Hello,
I have a Philco 49-909 that was my great grandmothers and would like to hear it play again. I replaced all the tubes except the 117Z3 tubes. It just hums...the humming seems volume adjustable...but there are zero radio stations to be heard. I am a complete and total novice but I do know how to solder...lol. Is there someone here familiar with this radio that can steer me in the right direction?
For starters you need to replace the electrolytic capacitors, and in fact all the paper capacitors in the set. I wouldn't operate the set again until you have done so.
What would the result be of a failed 117z3 tube?
If the 117Z3 were dead, the radio would also be dead.
Codefox has given you excellent advice; what he said is exactly what needs to be done to your radio. The humming is caused by bad electrolytic capacitors. These need to be replaced, along with all paper capacitors, else the radio never will work correctly.
Okay so I gotta replace the caps. I was looking at the schematic and parts list and noticed a 4 way cap being C104?? Can someone give me some insight to that one? Remember, I'm as green as a gourd...
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The filter capacitors (all 4 of them) can be replaced by modern equivalents. You can either disconnect all wires to the "can" and mount them under the chassis, or gut the can, melting out the tar, etc... and stuff the new ones inside.
You can use or 33 mf caps to replace the 40 mf sections , and 22 mf to replace the 20 mf ones. Observe how they are hooked up. If the 117Z3 dies, you can replace it with a silicon diode and a 100 ohm 5 watt resistor, but let's not go there yet.
I would go with 450 VDC versions, as they are only pennies more. Replace all the paper capacitors as well with 630 volt mylars, and you should be good to go. Make a complete list of what you need lest you have to pay twice on shipping.
Several great vendors for small orders are available. One is
http://www.justradios.com . Others will mention more sources, I'm sure.
I'm trying to figure this out...So, I have a paper cap that states .04mfd 400 wvdc. I don't see a .04 mfd on justradios...I take it this can be substituted with something else? Like .0047uF @ 630V maybe? Also, the black stripe on the end of the paper caps..is that the + end?
THe .04 could be replaced by .047 or even a .05. The black stripe on the old wax cap indicates the outside foil, and is of no particular importance 99.9% of the time. You can always reverse the leads if it becomes critical. The outside foil was typically tied to the ground or B- in the original manufacture of bypass circuits, and remained irrelevant in other applications. Modern equivalents are much smaller, and therefore have much less tendency to radiate or absorb any external signal. Someone once commented that the left side of the capacitor, when you read the value, is the outside foil, but I can't say that is true. Someone out there might know.
Just follow the original lead dress, insulate the leads with shrink wrap, and do one at a time and you'll be fine. If you need to extend the leads, do so before slipping on the heat shrink, and place the new cap where the old one was.
Take a few pictures first, so you will know where to put everything.