The PHILCO Phorum
Shadow Meter Coil Resistance On 37-650 - Printable Version

+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Shadow Meter Coil Resistance On 37-650 (/showthread.php?tid=3261)


Shadow Meter Coil Resistance On 37-650 - Pepperoni - 05-11-2011

I've been asking a lot of technical questions so I decided to start this new post in this section rather then the Wated Ads. Philco 37-650. I'm reading about 1.5Kohms across the coil of the shadow meter. Is this within spec?

Thanks,
John

Re: Shadow Meter Coil Resistance On 37-650 - Radioroslyn - 05-11-2011

Sounds about right. I know I've seen the spec. for it but can't seem to find it. I would be concerned if it was higher than 4000 ohms.
Terry

Re: Shadow Meter Coil Resistance On 37-650 - Pepperoni - 05-11-2011

Thanks Terry, I've restored the chassis complete and I'm ready to reassemble all the parts, cap blocks restuffed, IF cans rewired and everything else that goes into a complete restoration. Just wanted to make sure this reading was in the ballpark before I proceeded. My first experience with a shadow meter. In fact I still don't know what it does or how it works. I know that something is adjustable on the coil section that moves a small piece inside the housing but that's about all I know at this time.

John

Re: Shadow Meter Coil Resistance On 37-650 - Pepperoni - 05-13-2011

Now I have a question on part #59A on the 37-650 schematic. The 20ufd filter cap.
http://www.nostalgiaair.org/PagesByModel/219/M0013219.pdf
None of the original cans were hooked up and all the filter caps were slaved into this chassis. I'm restuffing the cans one of which wasn't even an original can and I noticed under the sleeve of one of the other cans that I'm not sure is original or not, no Philco markings or part numbers on it, and it has 20ufd 475V and 10ufd 50V stamped into the can. This coincides with the parts list for part #59 but it only says 20ufd and 10ufd on the patrs list.

I looked up the tube data on the 5Y4 and 5Y3 rectifiers and I believe a 450 volt cap would work fine but I thought I'd better get some expert opinions first. So will a 450 volt cap work in this circuit or should it be a 475 volt or higher? All the caps (including the 10ufd) that were slaved into the chassis were 450 volt but this tells me nothing.

Thanks,
John

Re: Shadow Meter Coil Resistance On 37-650 - Radioroslyn - 05-13-2011

450v units should be fine.
Terry

Re: Shadow Meter Coil Resistance On 37-650 - Pepperoni - 05-13-2011

Thanks Terry! One more item in question. The 10ufd 50 volt #59 that has its negative side going to chassis ground and Its positve side going to the CT of the high voltage output of the power transformer. Most negative part of the radio. Is this correct?

John

Re: Shadow Meter Coil Resistance On 37-650 - Ron Ramirez - 05-14-2011

No! Icon_eek

The positive lead, in this case, goes to chassis ground while the negative goes to B-.

There are some Philco schematics, and I believe the 37-650 is one of them, that incorrectly shows the opposite (positive to B-, negative to ground).

Re: Shadow Meter Coil Resistance On 37-650 - Pepperoni - 05-14-2011

Thanks Ron! Now the question has come up as to whether the 10ufd cap #59 is supposed to be a 50 volt like it says on this can or should it also be a 450 volt cap? Just don't know if I can trust the cans that are on this radio.

John

Re: Shadow Meter Coil Resistance On 37-650 - Radioroslyn - 05-14-2011

50v is fine as it's only filtering the bias voltage.
Terry

Re: Shadow Meter Coil Resistance On 37-650 - ipwizard - 05-14-2011

Pepperoni Wrote:My first experience with a shadow meter. In fact I still don't know what it does or how it works. I know that something is adjustable on the coil section that moves a small piece inside the housing but that's about all I know at this time.

John


Check this site, I haven't read it all yet but it explains how the Shadow Meter works.

http://www.philcorepairbench.com/tips/svctip01a.htm

Re: Shadow Meter Coil Resistance On 37-650 - Pepperoni - 05-15-2011

Thanks Keith! I copied and pasted that one for future reference. Lots of good Philco stuff on that site.

John

Re: Shadow Meter Coil Resistance On 37-650 - Pepperoni - 05-16-2011

Movin' right along. I'm just about ready to apply power to this 37-650. Need to install the new speaker wires and she's done.

Got a question on the shadow meter housing grommet that I bought from RenovatedRadios. Where does it go Icon_confused:
[Image: http://speakeasyradios.com/yahoo_site_admin/assets/images/Shadow_Meter_001.135154945_std.jpg]
If I put the grommet over the end of the housing where it fits onto its frame at the front the clips just won't fit over the grommet. Just not gonna happen without breaking something. Am I missing something here Icon_confused:

John

Re: Shadow Meter Coil Resistance On 37-650 - Radioroslyn - 05-17-2011

Hi John,
I'd just shoot a quick note over to RR and see what they can tell you about it. I've dealt with him before on a mask for a 1948 Motorola TV. Seems like a nice guy.
Terry

Re: Shadow Meter Coil Resistance On 37-650 - Pepperoni - 05-17-2011

Thanks Terry! Already done and yes Ed is a good guy.

John