Pickup ID

[godathunder]

Ive finally got round to cutting a proper bridge for my Shergold project

( https://www.basschat.co.uk/topic/483271-shergold-electric-upright/ )

and excitedly mounted the pickups only to find that silence ensues

 

I assumed that theyre piezos so was expecting a pretty low output but this is zero output. 

Perhaps Im mistaken about them being piezos and they require a polarising voltage.

The jack socket has a 4700pF capacitor wired in parallel across the terminals (Im assuming its for hf rolloff). Ive removed it but theres still no output.

Theyre approx 27mm long and are made of a blue plastic inner with brass/copper folded around. Theyre from the 20th century

Does anyone have any idea what the mystery pickups may be?

 

[NickA]

Piezo for sure.  Usually a connection between the piezo element and the cabling has gone open circuit.  Very hard or impossible to fix sadly.

 

I had a shadow one ( similar) go down that way, separated the two halves and found one side was ok and still useable.

[godathunder]

yeah, that was my feeling but I was just holding out a faint glimmer of hope that someone would identify them as some esoteric non piezo that needed some dc applied.

 

Ah well, time to break out the soldering iron and magnifying glass

[godathunder]

The soldering iron and magnifying glass payed dividends. Both of the solder joints to the piezo wafer had failed on the 1st pickup in line. It took a few tries to get a decent connection but I got it working. Predictably, after reassembling it,the joints pretty much immediately failed again so this time a cut down a piece of microbore pipe with a dremel type tool and reshaped it to form some strain relief.Lashings of epoxy completed its quest for solidity. Despite this, the connection to the 2nd pickup is intermittent. At some future point I'll make a joint in the cable instead. The jury is out on the sound at the moment, it seems a bit boomy and undefined but the preamp Im using isnt really suited. I'll continue this exciting story in the original thread

https://www.basschat.co.uk/topic/483271-shergold-electric-upright/