The PHILCO Phorum

Does anyone have a Parts list or the Volume Pot Value for a 41-280 (121)?

looks like 2meg taped at 1meg.
Terry

here's a link to the schematic from Nostalgia Air.
http://www.nostalgiaair.org/Resources/414/M0013414.htm
Terry is correct.

If push comes to shove you could use just a 1 or 2meg pot without the tap. The tap is to add low frequency response at low volume (loudness control).
Terry

Jerry,
In your other thread on this radio (maybe Ron could put the two together) you stated the radio was working before it was recaped. So here are a couple of things I am thinking about. If the volume control reads less than one ohm (I think you said .450 ohm), the radio would never have worked. The other thing is, I don't think the pot could ever change in value that dramatically. You might want to retest it. The pot has three terminals located together and the tap terminal is located at some other point. You want to take your measurement from the two outer terminals of the group of three. Let us know what you find.
Steve

Sorry for the long delay, Just got back to a point to work on it again. I measured the 2 Outside terminals and all the way up, it measures approx. 150 Ohms. All the way down it measures approx 1 Meg. Ohms. About 9/10ths turned all the way up it jumps to the Kilo Ohms range (approx. 49.2Kilo Ohms) before jumping immediately to the 150 Ohms reading. This is consistent and can be duplicated every time.

As Terry and Glenn have stated previously, the original volume control potentiometer is 2 megohms, with a tap at 1 megohm.

You may not achieve a reliable measurement of the potentiometer unless you disconnect it from the circuit.

I strongly suggest you invest in a can of Caig DeoxIT D5 to clean your volume and tone controls. Expensive, but worth it. It will clean controls and switches when other contact cleaners fail. And it does not take a lot, nor do you want to spray a lot in each control since the stuff is expensive. Use it sparingly. Follow that up with a spray of Caig FaderLube F5 (for potentiometers and controls only, not switches).

I've found it is mandatory to clean controls and (especially) pushbutton assemblies of 1939 and later Philcos with DeoxIT in order to achieve proper operation. As an example, I have a 41-226 "Sled" with six pushbuttons. They would not work consistently, even after spraying with a contact cleaner. Just a small spray of DeoxIT on each contact restored the assembly to proper operation, and all six buttons work perfectly now.

Now, after all that...if cleaning the potentiometer does not solve its issues, then look at replacement. But try the DeoxIT first.

Oh, and I'll leave this as a separate topic, since we are discussing a specific, important item (volume control).

Hey guys just for grins take the 2 .01 caps that where hooked to the volume control and connect the loose ends together. If your set is working properly it will play at full volume.
Terry

I do not have 2 1k Caps. I enclosed a pic of the pot.

ps Your pot isn't wired properly as per the diagram. The terminal to the right should be connected to the chassis. the next one should have a .01 going back to pin 3 of the 7C6. The terminal to the left should be connected to .01 cap that goes to the junction of two 470k resistors and a 100uufd cap. Double check your wiring and report back.
Terry
pss Looks like you've got a short where the .01 is connected to the terminal strip.

I was thinking something didn't look right but Value wise only, But the Radio worked before I re-capped it and I replace each cap 1-1.

And here is a Pic of the Original Layout......

I am also buying an Oscilloscope today to help testing. Theoretically I should be able to connect to the left pin on the volume pot and get deflection....correct?

Do you know how to count the pins on loctal tubes?
Terry

I have a schematic, haven't yet but could probably figure it out pretty quick.