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  • February 21, 2015 at 6:15 pm #6586
    Anonymous
    Inactive

    I’m recapping a Philco 40-165. I ordered all caps to replace paper as 630 volts, but on removal I noticed that cap 46 between the potentiometer and Tube 7C6 has 1000 w.v.d.c stamped on it. Can the voltage really be that high? I mean, can I use a 630V capacitor or do I need to order a 1000 volt one.

    I’m hoping it’s just oversized so I can be be firing this up tomorrow rather than having to be waiting for one silly little capacitor..

    (Next project will be recapping my Marconi 36. Cabinet is beautiful, has not been powered on (I stopped the seller just in time), and it has the original operators manual–I got the bug!)

    February 22, 2015 at 7:26 am #6587
    Dan Walker
    CVRS Member

    I looked up the schematic and the one I looked at is not real clear ,but I do see the dotted line from that cap going to the power transformer.. I would be using the 1000 volt cap.. I can’t make out what the value on the schematic is, but I would wait until I got the right cap.
    You could ask the guys on the Philco phorum. [ I know,,,we all want to try out the radio as soon as possible]

    https://philcoradio.com/phorum/

    February 22, 2015 at 7:40 am #6588
    Dan Walker
    CVRS Member

    I notice that you next project is a Marconi model 36.. that is a large 11 tube set and it has a #82 rectifier tube.
    I don’t know if you know about these tubes but they are mercury vapor and they should be standing upright.. they will glow a purple color and you might think something is wrong.. I suggest you GOOGLE #82 RECTIFIER TUBE .
    You may know all about these tubes, but I just though I would let you know Good luck with the model 3 Marconi.
    Dan in Calgary

    February 22, 2015 at 8:00 am #6589
    Anonymous
    Inactive

    Hi Dan,

    I think that dotted line is because the power switch is on that pot. Nevertheless, I’m not turning this on until I’m certain or have the correct capacitor. If I’m correct this pot would be the tone. I’ve noticed other old radios put the tone on the same knob as the power.

    On the Marconi, no I wasn’t aware. I took basic electronics in the early 70’s in High School when tubes were still very much in use. I know the basics. Thanks for that information!

    February 22, 2015 at 8:31 am #6590
    Anonymous
    Inactive

    Speaking of the on/off switch. I put a fuse holder between the AC line filter and that pot, but have no idea what value or speed of fuse I should use.

    February 22, 2015 at 10:49 am #6595
    Anonymous
    Inactive

    I checked out the Philco forum. The administrator had replied to someone that the plate of 7C6 would not exceed 100 volts and a 600 or 630 would be fine. He also noted that this is indeed the tone circuit. With this in mind I may test with the 630 volt once I have a handle on what fuse value to use but will order a 1000 volt along with the parts for my next project to replace it. wvdc means peak voltage that the capacitor can take on it’s plates–not the average voltage applied to it and obviously 7C6 would have a varying output because that’s what tubes do. Even at that, hard to believe I would need 1000V, but I’ll replace it with a 1000v to be sure.

    March 15, 2015 at 11:07 am #6672
    Anonymous
    Inactive

    I fired up the Philco 40-165 today! …but it still hums. The volume control does not affect it and it’s not real loud but definitely too loud. I also cannot tune any station. It sounds like an AC issue, but I’m sure the recap job is good. When I bought this I was told it hums.

    I checked my recapping job around the power supply area in particular and all is where it should be. I think it would have been hard to mess up with a schematic in front of me and the old electrolytic wires still attached at the time of the recapping, but I checked everything in the area against the schematic to be triple sure. While checking some resistors I noticed the 470000 Ohm (item 45) is reading 523000 ohm. This is actually the Canadian “model 23” so maybe it’s correct. It’s in the area of tube 41E, but the biggest thing I notice is I can’t see any light in tube 41E and it doesn’t get hot.

    Should I be able to see and feel the heater glowing in this particular tube?
    I’ve read that a failed filament can touch the cathode and cause a hum. Is this common?

    I guess my biggest question is “should I be able to see a glow in 41E. If so, I know what I need to do next. If not, Have you any ideas?

    I do read 3 ohms between the two fattest pins and I know one is the filament, but I don’t know where the ground is. I have no tester.

    March 15, 2015 at 4:11 pm #6684
    Dan Walker
    CVRS Member

    Pins 1 and 6 are the heater pins and you should get continuity holding you ohm meter on these pins.
    As far as being able to see the tube glow, I am not sure although I think you should . Check your wires going to these pins and make sure they are connected.. this tube takes 6.3 volts on the heater.

    March 16, 2015 at 5:32 am #6688
    Anonymous
    Inactive

    Hi Dan,

    Yes, connection is good and. I took the bulbs out that light the dial and turned off the lights in the room before dawn this AM and I see no light in that tube. Wierd that I have voltage as well as a resistance reading across those pins. I guess I need to track down someone here that has a tube tester.

    Thank you.

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