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50-1726 FM Alignment & Dial Tracking Problems - Printable Version

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50-1726 FM Alignment & Dial Tracking Problems - Guest - 10-07-2009

I am a newbie to this group and a collector of Philco radios since the mid 80's. I have a Philco 50-1726 AM-FM Radio/Phono console that I am in the process of restoring. I have two questions. I have recapped the audio section and it sounds great. The AM band is tracking just fine. The problem I'm having is with the FM band. The tracking is way off. It is affecting both low and high end of the band. On the low side of the band, a station at 88.9 is coming in around 94 mhz and on the high side 105 mhz comes in at 108 mhz. Most of the tubes were weak in this set and have been replaced with brand new ones. I have done alignments on AM sets but not FM. How do I go about it?

The second question I have is about paper capacitor replacement in the IF, Detector, and AVC section of the set. The Philco Service Manual I have for this model caution's about the placement of caps in the high frequency sections of the set. Since newer caps are smaller and have longer leads on each side of the cap, is this going to create problems with unwanted oscillations and could replacement of these parts make it difficult to align? I did a voltage check on all the tubes and they are within specs.

Any help with restoring this set will be greatly appreciated.

Re: 50-1726 FM Alignment & Dial Tracking Problems - marcapra - 06-04-2010

I'm thinking about buying a Philco 50-1726 and wanted to know what you think of yours. Did you ever get it working well? What finish do you have dark mahogany or light wood? Thanks, Marc.

Re: 50-1726 FM Alignment & Dial Tracking Problems - Raleigh - 06-06-2010

I don't think the longer leads of the modern capacitors should give you any problems. The modern leads would probably behave much the same way as the outer foils in the old capacitor, so there would be little difference. I'd be sure to use the type of capacitor you are replacing, e.g. replace a tubular with a tubular, and ceramic with ceramic (if any). Be sure to dress the leads exactly as the old cap was, so if the old cap was dressed against the chassis, be sure to dress the new one the same, and if wires crossed the old cap above or below it, or ran along side, be sure to run the wires the same way, and the same distance away.

The only reason to replace ceramic with ceramic is because you might not be able to dress an axial-leaded tubular part just the same as a radial leaded ceramic. Then again that might not matter, but I'd play it safe.

The Philco service data, if you can find it, probably has critical wiring locations, with a diagram. I don't know if the Riders data would have that information.