Frankensteining a working pickup

 

Problem: we have a hexaphonic pickup with one or more elements that are no longer working.


After establishing that the ribbon was not functioning properly, the potting wax was removed in order to execute a ribbon repair/replacement as per Wayne Joness’ excellent GR300 site (complete info at

http://www.joness.com/gr300/r_pickup_repair.htm). It was at this point that I established that one of the elements was in fact no longer working.


Solution: replace the non-functioning element by grafting a working element from another pickup.


(This is the second pickup that I’ve been able to resurrect.)


In this case, the sixth element is testing as non-functional, and I had the remains of another pickup where the #6 element still tested as good.....

The first touchy thing to do was to remove the elements from the outer shell. By slowly and carefully drawing a utility knife along the seams, I was able to loosen the elements from the shell.

Now the fun part - the hex pickup is really six miniature humbucking pickups, connected by a ribbon that consolidates all the connections. Working with a pickup that was essentially dead anyways, I discovered that I could cut an individual pickup segment from the rest and have it test as still usable...

I had to be careful to not crack or break the outer shell with too much pressure from insertion or twisting of the blade. The hardest part was loosening the glue at the short ends of the elements, inside the casing.

I made both cuts a little ‘proud’ of the where they should have been to allow myself material to adjust the fit and alignment inside the shell, both of which I adjusted with the side of the cutoff wheel. It is a little hard to see in the pic, but the seam is there.

So,...

Once back to the solder bench, I re-confirmed that all elements were testing as good. I then glued the donor element to the rest with some crazy glue, and used a drop of glue on each end of the element stack to secure it to the shell. I then soldered a ribbon cable to each element, duplicating the ground connection to the donor element (I went with the ribbon so that I’d have a single cable going to the flat ribbon that would connect to the GR electronics card).

One thing that I didn’t get a picture of is the remains of the original ribbon where it is connected to all the elements. It’s wider than the elements themselves, and so was folded up when the elements were glued into the shell (you can see it a little in the pic above, and a remnant in the pic below). Some of this was torn off when I separated the elements from the shell, but the remainder has to be carefully cut off, otherwise there could be shorts between elements, causing intermittent or false continuity between elements and/or ground (this caused me to have to do a little troubleshooting on this pickup as this caused a bit of an isolation problem between two strings until I figured this out).

So, to clean everything up, I covered the back with black gaffer’s tape, as well as wrapping the solder connections to the Roland ribbon.

And here’s a last test, plugged into an STK-1 board (the board’s set up for a wide pickup though). 

...it’s alive, it’s ALIVE, IT’S ALIVE!!!