Regulator/rectifier FOAK
in [UK Motorcycles]
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From: Simon Wilson on 19 Sep 2006 16:19 Mark Olson wrote: > Simon Wilson <siwilson(a)nospam.hotmail.com> wrote: > > John wrote: > > > > <snip> > > > > > > If you have 12v across the rotor field coil then you should have > > > full output from the stator. Either the stator is knackered or the > > > rectifyer isn't allowing the current to pass to the battery. The > > > only way you can tell is to use a multi-meter to check the stator > > > ouput while you have a 12 v feed to the rotor. There are three > > > wires from the stator. Set m/m to AC ~ volts. You should get > > > about 6-8vAC across any two stator wires, and it should increase > > > as you rev engine. > > > > > > John > > > > Thanks for that advice, why didn't I check this before? aaarrrggh. > > > > With new battery + correctly wired (new) reg/rec, I rode 100 miles > > down the M4[1] with the lights on, all seemed ok, until I turned > > off the motorway and stopped to read the map. Within a minute or > > two the ABS light started flashing again. (Symptom of low batt. > > volts.) So, my theories so far have all been wrong. > > > > I had previously checked all of the stator coil resistances and for > > shorts to earth. > > > > I measured the ac voltages. Between each pair of wires I get 7.8V > > ac, rising to about 14V ac as the revs rise. But, between one pair, > > there is just 2V ac, all of the time (doesn't rise). So, is my > > stator kaput? > > If possible, measure the AC voltage open-circuit, not with the > reg-rect attached to the stator (but with 12V across the field > winding). Measuring with the rectifier attached can be inconclusive, > a fault in the stator or in the diode stack can cause similar > readings. > > Measuring open circuit stator voltages between any two phases you > should see... oh, perhaps 70VAC? Whatever it is, it should be the > same for all three combinations of leads. If one pair is markedly > different from the other two, your stator's toast. > > > 180 quid for a rewind, vs. about 220 for a new one, vs. about > > 400-500 quid for the 40A alternator which is by all accounts much > > more reliable. (The original owner had already replaced the > > alternator once, though I suspect wiring the new one up fully > > fielded shortened its life?) > > What's brown and sounds like a bell. > > I would guess that you haven't found the proper alternator rewinders, > 180 quid seems way over the top for rewinding what is essentially a > normal (albeit small) auto alternator. I'd seek out an auto electrics > shop rather than a bike oriented shop... Ok I will try measure AC open circuit tomorrow, though I am expecting the worst since it is a brand new reg/rec don't forget. If anyone has any recommendations for rewinders, please post. Thanks -- /Simon
From: Simon Wilson on 26 Sep 2006 10:15
Mark Olson wrote: > Simon Wilson <siwilson(a)nospam.hotmail.com> wrote: > > John wrote: > > > > <snip> > > > > > > If you have 12v across the rotor field coil then you should have > > > full output from the stator. Either the stator is knackered or the > > > rectifyer isn't allowing the current to pass to the battery. The > > > only way you can tell is to use a multi-meter to check the stator > > > ouput while you have a 12 v feed to the rotor. There are three > > > wires from the stator. Set m/m to AC ~ volts. You should get > > > about 6-8vAC across any two stator wires, and it should increase > > > as you rev engine. > > > > > > John > > > > Thanks for that advice, why didn't I check this before? aaarrrggh. > > > > With new battery + correctly wired (new) reg/rec, I rode 100 miles > > down the M4[1] with the lights on, all seemed ok, until I turned > > off the motorway and stopped to read the map. Within a minute or > > two the ABS light started flashing again. (Symptom of low batt. > > volts.) So, my theories so far have all been wrong. > > > > I had previously checked all of the stator coil resistances and for > > shorts to earth. > > > > I measured the ac voltages. Between each pair of wires I get 7.8V > > ac, rising to about 14V ac as the revs rise. But, between one pair, > > there is just 2V ac, all of the time (doesn't rise). So, is my > > stator kaput? > > If possible, measure the AC voltage open-circuit, not with the > reg-rect attached to the stator (but with 12V across the field > winding). Measuring with the rectifier attached can be inconclusive, > a fault in the stator or in the diode stack can cause similar > readings. > > Measuring open circuit stator voltages between any two phases you > should see... oh, perhaps 70VAC? Whatever it is, it should be the > same for all three combinations of leads. If one pair is markedly > different from the other two, your stator's toast. > > > 180 quid for a rewind, vs. about 220 for a new one, vs. about > > 400-500 quid for the 40A alternator which is by all accounts much > > more reliable. (The original owner had already replaced the > > alternator once, though I suspect wiring the new one up fully > > fielded shortened its life?) > > What's brown and sounds like a bell. > > I would guess that you haven't found the proper alternator rewinders, > 180 quid seems way over the top for rewinding what is essentially a > normal (albeit small) auto alternator. I'd seek out an auto electrics > shop rather than a bike oriented shop... Ok the stator's toast. On open circuit, only a couple of volts across one pair of wires - the other pairs are ok. I managed to get a used 40A alternator on ebay, a bit pricey, but still less than a new one. So that's the next job. Anyone need a reg/rec, 'cos now I have two spare ones? -- /Simon |