Philco 44 - circuit and parts - Printable Version

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Philco 44 - circuit and parts - Guest - 10-07-2008

Hi,

I'm curious if anyone might happen to have an under-chassis shot of a Philco 44. I'm restoring one (a family heirloom) and it was unfortunately worked on at least once in its life. The "repairs" made a mess of the circuit and I'm having a hard time reconstructing everything to original using the component drawing I have from a service manual (4 pages of info). To my knowledge I don't have the actual Philco service data, just something from Sam's or Rider's.

A hi-res under chassis photo would prove most helpful for returning things to their former state. I'm currently rebuilding the Bakelite blocks and have a WTB in the appropriate section for a few that were removed, as well as a few other parts I need. Someone on antiqueradios pointed me here since a member of this forum apparently removes the blocks and has a stash of them.

Thanks!

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Re: Philco 44 - circuit and parts - Ed Locker - 10-08-2008

Hi Zap

I have a picture of the under side of a Philco 44.
Email me and I'll send it to you.

Ed

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Re: Philco 44 - circuit and parts - mandh - 10-09-2008

I found bolts and washer to mount the chassis of my Model 60 available at my local ACE hardware store. My local store has bins of hardware in it. They were #12 sheet metal screws and 7/8' washers.

Harv, WA2AAE

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Re: Philco 44 - circuit and parts - Guest - 10-11-2008

Thanks for the helpful information so far - I'm looking at resistors now.

The list shows "Flexible Wire-wound" but I don't see anything like the ones pictured on one of the Philco sites. I found the carbon resistors and out of the three I've checked one or two might be too far off to keep. What was the tolerance of the originals (wire wound and carbon)? Additionally, what is the wattage rating for the wire wound? I found the ratings for the carbon, which I am going to just pick up spares for in case I need them.

Is it possible there are carbon resistors in place of the wire wounds? A few more modern carbon comps are installed in the radio, but I haven't verified they are all in place of the wire wounds.

Additionally, is there a good way to check the big voltage divider resistor? Can it be probed in circuit, or will I get false readings?

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Re: Philco 44 - circuit and parts - mandh - 10-13-2008

If the radio has been worked on previously, they may have replaced the flexible resistors with carbon units. My Model 60 has a flexible resistor in the mixer stage cathode circuit and a carbon resistor would work in its place.

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Re: Philco 44 - circuit and parts - Ron Ramirez - 10-13-2008

I believe most of the old carbon dogbone resistors had a 20% tolerance.

There is no reason why you could not use a carbon film resistor to replace the flexible wirewound resistors. 1/2 watt works well for most of these.

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Re: Philco 44 - circuit and parts - Guest - 10-18-2008

A bit of an update - I'm making progress!!

I'm slowly tracing the entire circuit of the radio, reinstalling some of the rebuilt bakelite blocks, reconnecting wiring to them. I have two more blocks coming to me to restuff so I can restore the underside of the chassis to its original state. The only parts I still need are the safety capacitors for the line bypass.

I also have a bag of all the resistors present in the chassis that I got as insurance in case the existing ones have drifted. How critical are the values for proper operation? I'm trying to make a call between a full electrical rebuild vs a functional restoration. For instance a 50k is reading around 34k so it should definitely get replaced (above 20% drift). Do you generally leave the carbon (dogbone) resistors in place if they are within tolerance of modern carbon resistors (10% or so?) or should they be replaced due to the fact that they will likely age and cause trouble before too long?

I'm also curious what the opinion is on inrush current limiters (NTC) and generally what size is recommended. I have an extra laying around from a tube audio amp project.

Thanks for the input

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Re: Philco 44 - circuit and parts - Ron Ramirez - 10-18-2008

As the original resistors had a 20% tolerance, I would say if the resistors in your set are within 20%, then leave them if you want to maintain original appearance.

I do not use inrush current limiters on my sets, but many people do. To each his own. CL-90 is the part generally used for this. Someone will chime in with the specs; I just got up, and do not remember them at present.

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