Marathon MagnaPLUS Series Operating instructions

MagnaPLUSGeneratorTroubleShootingGuide(SP0023).docx12/27/2018TRS 1 
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Trouble Shooting – MagnaPLUS / Mariner / Harsh Duty
MagnaPLUS / MARINER / Harsh Duty models are 12 lead, re-connectable, brushless, AVR regulated
generators. For simplicity, MagnaPLUS refers to all three product lines. A listing of models and
specifications is included at the end of this trouble shooting guide.
A MagnaPLUS generator is simple to trouble shoot with 6 main components: the exciter stator and
exciter rotor windings, a voltage regulator, a rectifier assembly, and the main stator and rotor
windings. For tools you will need a good multi-meter – a Fluke works very well – a ratchet set, and a
set of screwdrivers. You can make an analog style meter work as well.
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Figure1
This trouble shooting guide addresses the most common causes of low or no output voltage, usually
15V – 50V as measured at the generator terminals, mounted on the linkboard located in the connection
box mounted on top of the generator.
Start trouble shooting in the connection box mounted on the top of the generator. It gives easy access
to the exciter stator leads ( F+ & F- ) and main stator output leads.
If your generator is equipped with a PMG Excitation Support system refer to the section on PMG
Powered Regulators on page 6.

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If the generator has been sitting, unused, for 3 – 6 months, or longer it may have lost its residual
magnetic field required to build voltage. In this case, refer to the section on Restoring Residual
Magnetism on page 5.
SAFETY NOTE – Dangerous Voltage May Be Present During Testing
Step 1 : Check Exciter Stator Continuity and Resistance
SAFETY NOTE – Exciter stator testing must be done with the gen-set shut down.
Disconnect exciter stator leads F+ & F- from the voltage regulator – red and black leads in
Figure 2. Using meter check continuity between F+ & F-. If you have NO continuity
between F+ & F- , you have a failed exciter stator winding.
Switch meter to auto-ranging Ohms setting and check resistance between F+ & F-. If exciter
stator resistance does not match the specifications table value within ± 5 Ohms, you
have a failed exciter stator winding.
Figure2
Switch meter to auto-ranging Ohms setting check continuity between F+ and generator ground.
You should have at least 5 megOhms of resistance between the exciter stator and ground. If
you HAVE continuity between F+ and generator ground, or < 5 megOhms of resistance,
you have a failed exciter stator winding.
A failed exciter stator cannot be repaired. Replace Exciter Stator

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Step 2 : Constant Excitation Test
SAFETY NOTE – Constant Excitation test MUST be done with the gen-set running.
Conduct constant excitation test, only if Exciter Stator passed all tests in Step 1.
Disconnect exciter stator leads F+ & F- from the voltage regulator – see Figure 2 – and
observing polarity, connect to a 12V battery. The gen-set starting battery can be used as the
source of constant excitation.
Run the get-set, no-load with all breakers switched off. Measure output voltage at output
terminals: A – B, B – C, and C – A shown in Figure 2. A well-charged battery should give nearly
full output voltage – refer to specifications table by model – possibly a bit more. Voltage should
be balanced between all three phases.
Possible Constant Excitation Test Results
Results Possible Corrective Action
Output voltage is balanced and within
expected range. ( -10% – +15% ) Voltage Regulator has failed and must be replaced.
Output voltage is well below expected
range.
One or more diodes have failed.
Replace Rectifier Assembly is preferred action.
ALL diodes may be replaced individually.
Output Voltage ≤100V Multiple component failures. Replace generator.
Output Voltage is Unbalanced Main stator has failed. Replace generator.
Step 3 : Check Main Stator Windings
The main stator windings are very low resistance which makes them difficult to field test. Set
meter to the lowest possible Ohms scale and measure resistance at output terminals: A – B, B –
C, and C – A shown in Figure 2. You must have good continuity and should have a balanced
resistance reading between phases. Refer to Specifications Table for resistance by model.
If you have NO continuity or resistance readings vary significantly – anything higher than about
1 ohm for most models, you have a failed main stator winding.
Set meter to the highest possible Ohms scale. Check for continuity between output terminals
and the ground terminal. Resistance should be greater than 5 megOhms or infinite. If you have
continuity or < 5 megOhms resistance between the main stator leads and the ground terminal
the main stator is faulted to ground.
Failed main stator windings cannot be repaired. Replace generator.
If testing STEPS 1 - 3 have not found any faults or defects, move to the opposite drive end of the
generator to check the diodes on the rectifier assembly. You will need to remove the back cover to gain
access to the rectifier assembly. It is not necessary to remove the exciter rotor.

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Step 4 : Checking Diodes / Rectifier Assembly
The diodes may be tested in place. Remove the two main rotor leads (B) and the three exciter
rotor leads (A) from the rectifier assembly – see Figure 3. Note the location of each lead for
proper reassembly. The diodes are now isolated from the generator and may be tested.
Figure3
Multimeter Diode Test : Switch multimeter to diode test mode, place one lead on the top of a
diode, the other lead in contact with corresponding main terminal post. Test each of the three
FORWARD diodes in turn. Reverse test leads and repeat. A good diode will have no voltage
reading in one direction and 0.4 – 0.5Vdc in the other.
Repeat testing procedure for the three REVERSE diodes.
No voltage in either direction or voltage in both directions indicates a failed diode.
OR
Analog Meter: Place one lead on top of a diode, the other lead in contact with corresponding
main terminal post. Test each of the three FORWARD diodes in turn. Reverse test leads and
repeat. A good diode will have much greater resistance in one direction. Typical forward
resistance is under 100 Ohms. Typical resistance in the reverse direction is over 30,000 ohms.
Repeat testing procedure for the three REVERSE diodes.
Continuity with little or no resistance in both directions or very high resistance in both
directions indicates a failed diode.
Failed diodes must be replaced. Replace Rectifier Assembly.

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Field Flashing / Restoring Residual Magnetism
If the generator has been sitting, unused, for 3 – 6 months, or longer it may have lost its residual
magnetic field required to build voltage.
12V Dynamic Field Flash
SAFETY NOTE
– The Dynamic Field Flash MUST be done with the gen-set running.
Disconnect sensing & power leads 3 & 4 from the voltage regulator – as indicated in Figure 4.
Insulate and isolate leads for safety.
Disconnect exciter stator leads F+ & F- from the voltage regulator – as indicated in Figure 4
and observing polarity, connect to a 12V battery. The gen-set starting battery can be used.
Run the get-set, no-load with all breakers switched off. Measure output voltage at output
terminals A – B, B – C, and C – A shown in Figure 4. A well-charged battery should give full
output voltage – refer to specifications table by model – possibly a bit more. Voltage should be
equally balanced between all three phases.
If output voltage comes up to normal range, run generator for 15 minutes to build residual
magnetism.
Figure4

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PMG Powered Regulators – PM500 & Marathon DVR
The PMG Excitation Support System consists of a permanent magnet rotor, wire wound stator, a 7.5
microfarad capacitor and appropriate voltage regulator. The PMG system provides an isolated power
supply to the voltage regulator which provides assured voltage build-up for critical applications.
Check the Capacitor
SAFETY NOTE
– Discharge the capacitor by shorting terminals with insulated jumper
wire or screwdriver with insulated handle.
Digital Multimeter: Disconnect leads from capacitor as shown in Figures 5 & 6. Switch
multimeter to the capacitor setting, and directly check the capacitance reading. If capacitance
is significantly less than 7.5uf, you have a failed capacitor that must be replaced.
OR
Analog meter: Disconnect leads from capacitor as shown in Figures 5 & 6. Switch meter to
Ohms x 1000 scale. Touch leads to the capacitor terminals – you should see the resistance
start very low, near zero, gradually increase towards infinity and then return back to zero.
Discharge capacitor, reverse leads and repeat. If you do not see the charge / discharge
pattern, you have a failed capacitor that must be replaced.
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Figure5

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Figure6
Check PMG Stator Continuity and Resistance
SAFETY NOTE – Exciter stator testing must be done with the gen-set shut down.
Disconnect leads from capacitor as shown in Figures 5 & 6.
Using meter check continuity between the two PMG stator leads. If you have NO continuity
between PMG stator leads, you have a failed PMG stator winding.
Switch meter to auto-ranging Ohms setting and check resistance between the two PMG stator
leads. If the PMG stator resistance does not measure between 1.9 – 2.3 ohms, you have a
failed exciter stator winding.
A failed PMG stator cannot be repaired. Replace PMG Stator.
Once the PMG Excitation System has been verified, continue trouble shooting at STEP 1 on page 2.
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MagnaPLUS / MARINER / Harsh Duty
3 Phase 480V Generator Specifications
MagnaPLUS
Model Main
Stator Main Rotor Exciter Stator Exciter Rotor
No Load
Excitation
480V / 60Hz
Mariner /
Harsh Duty
Model
281CSL1500 4.2 0.4 18.0 0.120 11 n/a
281CSL1501 4.15 0.4 18.0 0.120 11 n/a
281CSL1502 0.47 0.72 18.0 0.120 6.4 n/a
281PSL1722 3.2 0.439 18.0 0.120 9 281PSL28040
282PSL1703 1.07 0.34 18.0 0.120 14.7 282PSL28041
282CSL1504 1.24 0.8 18.0 0.120 6.2 n/a
282PSL1704 1.07 0.34 18.0 0.120 14.7 282PSL28042
282CSL1505 0.87 0.9 18.0 0.120 5.8 n/a
282PSL1705 0.74 0.37 18.0 0.120 14.35 282PSL28043
283CSL1506 0.54 1.00 18.0 0.120 8.2 n/a
283PSL1706 0.45 0.4 18.0 0.120 12.95 283PSL28044
283CSL1507 0.44 1.18 18.0 0.120 9.2 n/a
283PSL1707 0.39 0.46 18.0 0.120 11.2 283PSL28045
284CSL1508 0.29 1.36 18.0 0.120 10 n/a
284PSL1708 0.27 0.52 18.0 0.120 14.18 284PSL28046
284CSL1542 0.27 1.36 18.0 0.120 8.3 n/a
284PSL1742 0.22 0.54 18.0 0.120 14 284PSL28047
285PSL1700 0.2 0.58 18.0 0.120 11.9 285PSL28048
286PSL1701 0.14 0.72 18.0 0.120 10.68 286PSL28049
287PSL1702 0.12 0.79 18.0 0.120 10.9 287PSL28050
361PSL/CSL1600 0.381 0.75 23.5 0.120 11.8 361PSL3120
361PSL/CSL1601 0.264 0.81 23.5 0.120 12.5 361PSL3121
361PSL/CSL1602 0.181 0.99 23.5 0.120 14.1 361PSL3122
362PSL/CSL1604 0.138 1.05 23.5 0.120 12.2 362PSL3124
362PSL/CSL1606 0.098 1.2 23.5 0.120 10.8 362PSL3126
363PSL/CSL1607 0.069 1.37 23.5 0.120 12.2 363PSL3127
431PSL/CSL6202 0.021 0.811 18.5 0.120 15.1 431PSL6252
431PSL/CSL6204 0.048 0.637 18.5 0.120 13.6 431PSL6254
431PSL/CSL6206 0.037 0.679 18.5 0.120 13.82 431PSL6256
431PSL/CSL6208 0.013 0.715 18.5 0.120 12.2 431PSL6258
432PSL6210 0.021 0.811 18.5 0.120 15.1 432PSL6260
432PSL6212 0.023 0.866 18.5 0.120 14.1 432PSL6262
433PSL6216 0.012 1.067 18.5 0.120 16.2 433PSL6266
433PSL6220 0.012 0.974 18.5 0.120 15.6 433PSL6270

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Ma
g
naPLUS / MARINER / Harsh Dut
y
Sin
g
le Phase Generator Specifications
MagnaPLUS
Model Main
Stator Main Rotor Exciter Stator Exciter Rotor
No Load
Excitation
240V / 60Hz
281PSL1500 4.200 0.400 18.0 0.120 11
281CSL1513 0.470 0.720 18.0 0.120 4.3
281PSL1511 1.420 0.381 18.0 0.120 8.3
281PSL1512 1.106 0.395 18.0 0.120 8.1
281PSL1513 0.632 0.430 18.0 0.120 8.7
282CSL1515 0.210 0.820 18.0 0.120 6.2
282PSL1714 0.190 0.350 18.0 0.120 13
282PSL1715 0.190 0.350 18.0 0.120 13
282PSL1716 0.110 0.360 18.0 0.120 12.4
283CSL1517 0.080 1.140 18.0 0.120 12.7
283PSL1717 0.500 0.410 18.0 0.120 11.8
283PSL1718 0.070 0.460 18.0 0.120 10.1
284CSL1518 0.060 1.410 18.0 0.120 12.5
284CSL1550 0.050 1.480 18.0 0.120 16
284PSL1750 0.050 0.550 18.0 0.120 11.1
285PSL1711 0.040 0.580 18.0 0.120 11
286PSL1712 0.030 0.710 18.0 0.120 9.7
287PSL1713 0.020 0.780 18.0 0.120 12.3
361PSL/CSL1611 0.070 0.750 23.0 0.135 17.5
361PSL/CSL1612 0.043 0.857 23.0 0.135 16.1
361PSL/CSL1613 0.037 0.926 23.0 0.135 13.6
362PSL/CSL1615 0.019 1.200 23.0 0.135 17
363PSL/CSL1617 0.012 1.350 23.0 0.135 23
431PSL6222 0.025 0.516 18.0 0.105 9.9
431PSL6224 0.013 0.615 18.0 0.105 13.8
431PSL6226 0.009 0.643 18.0 0.105 15.1
432PSL6228 0.007 0.852 18.0 0.105 11.2
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MagnaPLUS / MARINER / Harsh Duty
3 Phase 600V Generator Specifications
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4 Lead Main
Stator Main Rotor Exciter Stator Exciter Rotor
No Load
Excitation
600V / 60Hz 12 Lead 12 Lead
(Obsolete)
281PSL52463.20.43918.00.1209281PSL28102281PSL5261
282PSL52471.070.3418.00.12014.7282PSL28103282PSL5262
282PSL52481.070.3418.00.12014.7282PSL28104282PSL5263
282PSL52490.740.3718.00.12014.35282PSL28105282PSL5255
283PSL52500.450.418.00.12012.95283PSL28106283PSL5256
283PSL52510.390.4618.00.12011.2283PSL28107283PSL5257
284PSL52520.270.5218.00.12014.18284PSL28108284PSL5258
284PSL52530.220.5418.00.12014284PSL28109284PSL5264
285PSL52540.20.5818.00.12011.9285PSL28110285PSL5260
361PSL16320.3810.7523.50.12011.8361PSL36111361PSL3177
361PSL16330.2640.8123.50.12012.5361PSL36112361PSL3178
361PSL16340.1810.9923.50.12014.1361PSL36113361PSL1670
362PSL16350.1381.0523.50.12012.2362PSL36114362PSL1667
362PSL16360.0981.223.50.12010.8362PSL36115362PSL1668
363PSL16580.0691.3723.50.12012.2363PSL36116363PSL1666
431PSL62400.0210.81118.50.12015.1431PSL6610431PSL6508
431PSL62420.0370.67918.50.12013.82431PSL6611431PSL6509
431PSL62440.0130.71518.50.12012.2431PSL6612431PSL6505
432PSL42460.0230.86618.50.12014.1432PSL6613432PSL6506
433PSL62480.0120.97418.50.12015.6433PSL6614433PSL6507
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