Philco Speaker Frozen - Printable Version
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Philco Speaker Frozen - dconant - 10-13-2024
Hello, I have a Philco speaker where the voice coil seems to be frozen in place probably by rust. I was hoping to remove the cone and maybe clean out the space if possible. The basket appears to have a metal frame around the perimeter. Is this frame holding the cone to the basket sans glue? I was thinking bending the tabs back and remove the frame and hopefully remove the cone. Has anyone attempted this? The cone is in perfect shape. The picture showing the spider shows the cone being out way to far as well as the voice coil picture.
This speaker is from a Philco 91 (code 121) single speaker. I don't know what the readings on this speaker should be but the field coil seems wrong at about 44 meg. Is that bad? The output trans reads 380k ohms and .6 ohms.
Further investigation. When I remove the field coil wires from the output trans posts I get 22 meg. On the primary side of output trans I get 377k. Trans has a center tap where one side I get 360 ohms and the other side I get 376k ohms. Does this sound right? The center tap connects to one of the field coil wires.
Thank you,
Dan
RE: Philco Speaker Frozen - RodB - 10-13-2024
The model 91 late schematic shows the field coil at 285 ohms but the speaker chart shows 3275 ohms for your H7 speaker. So, I would say you have a bad one. Other models with that speaker are 14LZX, 15X, 23X. And I believe your OT primary is also bad. It should read around 680 ohms.
RE: Philco Speaker Frozen - Arran - 10-13-2024
From that one picture it looks like the speaker cone has been pulled out and the spider is stuck on the screw that is supposed to hold it down. As for the Ohm meter readings I would confirm that the meter is reading correctly on something else like a resistor, it's very odd that a speaker would have both a bad output transformer and a bad field coil. You mention that this is a model 91, is it a console or a table model?
Regards
Arran
RE: Philco Speaker Frozen - dconant - 10-14-2024
My 91 is table model with two 42 tubes. All measurements were with speaker disconnected from chassis and field coil disconnected from output transformer. I was afraid they were both bad. My speaker is a K6 (8" not 10") but can't be sure of the 6 because of too much rust. The 285 ohm field coil Rob mentions sounds pretty low by me but I'm no expert. Could I use another speaker with a field coil around the 3275 for the K6 based on the speaker list? I'm sure my speaker is on line 87 of the speaker list. The output trans part number is 2585 as in the list. With my output trans reading 384 ohms (today) and line 87 saying 680 ohms is my output trans shot? My ohm meter reads a 3.3k resistor as 3.27k.
RE: Philco Speaker Frozen - Radioroslyn - 10-14-2024
It seems like 1/2 of your opt's primary is open, from the center tap to one end. Roughly the total from end to end should be about 500 ohms and center tap to each end roughly 250 ohms. If you are reading 1000's of ohms from the tap to one end it's toast (open). Same w/the fc. If it reads 10's of K it's open (copper rot) and done for.
The only speakers that I can think of off the top of my head are the early "pie pan" speakers K1-3. These have the high resistance fc but the opt isn't going to work out unless you get one from a model 90B 3rd gen p/p 47's. All the others are setup for p/p triode, load resistance too low or single 47 tubes, no tap.
RE: Philco Speaker Frozen - dconant - 10-14-2024
Thank you Terry that's about what I thought. I'll try a want ad.
RE: Philco Speaker Frozen - Brad Winder - 10-14-2024
Before you condemn the speaker, reflow the solder joints of any of the connections you are testing. I have been tricked in the past by corrosion and/or bad joints.