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Onan NHDFB 1M spec M


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  #11  
Old 08-30-2017, 02:28:01 PM
len k len k is offline
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Default Re: Nhdfb 1M spec M

Thank you Kpack for the reg and choke.

Anyone ever measure the AC voltage output of PMG with no load on it? Guessing it's around 30 VAC
(PMG = permenant magnet generator under flywheel)

I looked in NHD service manual 965-0500:


Likely PMG
paper page 87..... b. If (PMG) winding continuity is good, connect an AC volt meter to the PMG stator leads, start the engine, hold in the Start switch and immediately pull off the wire connector at starter solenoid terminal S to disengage the starter. Replace the flywheel assembly (Figure 9) if the output is less than 29 VAC.


Likely B windings in stator.
paper page 47 ........ Battery Charging Regulator (VR2): The battery charging regulator recharges the battery while the genset is running. It is connected to generator terminals
B1 and B2 which provide power to the regulator at 19-21 VAC. The regulator limits output to 10 amps.

Likely PMG but doesn't give winding AC volts.
paper page 45.......Battery Charging Regulator (VR2): The battery charging regulator recharges the battery while the genset is running. It is connected to the PMG. The regulator limits output to 14.2 volts and 10 amps.

Last edited by len k; 08-30-2017 at 02:38:32 PM.
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  #12  
Old 08-30-2017, 05:57:05 PM
Vanman Vanman is offline
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Default Re: Onan NHDFB 1M spec M

If one needed to use that stator (armature) on a set that requires the B winding, a suitable small transformer could be used in place of the B winding. 120 or 240 volt to something close enough to B winding normal output.

In using the regulator on a set with fixed resistance charging, I would imagine that it may be good to leave some resistance in the circuit, ahead of the regulator, so that it doesn't need to drop as much voltage, particularly when the charge current is high.
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Old 08-30-2017, 07:58:24 PM
len k len k is offline
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Default Re: Onan NHDFB 1M spec M

My plan is to put a bat on reg and power reg with a variac and transformer. From zero ramp up voltage going into reg to PMG voltage, while watching current on reg input and output. Want to figure out if it's a shunt reg or not, if it's a shunt type it'll draw lot more amps from transformer than it supplies to bat when bat is charged.

Then if it's not a shunt reg I'll try 14.8 VAC input to reg. (14.8 VAC had a peak of ~ 21 V). That's voltage I think my 7NHM makes out the B windings, I just ratioed it from following. ( with no AC reg and 12.2 VDC to field I got 56.7VAC out 120 windings and 7.0 VAC out B windings)

When using DC reg you wouldn't use a resistor, if reg is not a shunt type. If it is a shunt type I'll experiment with how much series resistance I'll have to add to B windings so I don't fry DC reg or B windings.

Last edited by len k; 08-30-2017 at 09:03:24 PM.
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  #14  
Old 08-31-2017, 07:13:39 AM
Kevin K Kevin K is offline
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Default Re: Onan NHDFB 1M spec M

The voltage output of my NH Aux PMG is 26VAC no load. I didn't think to measure the frequency, but next time I start it I will get back to you. I will take the voltage reading again with a different meter. The meter I used was not an RMS type, and may not be accurate at other than 60Hz.

I'm guessing your regulator is single wave series pass with one SCR, based on Magnetites drawing.
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Old 08-31-2017, 11:01:11 AM
len k len k is offline
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Default Re: Onan NHDFB 1M spec M

Chances are Onan used the same PMG design in all their gens.
From pic in posts 6 & 7, NH & NHD used PMG with 18 poles @1800rpm ........so 270 hz I believe.
I remember Magnetite saying it was in the 200's also.
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Old 01-11-2018, 05:07:55 PM
len k len k is offline
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Default Re: Onan NHDFB 1M spec M

Finally have some low car bats that need charging. So good time to check how DC reg Kpack sent me behaves over a full bat charging cycle. I'll need 30 VAC, but pretty sure I have a 30V transformer powering cat's outdoors house heater I can borrow. (water bed heating pad).

Was convenient so I hooked reg up to a power supply I have that outputs 13.2 VAC @ 60 hz
Bat voltage before charging was 12.15 VDC and was 12.27 VDC while charging.
AC current drawn by reg was .923 amp (RMS) and DC current to bat was .679 amp

-------------------------------

Likely won't bother since don't need it, but it occurred to me I could test reg with 30VAC at 270 hz sinewave instead of 60hz. I've got an old high power stereo 2 X 250 watt rack mounted bass amp I fixed. Could feed amp the signal from sound card of computer running recording studio software, sinewave frequency generator. Guessing in mono mode amp would have no problem providing 30 VAC at 15 amps .......MASSIVE HEATSINKS and many paralleled output transistors. Onan reg says 14V, 20 amp on it.

Amp = Carvin MFG, Co. #ASG500

Last edited by len k; 01-11-2018 at 06:40:57 PM.
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Old 01-11-2018, 07:16:20 PM
Kevin K Kevin K is offline
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Default Re: Onan NHDFB 1M spec M

If you get a chance Len, could you check with a scope to see if it is a half wave or full wave regulator/rectifier?
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Old 01-11-2018, 11:16:22 PM
len k len k is offline
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Default Re: Onan NHDFB 1M spec M

Sure , no problem. When I set it up I'll drag scope out of cellar. It's only an AC coupled scope but it'll do for this.
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Old 01-12-2018, 06:19:21 AM
armandh armandh is offline
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Default Re: Onan NHDFB 1M spec M

checking the AC voltage from the PMG no load is near useless [IMHO]
I would rectify it and charge a battery with it and see the current/voltage
put a head lamp in series to test if you are worried

my Kohler K-582 uses a similar regulator for battery charging, ignition power.

if you plan on using a zero center amp meter
the regulator and load go to one side
battery to the other.
if the sides are connected in reverse it will read backwards
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Last edited by armandh; 01-12-2018 at 06:29:45 AM.
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Old 01-13-2018, 05:14:17 PM
len k len k is offline
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Default Re: Onan NHDFB 1M spec M

Reading between the lines but Looks like spec J and above had PMG under flywheel and DC reg 191-2139 ($20).
While spec H and guessing specs A to I had B windings in stator and used DC reg 305-0784 ($225)


From post 11: NHD service manual 965-0500 page 87 says when engine is running and j8 connector to PMG is opened should get at least 29 VAC (no-load) out of the PMG winding under flywheel.

Then paper page 47 it says B1 and B2 which provide power to the regulator at 19-21 VAC. . Odd, sounds like this is for gens with B windings in stator like spec H (not PMG winding under flywheel). Oh well, to be safe I could add a ~1 ohm series resistor on AC input to DC reg, that way under 10 amp load input voltage to reg will be down to ~ 20VAC from 30VAC.

----------------------------------

Oh well, I'll try supplying DC reg with 30 VAC @ 60hz from a transformer I have plugged in wall. I'll add a resistor in series with just in case reg is a shunt type so I don't burn it out.

Manual says reg limits output to 10 amps (paper page 47) and 14.2 VDC.
I'll have to run a cold test later to see if reg is temperature compensated , see if voltage changes at cold temps.

The DC reg has these numbers printed on it Onan 191-2223, 14V, 20 AMP

Last edited by len k; 01-13-2018 at 05:38:19 PM.
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