04-16-2009, 12:36 PM
Hi. I am new here.
I have just bought myself a project - a Philco 20 Lowboy. Since sometimes there are different understandings of what it is - here s a link to it.
http://www.tuberadioland.com/philco20_co..._main.html
or our own gallery
http://www.philcoradio.com/gallery/1931a.htm#b , the picture of BABY GRAND CONSOLE (Model 20)
The speaker inside this radio is like this one:
http://www.radiolaguy.com/images/speaker...coSpkr.jpg
Well, the speaker happened to miss major part of the cone.
I spoke to Hank Brazeal, and he, having called this speaker "a big mistake by Philco" recommended first to check the field coil etc.
It does seem like the field coil exhibits 3050 Ohms of DC resistance, when check by a meter.
The transformer on the speaker does seem to have one winding showing 300 Ohms. Another one is in parallel to the voice coil, so I do not know whether it is OK, or ot is the voice coil, although I suspect it is OK (secondaries are usually thick wire, so it is not likely to break).
So I am almost ready to send it for re-coning, but here what I do not understand so far: the plug has 4 pins. However only 3 pins will be buzzed, and 4-th wire is unconnected. The there wired go to field coile and the secondary (mentioned 3050 Ohms and 300 Ohms, one pin is shared) and the 4-th one is soldered to a contact on the transformer but does not go anywhere.
This is not in agreement with the schematic that shows all 4 pins connected (field coil in series with transformer's primary centertap, both field pins connected and primary ends connected).
So unless I am mistaken one of the primary's ends is unconnected (broken>)
then I have another diagram from this website
http://www.philcoradio.com/tech/speaker.htm
Which shows the connection that would buzz exactly as what I have, and this is why I thought that maybe what I have is OK. But then it is nto for Philco 20. Or is it?
So, if anyone knows that speaker/xfmr connection - can you tell me whether you think my xfmr is shot or not? And can the speaker be restored after this or not?
I have just bought myself a project - a Philco 20 Lowboy. Since sometimes there are different understandings of what it is - here s a link to it.
http://www.tuberadioland.com/philco20_co..._main.html
or our own gallery
http://www.philcoradio.com/gallery/1931a.htm#b , the picture of BABY GRAND CONSOLE (Model 20)
The speaker inside this radio is like this one:
http://www.radiolaguy.com/images/speaker...coSpkr.jpg
Well, the speaker happened to miss major part of the cone.
I spoke to Hank Brazeal, and he, having called this speaker "a big mistake by Philco" recommended first to check the field coil etc.
It does seem like the field coil exhibits 3050 Ohms of DC resistance, when check by a meter.
The transformer on the speaker does seem to have one winding showing 300 Ohms. Another one is in parallel to the voice coil, so I do not know whether it is OK, or ot is the voice coil, although I suspect it is OK (secondaries are usually thick wire, so it is not likely to break).
So I am almost ready to send it for re-coning, but here what I do not understand so far: the plug has 4 pins. However only 3 pins will be buzzed, and 4-th wire is unconnected. The there wired go to field coile and the secondary (mentioned 3050 Ohms and 300 Ohms, one pin is shared) and the 4-th one is soldered to a contact on the transformer but does not go anywhere.
This is not in agreement with the schematic that shows all 4 pins connected (field coil in series with transformer's primary centertap, both field pins connected and primary ends connected).
So unless I am mistaken one of the primary's ends is unconnected (broken>)
then I have another diagram from this website
http://www.philcoradio.com/tech/speaker.htm
Which shows the connection that would buzz exactly as what I have, and this is why I thought that maybe what I have is OK. But then it is nto for Philco 20. Or is it?
So, if anyone knows that speaker/xfmr connection - can you tell me whether you think my xfmr is shot or not? And can the speaker be restored after this or not?
