much influence the breakers would have on the measurements.
The excitation (DPE) winding connects to the regulator module as I recall.
Fred
Bill says maybe I lost half my excitation. That's exactly what I'm thinking. Do I need to run the generator to flash the fields? I'm thinking I disconnect the leads from the volage regulator @ the brushes so I don't burn it out and take a 12v battery, connect the ground to the chassis and the positive to one of the brushes for a second and then do the other brush. If I understand what they are saying on smokestak. Or maybe someone can walk me through flashing the fields so both are remagnitized, and I'll run it for an hour to get the magnetism to stay??
I would have great difficulty believing you need to flash any field magnet these days - this isn't a Model A Ford. Look elsewhere.
If you lost half excitation, I'd go looking for a bad diode.
Ellombris-
NO. When the field needs to be flashed there is no output at all. If there is ANY residual magnetism, there will be output, and almost instantly it will build up to full value when you start the generator.
Something else is causing your problem.
Could it be the Idle Control switch is set to the "ON" position? That would give your symptoms until you connect a load to the generator output. If you connect a light bulb to the generator, does it light to full brightness, or barely at all?
The diodes that rectify field current are in the module you replaced. Unless it has an open diode, it is unlikely to be the problem.
When you installed the module, could you have connected the wires to the brush assembly backwards? According to the Clymer manual, the White wire connects to the positive brush, which is the one closest to the bearing.
Fred
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