Massey 35. Advice needed please.

[Floordoor]

I’ll start by saying I’m not too mechanically minded but I’m not afraid to give things a go.

Our 35 stopped charging battery, was advised the Dynamo is probably done so I ordered a new one, read how to polarise a new dynamo thought how hard can it be!

Fitted the new one, disconnected battery leads, ran a wire from positive terminal to frame, ran a wire from negative terminal and brushed it over the bottom smaller connector on the dynamo a few times which made a blue spark.

Connected everything back up started her up but the amp meter is pointing to - instead of + and the dynamo is getting hot.

So that’s about the limit of my mechanical skills so hoping someone on here may be able to advise what I’ve done wrong or not done at all.

Thanks in advance.

 

[Mursal]

Dynamo charging circuit is extremely complicated, an alternator would have been an easier solution, but anyway.

So the tractor has the positive terminal on the battery connected to the frame, known as positive earth? Please double check this, first?

If the dynamo is new, you have two possible causes to it still not charging:
1 Regulator
2 Wiring

To get started:
If you disconnect the SMALL terminal on the dynamo (known as F).
With the tractor running connect a test wire from the negative on the battery (the one that goes to the large terminal on the starter) to the small terminal on the dynamo, it should start charging.
Please do not leave the test wire connected, just connect to watch the amp meter.

Always disconnect the battery (when unattended) until you get the problem sorted
See how you go .............

 

[REStracTORATION]

Sounds like you have polarised it the wrong way

Make sure the battery is negative earth.
As the new dynamos are neg earth,
So when it's running pull the little field wire off the dynamo get a wire from live terminal on starter and flash the field on dynamo untill blue spark that's it.
Should be ok now if it was ok before
Try this and report back before going down the control box route and wiring


Also was your old dynamo goosed
Did you test it
If you put a live and earth to it it should turn like an electric motor if it does your dynamo was ok and not the fault

Connections are the main reason this system packs up mainly bad earth's

 

[Mursal]

Just to help you @Floordoor the diagram shows the older positive earth connection. You can clearly see the larger positive terminal of the battery connected to the bodywork of the tractor. And the switch circuit connected to the smaller negative terminal.

On all modern vehicles its the negative that is connected to the steel body work and the positive will be connected to the switch circuit. This is known as Negative earth

Hope this helps ..............

 

[Floordoor]

So it is in fact negative earth and it seems I have polarised it the wrong way..... is it just a case of doing it the other way round? Please excuse the stupidity!

 

[Mursal]

That's a pity ...........
With the engine stopped, take a jumper lead from the positive on the battery and just tip it to the small F terminal on the dynamo. This will polarise the dynamo to negative earth. See if its now charging? If it is, the contacts in the regulator may be welded closed, you can check this by disconnecting the battery with the engine stopped, you may see a small spark/current flow as you disconnect? If so leave battery disconnected when unattended ...........

But if its not charging you probably popped the contacts in the regulator box (big shiny thing under the battery) with about 5 wires going to it. So new regulator will probably be required ..........

Take your time and please ask before connecting if unsure ...........

 

[Mursal]

Just for your information wiring diagram of a old 50 Massey charging will be identical on the 35.
Wire colours may vary

.

 

[Floordoor]

Do I leave both wires connected to the dynamo when running a lead from positive on battery to f terminal?

 

[Mursal]

Take the original wire off just to be on the safe side, that way you know the regulator is disconnected while you polarise the dynamo.

 

[Floordoor]

Tried this still no charge...is it looking like I’ve buggered the regulator?

 

[REStracTORATION]

Could of been the regulator to start with


Was the tractor positive earth before?

The regulators can give issues if it's a China one, the Lucas ones don't give to much issue normally
If the dynamo has been producing charge with now where to put it then it's possible the regulator is faulty.

 

[Mursal]

The dynamo is actually turning, sometimes they come with the pulley loose on the shaft?

You will have to get in at the regulator, not sure how much wire you have to play with?
Probably the most straight forward will be to visually check the wiring and if all looks good, replace the regulator.

Please make sure you now have the dynamo polarised negative earth (battery negative terminal connected to the steel bodywork) or the new regulator will fail as soon as you start the tractor. If unsure polarise again .............

A cheap regulator will be fine to get you up and going ............
Would this be your little darling?

Additional information you might find interesting
Terminal D goes to the large terminal on the dynamo labelled D
F goes to the little terminal on the dynamo labelled F
B goes to the positive battery (large terminal on the starter solenoid) terminal
E goes to the steel body work (eventually to the negative on the battery)