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Philco 38-116 Audio Input? - Printable Version

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Philco 38-116 Audio Input? - louxwe - 02-23-2015

Just wondering if this is an Audio Input for my Philco 38-116 code 125... haven't seen it on other pictures of this model, surely it didn't come with the original radio did it. I'm guessing it was an audio input added sometime later???? I tried to plug a standard RCA audio plug to see if it it fit but it was a bit snug.... any idea what it is?


https://www.flickr.com/photos/58236519@N00/16309912127/

RE: Philco 38-116 Audio Input? - morzh - 02-23-2015

Yes, looks like audio added by someone, but the surest way to find out is to trace it.
However the most practical way is, when the radio is wirking, touch the central contact with a metal pin held by hand, if it hums, it is then the audio input.

RE: Philco 38-116 Audio Input? - louxwe - 02-23-2015

Yeah haven't got to the point of plugging her in yet, seems like there are some obvious broken wires to look after first, just was curious since I couldn't get a standard plug to fit in very well. I am just getting started and have heard that if it is plugged in wrong the chassis could be dangerous to touch and the audio in plug seems a bit loose so I was worried that it might be a problem if it touches the chassis. Is the 38-116 one of the types that the chassis could be hot? I was also looking at the power plug and it seems pretty old and flimsy ( the prongs wiggle back and forth quite a bit), just curious if I should also replace that and if so do most replace with a modern three prong and if so what do you do with the extra wire, just leave it?

RE: Philco 38-116 Audio Input? - sam - 02-23-2015

lou
1 recap
2 check resisters and replace
3 change cord 2 prong is fine
not a hot chassis I move mine while out of cabinet and playing
plug looks to be a old phono rca plug
I would check wires if ok and works leave it in
sam

RE: Philco 38-116 Audio Input? - morzh - 02-23-2015

One thing I always do before starting on a radio with a power transformer is checking the power tansformer. If it is shot, depending on the radio you might reconsider the whole resto effort.

RE: Philco 38-116 Audio Input? - jerryhawthorne - 02-23-2015

Morzh (see I spelled it right) is correct as is Sam. Always check the "iron" first so you know what your getting into on expense. Those are great radios but nice to know if you have some major expenses to look at. Power transformer, output transformer and field coil. All good then on to caps and resistors which are cheap.
Best, Jerry

RE: Philco 38-116 Audio Input? - morzh - 02-23-2015

Power transformer, though, is more of a discouragement if it is shot. Go try to find that one.

RE: Philco 38-116 Audio Input? - louxwe - 02-24-2015

So how would one go about testing the power transformer?

RE: Philco 38-116 Audio Input? - sam - 02-24-2015

First thing i look for is burnt wire and bubble stuff coming out of wire coating or black wax coming from trans 

RE: Philco 38-116 Audio Input? - jerryhawthorne - 02-24-2015

Louxwe, you pull the rectifier tube and turn the radio on. Measure one plate to ground and then the other with your meter set to some high voltage A/C. You can also measure the filament voltage on that tube base to make sure it is in speck on a low voltage A/c. Be careful, there are some really high voltages off the plates to chassis. You can also do just a resistance measurements with the radio unplugged. Report back.
Jerry

RE: Philco 38-116 Audio Input? - K7Sparky - 02-25-2015

Smell and asphalt dripping are indications of transformer trouble.

Looked at a lot of your pictures & didn't see anything like asphalt dripping out of Xformer.  BTW nice pictures.  Lucky you don't have the rubber insulation on the hook up wire that has fallen apart.

Do the light bulb / dim bulb in series with the AC power and pull all the tubes before trying power on the Xformer - you gotta pull em sometime anyway.  A 25W bulb should be plenty big. With no tubes should be almost no current, only thing I see are a couple of pilot lights.

Anyone know what went on the back of the 3 small speaker frames.  Clean so looks like something has been removed.  Were they speakers?  The mechanical behind the cone looks like passive radiators which seems weird in an open case..  The only diagram I have is Beitman 38-116 and it is a code 121.  Audiophool has a 39-116 also a code 121 and a quick glance shows the 39 uses a 80 rectifier.  Both of those only show 1 speaker.

Cut speaker cone leads sounds like a speaker had a problem.  Someone left the plate lead / choke coil.  My guess the RCA jack was for an external PM speaker.

As Jerry says watch the AC on the plate supply winding.  The 39 uses different outputs but schematic has voltages and gives the PS high voltage as 370 VDC.  As a full wave that would be around 270-0-270 VAC plate winding.  If it is the same as the 39, transformer leads would be yellow - yellow green - yellow.  about 540 VAC yellow - yellow.  Considering: - rectifier loss + rectifier filament would not be surprised to see 600 VAC yellow - yellow