Regulator Confusion

[keithtraffic]

I have had some charging problems (which I won't go into here) but was reading the Workshop Manual about the charging system and specifically how the regulator works. However, given the circuit diagram I cannot see how it can possibly work as described.

I felt sure I had seem a full description of the operation on the forum somewhere (and it was slightly different to the workshop manual), but despite several searches I can't seem to locate it now.

Does anyone know if there is one and could they point me at it please.

[AshimotoK0]

Been meaning to put this on here for a bit .... here goes 

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[Oggie400F]

Great info Ash
Is this going into Aladdin’s Cave if it’s not already?

[AshimotoK0]

Great info Ash
Is this going into Aladdin’s Cave if it’s not already?

Yes will do it now .

[keithtraffic]

Thanks Ash - this description confirms what I had deduced and found from testing the regulator with an accurate power supply and is definitely different from what is described in the Workshop Manual . The really subtle point is that in Mode 2 the relay armature is in the middle of the two contacts and it is that which selects the higher resistance to the Field coil - this is completely missed in the manual!

But I still can't see the logic, in Mode 3, of the regulator sticking the 10ohm resistor straight across the battery - apart from being rather wasteful the resistor gets incredibly hot as its dissipating nearly 20W - and there's plenty of other load to discharge the battery to bring its voltage back down a bit.

From a purely Engineering standpoint the design does seem rather flaky - simply relying on the regulator armature just sitting in the middle position to optimally regulate the battery charging but I guess its relatively simple and low cost.

Has anyone come up with an electronic version that mimics the regulator operation, giving proper control of the Field current - it seems to be a simple thing to do with a couple of FETs and a dual op-amp and it would be highly accurate!

[AshimotoK0]

I think that circuit needs to disipate the current because you need current through the relay coil to keep it closed during the high voltage condition. I agree it's rather a crude regulator design and in 1968 Honda were aready using solid state devices (e.g thyristors and zener diodes) in a circuit to regulate by current dumping, on their single phase alternators. In reality though I have owned 4  400/4's one of which I did over 20k miles on and never had a problem with the electromechanical regulators on any of them.  It would be interesting to see what other members experiences are ..particuarly my friend who is a member and his sandcast has done well over 100k miles.  Yes the resistors will get hot but they are ceramic tube wirewound  types, externally mounted, and I have never heard of one burning out. It's kind of neat to create a voltage regulator with basically two resistors and a relay plus the non-slip ring alternator design is a brilliant  IMHO for a bike designed over 50 yeras ago..

I think the combined regulator/regulators avialable for our SOHC fours use a solid state circuit to perform the same function as the mechanical regulator.

I suppose the mechanical regulator is a bit like the ignition points .. on paper  a rather crude design but points too are generally very reliable if you use decent quality ones like the original ones Honda fitted. I can't imagine the ignition system DS sells, which has the electronics mounted on a PCB in the points and not potted, lasting for 50 years plus.

[Bryanj]

Back in the 70's I had my first 500 and occasionally the regulator would "stick" in low charge mode, you could tell at night as the lights would dim. usually going over a bump, none of those on our roads of course, started it working again and I never changed it.

You can fit the DOHC reg/rec to the SOHC I have a wiring diagram somewhere and Steve had a 500 with Yamaha wheels and a home built regulator for which somewhere I have a circuit diagram