[Winky Dink]

By way of brief introduction, I started vintage radio/TV restoration a couple of years ago. I have no background in electronics, but I've been able to pick up enough knowledge to keep me going through a few projects.

I picked up a very rusty, rodent-eaten Philco 645 this summer and I'm finally approaching completion of the electronic restoration. I got the full service info from Chuck Schwark, thank goodness.

My set is Run 3--stamped on the top of the chassis, and component changes consistent with Service Bulletin 234--except for two things, but I'm only going to ask about thing #1 at this time.

Bulletin 234: "Part No. 30-4114 (.06 mfd.) was added from the C- end of the B.C. resistor to the junction of resistor (66) and (67)."

That additional tubular cap was definitely not in the set when I opened it, but it has had service done. I want to put in that capacitor, but I don't know which of the three terminals on the BC resistor is the "C- end." (As I said--"no background in electronics")

Can someone tell me which is the C- end?

Thanks,
Winky

[Radioroslyn]

Hi Winky and welcome to the Phorum.
The terminal you are looking for is the one that is next to the the ground lug on the BC resistor. It should have a wire connected to it and go to a 1 meg ohm resistor.
OR
IF you connect your volt meter - lead to the ground on the BC resistor. Measure the DC voltage either side of the ground lug. One side will have -10volts or so the other one will have +250 or so. The cap connects to the one with the - voltage.
GL
Terry

[Winky Dink]

Thanks, Terry. I'm looking for causes of some inconsistencies in Philco's voltage specs and my measurements. I placed the new capacitor, but it didn't change my voltage data. The voltages on the BC resistor, however, were -2.7 and -18v! Something's screwy, and I may have miswired one of the Bakelite dual condensers. I'll have to pull the condenser and chase some electrons to and fro. Again, thanks for your help.

[Mondial]

On your radio the BC resistor does not have any positive B+ voltage applied, so your voltage measurements are correct.

The -18 v terminal is the C- end and is where the capacitor should be connected.

[Winky Dink]

Thanks so much for clarifying that. I spent a few hours retracing the wiring and came up with one error--the 8 mfd and 12 mfd caps were reversed (not the polarity, just their positions in the circuit)--and switching those seems to have improved the audio and possibly the reception.

[Radioroslyn]

Hey Wink,
You should post some pics of it here! Some before and afters.
Nice work!
Terry

[Winky Dink]

I would declare that the electronic restoration is complete, but I still don't have anything on the shortwave band. I guess there some issue with the band switch, and I wouldn't even bother with it except that I have a couple of months before I can start working on the cabinet.

Nevertheless, the chassis is done and here are a couple of before/after photos. There's no attempt here to preserve antique value--I'm just trying to make it look close to the original.

[Image: https://lh3.googleusercontent.com/-XeukV...520645.jpg]

[Image: https://lh4.googleusercontent.com/-vfkfE...520645.jpg]

I think I understand the Shadow Meter despite my confusing post in another thread. The meter doesn't respond unless I use my indoor antenna (40 ft. of antenna wire on the ceiling). I originally thought the shadow would reduce to a thin line, but I don't think I'll ever create the conditions to get maximum response from the meter. This is a photo of the meter when a station is tuned accurately. The shadow is narrowed, but can't get any thinner because the vane doesn't return to the center. Some stations give a narrower shadow than this.

[Image: https://lh5.googleusercontent.com/-5DFK3...520645.jpg]

If anyone gets really excited about Shadow Meters, here's a link to a 40-second video of the shadow and the vane movement during warm up and tuning.

https://picasaweb.google.com/coldrb/Febr...directlink

I'll post the cabinet when it's done. Thanks for everyone's help (here and on VideoKarma) in the successful restoration of another radio that I don't where I'm going to put it.

Phixing a Philco is like learning a phoreign language.

- Winky