The proper way to test the winding insulation is with a HiPot tester or high voltage ohmmeter. A conventional handheld ohmmeter does not provide the necessary voltage to validate the insulation resistance integrity.
Using an isolation transformer alone is a bad idea. If the windings leak you will still see a potential on the metal case that could cause great discomfort if touched. The case will still require grounding. Without the proper instrumentation to test it, using the three circuit plug is a good idea but make sure the outlet you use is a GFI outlet to exercise maximum safety. At the end of the day, the automatic winder may best be suited as a decorative artifact instead of a functioning artifact. If it does work now, it may not work in the future as the winding insulation deteriorates. Bruce Peterson -----Original Message----- From: phono-l-boun...@oldcrank.org [mailto:phono-l-boun...@oldcrank.org] On Behalf Of Philip Carli Sent: Thursday, February 16, 2012 5:45 PM To: Antique Phonograph List Subject: Re: [Phono-L] Does anyone know how to make a Jones Motrola _safe_? Many thanks! Another suggestion I've had is the use of an isolation transformer at the plug - any thoughts on that? PC ________________________________________ From: phono-l-boun...@oldcrank.org [phono-l-boun...@oldcrank.org] on behalf of Greg Bogantz [gbogan...@charter.net] Sent: Thursday, February 16, 2012 8:27 PM To: Antique Phonograph List Subject: Re: [Phono-L] Does anyone know how to make a Jones Motrola _safe_? I believe the Motrola has a metal case. The danger can occur if there is electrical leakage from the internal wiring to the case and its attached metal parts which can occur due to carbonized insulation that can begin to develop a lower resistance. I would recommend first testing with an ohmmeter to determine if there is already leakage from either of the wires leading from the motor to the case. An ohmmeter reading should indicate a very high or infinite resistance from either wire to the case when things are correct. If you measure any significantly lower resistance, the internal wiring will need to be redone or repaired. If there is good isolation from the motor wires to the case, I would recommend replacing the line cord with a modern three-wire cord with a 3-terminal AC plug. Connect the black and white wires to the motor circuit as was done in the original 2-wire cord. Then connect the green wire to a screw on the metal case. This will privide a grounding connection from the case to your household earthing system. If electrical leakage should develop in the future, it will be routed thru the green wire to your household ground system (assuming you plug the cord into a modern 3-wire outlet). In the worst case, it will blow a fuse or circuit breaker rather than leaving the system a shock hazard. Greg Bogantz ----- Original Message ----- From: "Philip Carli" <philip_ca...@pittsford.monroe.edu> To: "Antique Phonograph List" <phono-l@oldcrank.org> Sent: Thursday, February 16, 2012 7:08 PM Subject: [Phono-L] Does anyone know how to make a Jones Motrola _safe_? > > I have a Jones Motrola I'm trying to rewire, but I read that they can be > dangerous in their original ungrounded state? Any ideas on how I can deal > with this? Any help would be appreciated. Thanks, Philip Carli > > ________________________________ > > This email message and any attachments may contain confidential > information. If you are not the intended recipient, you are prohibited > from using the information in any way, including but not limited to > disclosure of, copying, forwarding or acting in reliance on the contents. > If you have received this email by error, please immediately notify me by > return email and delete it from your email system. Thank you. > _______________________________________________ > Phono-L mailing list > http://phono-l.org _______________________________________________ Phono-L mailing list http://phono-l.org ________________________________ This email message and any attachments may contain confidential information. If you are not the intended recipient, you are prohibited from using the information in any way, including but not limited to disclosure of, copying, forwarding or acting in reliance on the contents. If you have received this email by error, please immediately notify me by return email and delete it from your email system. Thank you. _______________________________________________ Phono-L mailing list http://phono-l.org _______________________________________________ Phono-L mailing list http://phono-l.org
