Distillate Hum/potential grounding issue

[Khrist92]

For a little while now I have noticed the hum (see below link for sample) on my Distillate and was wondering if was a grounding issue or something else.

https://drive.google.com/open?id=1XzUQf1-V_egeg-ws0xE_ONSnKrWNSWTE

The first part of the sample is played without touching either the switches, back coverplate, computer interface (it was recorded direct) or the metal parts of the 1/4" instrumental cable. The second part is played while I am touching the metal end of the instrument cable; as you can hear it is completely absent.

Below I have attached a few high-res photos of the electronics cavity.

Prior to this I made sure to replace with a new battery and test it through different amps, interfaces and etc.; though the building I live and practice in are both quite old.

Thank you, and I hope everyone is doing ok in this age of self-isolation.

[pauldo]

Sounds like, a grounding issue if it changes when you touch the metal part of the cable.

Disclaimer: electrical stuff is magic to me.  There are smarter people who can and will assist you with troubleshooting techniques I the near future.

Good luck.

[FC Bass]

Could be poor contact between one of the switches/pots and the Silver paint.
I've had this with my '88 Spoiler and just put a copper strip between the "poor contact" pot to a "good contact" pot, best would be to retouch with Silver paint.

[rjw]

Hi Adam,

Thanks for the very clear photographs of the electronics.  The problem is a grounding issue, as the pickup shields are not connected to AC ground.  The long wire insulated with the teflon sleeve on the wiring side of the circuit card is the common / ground lead.  Somewhere along the way, the pickup connectors have been rotated, so the pickup lead center (hot) terminal is connected to ground and the shield contact is connected to the input (hot) terminal to the pre-amp.   Note that the pickup connector has been inserted while orientated with the two slots visible on top, and we need to disconnect the pickup connector, rotate it 180 degrees, and reinsert it with those slots down, so the smooth side of the connector is on top.  Do that for both pickup connectors.

-ron

[Khrist92]

Thank you all for your help. Ron, you hit the nail on the head. Rotated each connector 180 and voila, quiet as a mouse. Thanks again!

[mario_farufyno]

Eagle Eye Ron!

[edwardofhuncote]

Hard to beat getting advice on a Distillate from the Distiller, himself. 


I remember that bass because it was so unusual. It was actually a Spoiler 5 with Point body, long-scale, and Distillate electronics. Quite an unusual custom, maybe unique. Glad it went to a good home!