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[Freddy W]

A Thought

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If the +ve or –ve from the Power Box is suspect, I could join them direct to the battery, bypassing the ammeter according to the wiring diagram.

This would prove if the original wiring was OK or not. Yes?

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Regards wet and bemused Fred

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PS its pouring down here in Gloucestershire.

[Frank]

If you did that and the battery then charged it would prove the fault to be the wiring from the power box through the ammeter to the battery. If the ammeter does show a discharge then it is likely to be the power box to ammeter side, I would have thought. Perhaps connections on the ammeter?.

[Thack]

Freddy W, could you clarify something? Going back to your original post: your original testing is a bit confusing. This bit: "...unplugged Powerbox, checked across the violet wires... checked DC voltage from power box". Just to be clear, did you unplug ALL the wires? Presumably not - the violet wires were still connected to the alternator otherwise you wouldn't see anything on the DC output from the powerbox. But then you say "Checked at the battery....", but does that mean you plugged the DC output wires back in first? It's important to understand EXACTLY what tests you did, but to summarise: is it true to say that the Powerbox output is 14V when not connected, and 12.4V when connected to the battery? If so, the next test is to see how much current is being drawn out of the Powerbox by unplugging the positive lead and inserting an ammeter into the circuit. If it's a lot, then something is drawing enough current to "pull down" the output voltage. Normally, of course, this would show up as a discharge on the ammeter, so I doubt that's the problem. Another essential test is to measure the output current from the alternator WHEN IT IS PLUGGED IN to the Powerbox and the Powerbox is plugged in to the battery (disconnect the positive lead and insert an ammeter in series). Finally, if the alternator is faulty, it could easily generate 30V under no load but collapse to a low voltage as soon as you try to draw any current from it. This is especially true if there is a high resistance connection somewhere the powerbox and the alternator windings. Personally, and in the absence of further information, my bet is on a problem with the alternator, or between the alternator and powerbox.

[Thack]

Oh, dammit! I put the same text in twice! Sorry, please ignore that post and read this, which is corrected............................. Freddy W, could you clarify something? Going back to your original post: your original testing is a bit confusing. This bit: "...unplugged Powerbox, checked across the violet wires... checked DC voltage from power box". Just to be clear, did you unplug ALL the wires? Presumably not - the violet wires were still connected to the alternator otherwise you wouldn't see anything on the DC output from the powerbox. But then you say "Checked at the battery....", but does that mean you plugged the DC output wires back in first? It's important to understand EXACTLY what tests you did, but to summarise: is it true to say that the Powerbox output is 14V when not connected, and 12.4V when connected to the battery? If so, the next test is to see how much current is being drawn out of the Powerbox by unplugging the positive lead and inserting an ammeter into the circuit. If it's a lot, then something is drawing enough current to "pull down" the output voltage. Normally, of course, this would show up as a discharge on the ammeter, so I doubt that's the problem. Another essential test is to measure the output VOLTAGE from the alternator WHEN IT IS PLUGGED IN to the Powerbox and the Powerbox is plugged in to the battery. If the alternator is faulty, it could easily generate 30V under no load but collapse to a low voltage as soon as you try to draw any current from it. This is especially true if there is a high resistance connection somewhere the powerbox and the alternator windings. Personally, and in the absence of further information, my bet is on a problem with the alternator, or between the alternator and powerbox.

[Norm]

Do as Frank said red from Powerbox to pos of battery and black to neg and test that.

[Gwilly]

Looking at it from my cosy chair just a few things spring to mind.

Do you believe what the ammeters telling you?
If yes then it shows current to be passing through it one direction only, i.e. battery to consumables, (negative discharge)

Yet Freddy says he has 14volts measured at the PB outlet terminal, Then as Frank mentions, this 14volts cannot be reaching the consumables side of the ammeter to redress the balance, reversing the flow if you like through the ammeter back into the battery. (positive charge).

So a fault in the harness wire PB to ammeter seems logical. Resistance ohms check of the disconnected cable may tell you something.

Or voltage drop test by using a needle inserted through the cable sheath and connected to measure volts DC at different locations upto the ammeter connection.

This would pinpoint the location of a break but my guess would be the connection where the original fitter joined the wire from the PB terminal to the harness...

[Norm]

Gwilly, this is where solder and heatshrink is your friend

[Freddy W]

Thank you Lads, one and all, for all your knowledgeable suggestions while sat in armchairs or having to wrap up warm in Oz whilst we are now sweltering in the summer sun.

In preparation for turning my loom into something approximating a Voodoo doll I took the primary case off to look at the beginning of the purple wires from the alternator
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Stone me!

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What did I see but where one wire was close to the spiky bit where the other one joined onto a coil, a small black smudge suspiciously like an electric burn. I pulled the two wires apart, started the engine and everything charged fine.

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So how to keep them apart and insulated? Does plastic metal conduct lecky or any other suggestions, my fingers are to stubby to wrap self amalgamating tape in such a small space.

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Anyway thanks all, I did try all the suggestion made above over a period of 3 days to no avail but it kept me out of trouble and got me deep into wiring diagrams.

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Regards Fred

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PS with the primary off noticed the clutch basket wasn't spinning square—but that could be another tale.

[Gwilly]

Well there you go, me talking tripe again. Glad you found it Fred.. Tricky stuff this lectric..

[Norm]

Freddy, can you put a piece of plastic between the 2 wires and put a small cable tie around the 2 wires and hold it all together, or if you can get some tape wrapped around it and then a cable tie to stop the tape from coming undone.