AC Leakage in a Wurlitzer 1100

I’ve got a curious AC current leakage issue with a Wurlitzer 1100.

As part of my restoration, I’ve added a grounded lead to the casing of the junction box. The AC outlet that the juke is plugged into, is wired correctly.

Everything works perfectly. However I can measure 40- 50 volts AC from the junction box chassis (ground) to the mechanism, amp chassis, pre-amp chassis and volume box when the line switch is on and 100 volts AC when the line switch is turned off. Fortunately I measure no current.

It seems to resolve when I unplug the program selector (selection switches, fluorescent lights and general illumination lights).

Of course when I run a ground wire from the junction box chassis to any of the mechanism, amp chassis, pre amp chassis and volume box, the voltage disappears.

Certainly it sounds like I should be running the grounding lead from the junction box chassis to the amp chassis etc. but I’m curious as to what’s causing the AC leak.

Just a WAG---open ground in one, or more of the plugs in J-box ?? Ron Rich

I've had this repeatedly on machines in commercial service. It is caused by slight induced leakage from power transformers. In some designs there are capacitors going from one leg of the AC line to chassis but I don't see these in old jukes. If possible, try reversing the polarities of the internal AC plugs, this will normally kill all or most of it. However, a ground is essential for anything that the public touches.

Ron/NYC

Hi Guys,
While I consider a ground to be "helpful", adding it voids the UL listing, at least here, in California. It can be done, but then one is required to submit the item changed, to UL for re-inspection/re-listing. That being the fact, I try to eliminate as much of the"stray voltage" as possible--turning AC caps around, or, better yet, using correctly polarized plugs and sockets. IMHO, today, the "best answer" is to install a GFI Circuit protector on the line cord. This should ( if installed, and tested, as per instructions), prevent anyone from being shocked by the equipment. Ron Rich

A GFCI line cord is simple enough and I have one!
Thanks

Rob;
Your reply has got me thinking...
If the leakage resolves with unplugging the program selector (with a number of AC sockets involved that power the fluorescents and two 120V AC incandescents) maybe the polarity on one of these ac sockets is reversed.
Thanks again!

utter,
Me thinks, that maybe that was his point ??
Ron Rich