Emmons M5189 Humbucker wiring

[Richard Case]

The guitar I'm working on has an Emmons Pentad pickup installed (two M5189 hum bucking, among other things).

My issue is I'm experiencing more hum from the pickup than I would expect, in all 5 positions.

My question is: does the braided shielding covering the 4 pickup wires ground the pickup via the baseplate?

This is what a new pickup looks like, with the shielding (courtesy of this post https://bb.steelguitarforum.com/viewtop ... 10d14de9f9)



And this is my pickup (sorry, haven't got a better pic handy) - I peeled back the insulation tape the previous owner installed, hence the residue:



Running a separate wire grounding the baseplate did not seem to make much difference.

Next step would probably be verifying the circuit in the 5-way switch, thought I'd ask here first though before doing so



Thanks!

[Scott Swartz]

I would suggest removing the switch from the circuit and seeing if you can get it working properly as a normally wired series humbucker. I only see 2 wires leaving each bobbin which would be the finishes and starts of each coil.

If the coils are wound the same direction for humbucking you connect the finishes together, it they are wound opposite the finish of the first coil connects to the start of the second coil. The wires not connected become the hot and ground of the pickup. The common way is the coils are wound the same direction.

Obviously the wires are not marked start and finish so you have to figure it out. The red and green are one of the coils, and the black white the other. You could begin by assuming the green wire is a start which would make the red a finish. From there, try the white connecting to the red. If it does not hum cancel try connecting the black to the red. If your assumption about green being the start is wrong the process will still work.

If neither way hum cancels there could be an issue with one of the coils. Do they measure out close in resistance?

The hum cancelling effect is independent of the magnetics so even if there is an issue with the magnets (unlikely but possible) that will only affect the audio signal created by the moving string.

I have not seen the original Pentad schematic but it may be out there somewhere.

[Richard Case]

Thanks Scott. I found a faulty joint and repaired it. This along with the ground wire seems to have sorted the problem out to some extent.

I will retest once the guitar is fully setup, and if things still seem a bit dodgy first thing I will do is test it direct, without the switch in the circuit.

[Chris Lucker]

I do not know if this wiring diagram for Emmons Dual Coils is the same as for an Emmons Pentads, but this is what Ron Sr sent me years ago:

[Richard Case]

Thanks Chris. Lynn Stafford was kind of enough to provide me with this official wiring diagram.