Dynamo problems

[alcmk2]

red charge light stays on even when driving at 30 mph, but not every time glows very bright on tick over and will not go out.
the car has an automatic belt tensioner, do these work? orshould you stil tighten the fan belt.
Does this point to new brushes required or a voltage box problem. I do not own a multi tester so I am unable to do any detailed tests (so many on the market which one do you buy)

[piman]

Hello Alc,

the first check would be the brushes, both for length and that they are not stuck in the brush holder.
If there is reasonable tension on the drive belt then the tensioner is probably OK.

Alec

[PJF]

I agree with piman that belt tension and brushes are the first things to consider.

However, since the Regulator and Dynamo work in concert, failure in one component may be masked by the other.

The RB340 is a pretty reliable component but if there is one weakness, it is the Current Regulator contact, which does the bulk of the ‘Regulation’.

It oscillates, causing sparking which, over time, can result in poor contact.

For those not well versed in ‘electrics’, I would urge the use of an auto-electrician. However, there is one thing you can try to see whether the regulator is at fault.

That is to raise the tick-over rate to say 1000 rpm and to connect the ‘F’ terminal to the ‘D’ terminal (at low revs, they should be connected giving the highest possible field current).

This could be achived by carefully bridging the ‘WL’ and ‘F’ terminals with a small screwdriver (the WL and D terminals are connected and have Brown/Yellow and Brown/Green leads attached respectively).

If the Ignition Warning lamp dims appreciably then it suggests that the Voltage or Current Regulator contacts may be oxidised or worn.

The contacts can be ‘dressed’ with a diamond spatula but it may then require that the Regulator is re-adjusted.

I have placed an RB340 page here

[alcmk2]

Many thanks for the suggestions, I will try them this week and report back with my results. This could prove useful for someone else. Thanks again.

Best Wishes
Alan

[piman]

Hello Alc,

in response to the last part of your query. If you want to buy a multimeter, it's very much up to what you want to spend but a basic hobby meter can be bought fairly cheaply. The most important thing is to learn a few basic rules on how to carry out tests.

E.g., there was a method of checking the voltage to a coil in the JEC magazine a couple of issues ago which suggested disconnecting the live feed to the coil to check if it is receiving full voltage, i.e checking for poor contacts in the ignition switch and loom. Unless current is flowing in the circuit, that result will always be full voltage no matter how high a resistance is in circuit. It is only when the circuit is loaded will a volts drop across a poor connection shows up.

Alec

[alcmk2]

When I took the dynamo off with the power steering pump, I detached the pump and inside there was covering of red dust. So I thought that instead of replacing just the brushes,let's push the boat out and replace the dynamo.
After two days of BST(blood sweat&tears) the situation is that the ignition warning light is still doing the same as before,although when I first started up the light went out and the ammeter showed a nice healthy charge, but after driving for about five minutes things reverted to the previous situation plus the steering has got heavy
A depressing situation for an amateur mechanic

[alcmk2]

Hello Dear Readers
Well things have changed after thinking that the voltage regulator was at fault I noticed at tick over the dynamo pulley was not moving a loose belt maybe, so I adjusted the belt up and turned on the engine. At tickover with the wheels straight ahead all was well, but as soon as I turned the steering wheel on came the red light and the pulley wheel for the dynamo stopped. So it would seem that the coupling from dynamo to PAS pump was not alighned properly, but I made sure that the pump seated properly before tightening down of the threee bolts.
Off it comes tomorrow

[piman]

Hello Alc,

that is a new one?

Could there be a problem with your power steering pump, i.e. seized? (I must admit to having no experience of power steering as I avoid cars that have them fitted.)
I don't know that misalignment would cause the effect you describe.

Alec

[alcmk2]

Well now that the dust has settled the drive on both of the dynamos is different, with the old measuring 10mm and the replacement being 5mm I have taken photos and e-mailed David Manners although their e-mail does not appear to have the facility to attach photos. Let's what that brings

[piman]

Hello Alc,

when you say the drive, are you measuring the pulley groove width, if so where, as 5 mm is very narrow?

Alec

[PJF]

For those who may be following this thread, here are some pics that Alan sent me:
HERE

[alcmk2]

Many thanks to webman for producing he photos, as you can see there is a marked difference between the two PAS drives that mate with the pump.After speaking with David Manners today, my only option is to send them both dynamos and they will refurbish my old one as there are none available to swap with. It's interesting (or maybe not!) to realise that a simple unbolt one and bolt on another developes into something like this. You don't get this in your Haynes manual.

Regards for now

Alan