An electrical conundrum

Ouch! Could you fit one off a Jappa from the wreckers or would too many rivets be involved ;)
 
Dellortoman said:
Well, I figured out what's wrong with the Guzzi charging system. Voltage regulator is fucked. It's not switching the field coil on when the voltage drops.

Replacement is a bit expensive though. Here's one on ebay for $999  :o
http://www.ebay.com/itm/nEw-OEm-BOSCH-External-Voltage-Regulator-for-BMW-1967-to-1976-/280961959265
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I had similar problems with my Le Mans. Absolutely the reg was rubber ducked. Got it over to Mario at Thunderbikes. Good as new but the bastard wont tell me what he did. I have a suspicion it was just the earth but who knows  ::)
 
Hey Cam for the Guzzi reg try these guys they do a solid state jobbie for air heads and I reckon would work on your Guzzi.
http://www.motoelekt.com/charging.htm

With Tims issue interesting.. know I know you have checked the earth for the reg.. was that back to the battery ?
Also the supply to the regulator have you done a voltage drop test on it as you could be "seeing" battery voltage with the multi-meter but as the meter has like zero load it may be that when load is applied to the circuit ( by way of the reg ) that it up to the job. Is the ocnnector crimped ? and is there any signs for corrosion there. Or for that matter the field wires connectors at the reg.
 
Dellortoman said:
Did some grocery shopping while I was out.
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For a minute I thought my cold climate reds and my Tassie lobsters were on there way :D ...................... but, in your list of jobs you didn't mention going to the Post Office. :(
 
Guzzi now fixed. Went and bought a solid state voltage regulator as Brett suggested. It's the same reg as used on a bunch of old European cars (VW, Mercedes, etc.) so Ashdown and Ingram had one on the shelf. Even had the same terminal pin pattern so the 3-pin connector plugged straight on.

However, Tim's 3C is still confounding me.  I inserted an ammeter in one of the phase wires coming out of the alternator, put it on 10A AC scale and started the engine. Zero amps. Tried the other phase wires, same result. I'd have thought even a fucked alternator would give a fraction of an amp, but the reading was 0.00 on all phases. I thought the amp scale on my multi-meter might have been rooted (blown fuse?) so I grabbed another meter, same reading. I opened up both multimeters and checked their fuses just to be sure. Also tried one on a DC circuit and got a reading on the 10 A scale, so the ammeter is working.

Anyway, it seems the root of the problem may be the alternator not doing anything. Although I still have my doubts. Why would two independent phase coils both be knackered? It's also strange that it makes some AC volts but no amps. I've got another stator plate so I'll try the charging coils off that and see what happens. But it's knock-off time, and getting too bloody hot in the shed now anyway, so I'll call it quits for today. Is that OK with you Davo?
 
At the risk of proving how stupid I am, isn't an alternator a copper coil moving around a magnet. How's the magnet?
Don't they reverse polarity on occasion as well. Or am I not getting this?
 
Dellortoman said:
Guzzi now fixed. Went and bought a solid state voltage regulator as Brett suggested. It's the same reg as used on a bunch of old European cars (VW, Mercedes, etc.) so Ashdown and Ingram had one on the shelf. Even had the same terminal pin pattern so the 3-pin connector plugged straight on.

However, Tim's 3C is still confounding me.  I inserted an ammeter in one of the phase wires coming out of the alternator, put it on 10A AC scale and started the engine. Zero amps. Tried the other phase wires, same result. I'd have thought even a fucked alternator would give a fraction of an amp, but the reading was 0.00 on all phases. I thought the amp scale on my multi-meter might have been rooted (blown fuse?) so I grabbed another meter, same reading. I opened up both multimeters and checked their fuses just to be sure. Also tried one on a DC circuit and got a reading on the 10 A scale, so the ammeter is working.

Anyway, it seems the root of the problem may be the alternator not doing anything. Although I still have my doubts. Why would two independent phase coils both be knackered? It's also strange that it makes some AC volts but no amps. I've got another stator plate so I'll try the charging coils off that and see what happens. But it's knock-off time, and getting too bloody hot in the shed now anyway, so I'll call it quits for today. Is that OK with you Davo?
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Yeah mate. Crickets on the telly and I know how much you love a one dayer.
 
Dellortoman said:
Anyway, it seems the root of the problem may be the alternator not doing anything. Although I still have my doubts. Why would two independent phase coils both be knackered? It's also strange that it makes some AC volts but no amps.
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I'm pretty sure amps are 'drawn' (i.e. work done) rather than simply measured as if they were hiding down a hole. Stick a 20 ohm resistor in the line and you should measure about 1.5 amps...
 
Hi Andy. Either you're not making sense, or I don't follow what you're trying to say. 

I can't see a resistor in the line making any difference. There's already a resistive circuit in the RR.  All I did was break a phase wire and re-connect it via an ammeter.  If I'd had a clamp-type ammeter, I wouldn't even have needed to break the wire - just put the clamp around it.

The way I understand it is the RR takes the full AC output of the alternator and rectifies it into DC (that's the rectifier bit). The regulator part of the RR looks at system voltage and works out how much current needs to be fed into the system to maintain a set voltage (around 14V I guess). Any surplus is simply shunted to earth. The energy of the current fed into the bike's system feeds the various appliances such as ignition, lights and battery charging. The energy of the earth shunt current being dissipated via a resistive circuit in the regulator, which gets hot. That's why shunt regulators need cooling fins.

So it doesn't matter what the 12V system voltage happens to be, the alternator should always be shoving full current  through the RR. That was what I was expecting to measure. But I got zero.
 
Coming in a bit late to this one, but Cam I think Andy is on track. There won?t be any measured amps without a load. If the reg took all the amps that the alternator could produce all the time, the alternator would be under full load at all times and quickly be rooted, as would the reg, and the engine under very heavy load to drive it.
From my experience when checking ac volts between phases on an alternator there is usually over 100 between any two wires. Even my 6V Ducati single had 85, which meant I could just stick a 12v reg on, converted.
What is at the root of your problem is certainly a conundrum.
 
All the R/R does is grounding both ends of the alternator coil once the voltage on DC side hits the preset limit. However, with the engine running, some current will flow for the ignition and battery recharge on the AC side, even with no other load added like headlights or so. You should be able to measure it, but better watch out to have set your multimeter to Amps AC range, in DC range it will show zero all the time. ;)

If there are no signs of blueish/burned or otherwise damaged coils visible, my bet would be on the wiring of the alternator coils. These wiring damages can play out to come into effect only when engine is running, at engine stillstand everything measures up nicely. I think the most critical spot is where the wires are running through the engine casing. Had such damage once on another bike, it took me 2 weeks to locate it. :D Needless to say this happened while travelling Italy, far away from home, and the bike drove me nearly nuts with its erratic charging circuit issues. :-X
 
The way I understand it the alternator will only "shove full current through the RR" if there is something drawing that current - i.e. some sort of load.

Or to put it another way that full current might be tiny if there's no load, or much bigger if there's lots of load...

Thing is, there must be some sort of load when you have the bike running (even if it's tiny) but to force the issue, just switch the headlight on.

But I'm probably not understanding it either!

Oops, hadn't seen the previous posts, sorry - all saying the same thing!

--
Dick
 
Well, it appears that neither of my multimeters works on the AC amps range. I disconnected all 4 phase wires (2 pairs) coming from the alternator and connected one pair directly to a headlight globe. Started the engine and the globe lit up. It got brighter as I revved the engine as expected. I connected a multimeter in series with it (10A AC scale) and it read zero. The globe was lit so there was definitely a current flowing - about 3 amps according to my calculations. Tried the other alternator coil with same result, so the alternator is actually working.

Interestingly, the alternator voltage peaked at around 12V RMS when powering the headlight. Kinda makes you wonder whether a voltage regulator is necessary. The early bikes with only one alternator coil didn't have them.

Anyway, back to the head scratching. Looking again at the RR. Not sure how to test it without a variable voltage AC power supply.

 
SimonR501 said:
That is great news Cam, but ever the one to think too deeply I would be concerned at wtf it was? Loose connection if nothing changed?
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That would be my guess as well.
Cam I know you would have but did you check to make sure that the connector to + supply for the reg is good as its usually something so bloody simple it stares you in the eye.............how do I know, dont ask me what the issue was with the intermittant miss on the RGS will ya.  I can hear Mark's favourite saying as I type. something to do with the cry of a crow and the type of motor cycles we choose to own and occasionally ride.
Well done on sorting the Guzzi, say you, Marty and Maurice could form a sub club... I will wait till a while longer before I entertain a Guzzi.
 
Yes Brett, had a similar thing with my dishwasher!

Pressed the 'ON' button one day and nothing!!!!! I checked the supplies, but all in order.
I asked an electrician at work who laconically stated that it was a bad connection - probably in the plug. Took the plug apart, all looked good and solid - nothing loose, burnt or corroded.
Cleaned up the wires (snipped off and re-made) and everything worked fine for years.
 
Yeah, that's the kind of thing I was thinking, but we checked all connections when the problem first appeared. Maybe it was more than one connection, crap on the fuse holder, who knows? I'd have thought that all the dismantling and reassembling, trialling different RRs, replacing the fuse, etc. would have revealed a loose connection sooner than this.

I'm wondering if it's possible to have an intermittent fault in the RR. Sometimes it works, sometimes it doesn't sort of thing. I'm aware that electronic circuits can sometimes have faults that are temperature dependent. I'll suggest to Tim that he keep an eye on it. Maybe tape a cheapo voltmeter to the tank for a while (I have a few $5 multimeters lying around). It's a pity the charge light doesn't work on these old Laverdas.

PS: Why is the opposite of dismantling not "mantling"?
 
There are battery condition gauges on ebay for less than $10, made you know where. Who knows how long they might last but seeing 14 on the dash would be nice
 
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