Charging voltage too high?

[barryh]

That looks like a good match and and an excellent price.

I might even buy one !

http://www.vehicleelectricsshop.co.uk/p ... VOLVO.html

[SteveD]

Bosch RE57 from your local auto shop does the job. It might be cheaper and more widely available.

Does a re57 suit the older bikes like /6

re57 has 3 pins and I think a 74 has two pins?
I might be dreaming.

The RE55 then? It has 2 pins.

[Hoof]

VERG1058 EXTERNAL VOLTAGE REGULATOR BOSCH VALEO 12V VOLT BMW - solid state

Arrived this morning - it's about half the size and half the weight of the original yellow taped mechanical regulator but the fixing holes are in the same place and the 3 pin connection is the same. Seems a good solid unit
Box and regulator are marked HC CARGO 130675 VR-B191
I'll put it on later and see if the problem is solved or I just have another item for the spares box (as when I disassembled the old mechanical regulator it appeared to be OK).

[Hoof]

Now fitted the new voltage regulator and still too many volts! - up to 18 volts at 3,000 revs.....so time to think again!
Any suggestions most welcome...

[SteveD]

What are you using to measure the voltage and where are you measuring the voltage?

[Hoof]

I am using a voltmeter at the battery....The voltmeter on the Bike is reading over the top of the scale!

[barryh]

Now fitted the new voltage regulator and still too many volts! - up to 18 volts at 3,000 revs.....so time to think again!
Any suggestions most welcome...

This sounds like it might be a wiring fault. If the the current to the rotor is interrupted, which is what the regulator does just very fast, then the charging voltage has to drop. The regulator can be thought of as a device that senses the voltage on D+ and operates a simple switch between D- and DF so as a test if either D- or DF are disconnected the voltage should drop.

[Hoof]

I struggle with this and think very slowly .... :- The Voltage is not regulated properly (as it is too high) , so the regulator (which is new and not faulty) is nevertheless not regulating so it must be a wiring fault? - as I have checked the brown wire (D-) to negative earth it is the DF or D+ connection at fault and that is what I should check next? ie I need to check all the Df and D+ connections from the alternator via the rectifier and the Regulator to the battery.

I must sound as if I am in pain!

[barryh]

By wiring fault I was thinking it might not be wired as shown in the diagram. Not sure how that could happen but what else is there ? If breaking the current through the rotor caused the voltage to fall at least it would demonstrate the expected normal response. Where to break the circuit ? I think I would be tempted to pull off the DF spade connector at the brush holder. That way you would be absolutely certain there was no current flowing through the rotor.

If the voltage falls to 12 volts and I don't see how it couldn't, I would then trace the DF wire back to the regulator.
The symptoms you are observing suggest there is a permanent system voltage on that DF wire. That could be because the regulator was faulty or it could be a wiring fault that placed a permanent live feed on that wire, One possibility would be the D+ and DF wires got crossed. Hard to see how that could happen with the type of connector employed but with weird problems like this you have to assume nothing and apply a rigid logical fault finding approach.

[jagarra]

Can you check the condition of the D + wire between the diode board and the regulator, to see if the insulation is cracked.