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This is just a quick 'sidebar' to Alex's "Rich running" thread . It's fairly esoteric info; but just in case someone is interested, here's a photo of what is inside a Ducati Elettrotecnica pick-up.

On the left, the pulse coil and its laminated iron core; on the right, in the packet, you can see a resistor/diode (sorry, can't remember now which). In this instance, it was this that had failed.

Thank you for this information. Seems that there are 2 components visible - a resistor and a split diode, with one half rotated upside down. Right?
My measurements on a pickup showed that in fact ther must be a diode in series with the coil. It's not clear how the resistor was connected to the coil, and which value it has. Is it possible for you to measure it?

Hans

More information is always good,looks like they could be repairable if the potting can be removed.
Thanks for posting.

Regards,
Alex

Hi Hans,

From the info I kept at the time, the resistor value was 335 ohms. Unfortunately, I can't say how it was connected to the coil. The technician at West Country Windings who pulled the pick-up apart had already finished the job when I went in to see him, and I didn't think to ask. Sorry.

And thanks for identifying the other bits as a diode. I thought the pick-up had had both, but I couldn't remember, to be honest. And I'm not competent to identify those broken pieces as a diode!

Ciao

Craig

Scottish888 wrote:<snip> ... looks like they could be repairable if the potting can be removed.

Hi Alex,

Well, everything is repairable of course, even when not designed to be - just depends on at what price . Also, I was lucky enuf to find someone at West Country Windings who had the interest to find out what had failed - and then the competence to fix it.

The most difficult bit, as you suggest, was removing the epoxy. A mixture of physical assault, solvent and obstinate determination got there, but that diode suffered in the fight.

The replacement for the resistor that had failed cost, literally, 10p. The labour was a little more . But the rebuilt pick-up is still working, 20 years on.

Ventodue wrote:Hi Hans,

From the info I kept at the time, the resistor value was 335 ohms. Unfortunately, I can't say how it was connected to the coil. The technician at West Country Windings who pulled the pick-up apart had already finished the job when I went in to see him, and I didn't think to ask. Sorry.

And thanks for identifying the other bits as a diode. I thought the pick-up had had both, but I couldn't remember, to be honest. And I'm not competent to identify those broken pieces as a diode!

Ciao

Craig

Craig,

I did not identify the two pieces as a diode solely by their appearance, but indirectly by my measurements made with my spare pickup (as posted elsewhwere). These showed the characteristics of a diode connected in series with the coil - letting pass current in one direction while blocking it in the other. The resistor was in fact identified by his shape and apperance. Still unclear is, if the resistor is connected in series or in parallel with the coil.

Hans