Hi, my massey 1976 135 uk model is destroying dynamo's, it has had 4 dynamo's and regulators in the last 18 month, it has recently had a new wiring harness and battery, a few people have said check the oil pressure switch on the gauge but it has the old mechanical type gauge fitted, i have noticed the fuel gauge will only work with 1/4 throttle and upwards, when tractor was charging it was putting out 14 volts at 1/2 throttle, any ideas why they keep failing?, thanks, Steve
dynamo deaths
- Thread starter stevemf20
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Redneck in training
Elite Member
I am not familiar with MF but are you sure it has a dynamo. I would think that it has an alternator. What exactly is failing such as bearings failure, winding or exciter burns etc. Is the tractor gas or diesel?
Hi, it has a Perkins diesel, definately dynamo, i'm not exactly sure what is happening to the dynamos (not bearing failure), i tested the dynamo and there was only 0.6 of a volt at 1/2 throttle, all dynamos have been polarized before use, i stripped the dynamo today just out of interest and found that there was no magnetism in it (should there be)?, is the cut off controlled by ignition switch?, any ideas?, thanks.
Redneck in training
Elite Member
If there isn't obvious damage to the dynamo such as burned commutator or winding then my guess is the most likely culprit is the regulator.
I have seen dynamo last time about 30 years ago and only vaguely remember setting the voltage and overcurrent protection by adjusting the relays.
The regulator has to supply current to the excitation winding (stator) to create magnetic field. The DC current is taken from the rotor where it is rectified by the commutator. There should be two wires one small to the excitation and the bigger is the 12V to the battery. Sometimes there is also ground wire. Check all the connections. Specifically the connection to the ground and minus of the battery and regulator. To check the wires is obvious but the ground is often the problem.
You should also post in the general maintenance/repair forum.
banjodunn
Veteran Member
G'day and welcome to TBN it is possible you have a bad reg ditch the lot and put an alternator on it an easy fit and better charging system check out the bare co site for a kit.
Jon
Jon
