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  #1  
Old 07-22-2017, 02:42 PM
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Schanz Schanz is offline
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Another Philco 87 question

Brought it to life today but I need to solve an issue with the volume. Seems to be a bad connection like it just needs a cleaning. However, when I do get volume it's just loud, there's no variance. I took the control out and began cleaning the band with deoxit. It is covered in a very thick layer of black. Almost like it was coated on purpose. Should the band be cleaned to bare metal?

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Old 07-22-2017, 03:22 PM
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Ok, so I took the band out and it appears to be some type of carbon. I reassembled and tested and I get zero to 20k ohms.

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Old 07-22-2017, 03:51 PM
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Carbon resistance element pots SHOULD be coated in carbon, don't remove it or the pot will go open/be ruined.
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Old 07-22-2017, 07:47 PM
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I think the volume control pot is part no. 3076, which is 10K ohms. If you're at 20K and want to reduce the resistance, you can sprinkle powered graphite on the carbon element and burnish it with a smooth instrument. If the resulting resistance is too low, just lightly wipe off some of the graphite with cotton. Keep adjusting that way until the resistance and taper are satisfactory.
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Old 07-22-2017, 10:07 PM
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I have the Model 86 with a very similar chassis - my volume pot measures almost 18k out of circuit, and I can control the volume okay. One thing about my Philco, and yours as well - the volume pot is more of an RF gain - with my hand on the knob, I can couple enough RF that it raises the volume, and when I remove my hand, it lowers by 50-75%. So I set it "loud" and remove my hand for a more pleasing volume.

My radio has been in the family since the early 70s. Dad got it from a customer that "needed room" - one 27 tube later, and she played fine. Original cap blocks and filters, no alignment what so ever, and I can tune the AM dial, strong stations only, with no antenna - I get 7 stations out of 11, so I'm leaving it alone.

One thing I do need for my 86 "lowboy" is a pattern for the grille - everyone with one that's intact has declined to trace it for me. One of these days someone will offer up a PDF or a stencil on eBay - another way folks can make money off scarce Philco stuff. It's a back burner project for me...
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Old 07-22-2017, 11:36 PM
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After putting it back in, the volume adjusts nicely but the volume is very low and inaudible if I take my finger off the shaft. It is nighttime though. I'll try again in the daylight but I may need to try the graphite as well go through all the components again.

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Old 07-23-2017, 12:37 AM
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Do you have a longwire antenna connected? Remember, the volume control is in the RF stage, and you've gotta give it some signal to work with.

I'm somewhat urban, with 10 of the 11 AM stations within 30 miles of me. With a longwire antenna, I get only two - the strongest two, bleeding over the others. At night, it's better.

If you are rural or more than 30-50 miles away, you'll want a longwire antenna. Mine is simply magnet wire suspended in my attic, about 25 feet in length. Ground is via a grounding rod outside, also unsure of length, as it was here when I bought the house in '90...
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Last edited by Findm-Keepm; 09-29-2017 at 07:39 PM.
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