Philharmonic Factory Wiring Error?

[Joe Miller]

I am currently restoring a 30 tube pointer dial Philly.  I started with the Amp and found what I think might be a factory wiring error, but not sure.  Here's what I found:

The actual wiring of the C71 500 mfd micas and the R42 (250,000 ohm) resistors were not symmetrical as I expected. When I looked at the bottom view drawing (Riders 14-47) it matched they way the amp was actually wired (not symmetrical). But the schematic (Riders 14-49) shows these components wired "symmetrically" as I expected.

I think the schematic is correct and the bottom view and actual wiring are incorrect, so I changed the wiring to match the schematic.

Has anyone found this same "wiring error" on the amp chassis? Looks like it came that way from the factory, so am I missing something here?

Here's the link to the Rider info. http://www.nostalgiaair.org/Resources/610/M0016610.htm

Thanks,

Joe

[Joe Miller]

Yep, thanks. 

[David C. Poland]

As for the field coil for the Philharmonic pointer dial 15 inch pedestal speaker: should be 925 ohms tapped at 525 ohms.
Voice coil should be 38 ohms assuming the speaker has the proper output transformer as per the diagram.
Maybe the power resistors you found compensate for the field coil you measured at 5K?
Have you asked the seller what he knows about your findings of the radio he sold you?

[Joe Miller]

Hi David,

Yes, I think the intent was to wire the resistors as a voltage divider to provide the voltage that would have been provided by the split FC.  Turns out this speaker may have come from an organ (5K FC vs. 925).  I've corrected the wiring to provide an effective FC resistance of about 980 ohms and a voltage divider to provide the tapped voltage.  Speaker was also wired with the wrong plug so it would not mate with the amp chassis.  I am replacing the plug too.   The voice coil is about 8  ohms and it looks like the output transformer has been replaced to accommodate the lower impedance speaker.

I have the amp chassis all restored and am now beginning the tuner chassis (big job).  I may need to replace the dial glass as some of the green background is missing.  Will be taking it off later today to see.

Joe

[David C. Poland]

Joe,
FYI - the green for the dial a separate sheet of green plastic behind the glass dial. The dial is clear glass with screen painted graphics in white. There are at least 4 versions of the dial. There is the standard 6 band dial with no call letters. There is also the east coast, Chicago (what I have) and west coast versions - these show an additional band above the Broadcast band where local station call letters are displayed and an additional dial lamp to highlight the call letters when each station is tuned reached. The wheel supporting the bank of dial lights rotate with the pointer on the "pointer dial" model, and subsequent "beam of light" models operate the same way but without the pointer.

Incidentally, I have seen two Philharmonics with brown instead of a green backer. Be careful with the lettering on the glass. Although I successfully cleaned mine once, that was 50 years ago when the dial and paint was far newer. Radio Daze offers a number of reproduction E H Scott dials under graphics http://www.radiodaze.com/default.aspx

[David C. Poland]

RE: the receiver chassis, a couple less obvious things to address.
- The rectangular unit (tone reactor) left rear top between the 3 rd audio 6J5's and the expander 6L7's contains 4 caps to replace.
- Below the expander tubes attached to the inside of the chassis, is a soldered metal box with 7 caps inside to replace.
Otherwise, just proceed in an orderly way. You will need to remove some coil cans to replace caps that protrude through the can bottoms.

[Joe Miller]

David,

Thanks for all the great tips.  I got the dial glass off without breaking it. A small amount of the white lettering has transferred to the green plastic.  Not sure I can fix perfectly but if not will order a repro from Mark at Radiodaze. I'm going to remove the rotating dial to clean and lube the gearing.  The tuning is a bit stiff and I want to free it up a bit.  Hope to do that yet this evening.

Joe