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Philco 37-650 Tone Sw. - Printable Version

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+--- Thread: Philco 37-650 Tone Sw. (/showthread.php?tid=2315)


Philco 37-650 Tone Sw. - planigan - 03-31-2010

I had occassion to take one of these apart to try and repair it. Came across an interesting "kink" in this swich. The switch is designed to choose four different ground paths which will affect the tone of the set. There are a total of four positions, in one it connects to nothing (second position). The switch body is physically grounded to the wiper and there are three terminals for cicuit connections (no wiper connection). The switch is an open design with only the pwr sw enclosed. I mention this because on a unit (37-650) that I'm working on there is no ground connection and there is an insulating circle of "fish paper" between the switch and ground so I have to look into that. If the switch body is to be grounded (and thus the wiper) why the "fish paper? The point of this post is that while working on the switch I noticed that the lug used to keep the switch oriented (keep it from turning) when you tighten it to chassis is directly in front of the third switch position and in this case was bent back to the point where it made contact with the third terminal. If left that way, no mater how the switch was turned, it would always be in the thrid position as far as the circuits are concerned. So if anyone out there doesn't seem to get any tone change when the switch is turned from position to position, check and see if that tab is grounded to the third terminal as mine was. Fix just involved small screw driver prying it off the terminal. It most likely got bent when someone didn't get the tab in the hole for it in the chassis and tightened it, bending it back agaInst terminal. (Philco part # 42-1184) PL

Re: Philco 37-650 Tone Sw. - Ron Ramirez - 04-02-2010

Hi Planigan

Thanks very much for the info!

Re: Philco 37-650 Tone Sw. - planigan - 04-03-2010

I have review the switch I have mounted in the 37-650 unit I am restoring and found that even though it has "fish paper" insulator between switch and chassis on the inside, the threaded shaft and nut on the outside ground the switch to the chassis and thus the wiper. Only explaination I can think of for insulating on inside is to prevent terminals, which are located on face of switch, from shorting to chassis. Anybody have any other ideas on this? I am surprised that an extra part was used when it could have been avoided by bending back terminals to avoid the shorting. PL