Hey jcassity - I have about 260v on the plates of the 6V6 tubes. The Philco documentation says it should be 235. I'm measuring with a digital multimeter so I would expect my readings to be higher than the specs say.
The resistor I'm concerned about is the 15k 2W resistor in the power supply. It's R100 on the Philco schematic, R127 on Sams.
It's connected between the 2 can capacitors. It will be a few hours before I can take a new reading because I'm in the process of re-replacing some wires. 2 years ago I replaced some of the high voltage wires with some wire I picked up at the auto parts store. I decided it would be a good idea to go back and re-replace those with 600v wires. But when I measured it before it had 166v across it in FM mode, which means it's dissipating 1.84W. Even in AM it measured about 116v, dissipating almost 0.9W. I'll try to get a new measurement later today.
the power supply from 1945 /46,, the 46-1226 code 122, runs 1 thru 3 match more like your 47-1230 !!!!!!!!!
so you are a 47-1230
I am a 46-1226
my gut feeling is Philco discovered the power supply revisions to allow for a pm speaker 46-1226 code 125 runs 1,2 & 3 sucked!
since my model suckuthed with great magnitued, ,,, what they did was build your set for 1947 but they re-employed the power supply of late 45 and early 46 model years.
so... there's probably a few serial numbers out there with my code 125 that are red headed step children.. with this goofy layout.
~~ my assumptions based on material evidence provided in older and newer prints from what i have all the way up to your posting above.
my 46-1226 code 125 run 3 radio was philco's first attempt to do a PM speaker.
they found issues after owners had complaints
they went back literally to the drawing board
They have shown you and I in writting that the code 122 power supply layout would work better so thus your 1947 radio mirrors a much older power supply layout.
this is probably why you didnt have the problem i had with having to calibrate a large resistor like i did.
here i have attached proof.... from older Left to right and then you!!,, your prints illustrate proof that the 46-1226 code 125 was inferior.. so in the year 1947,, they reverted back to an older layout from late 45,, to early 46 style for the power supply.
get it?
meaning this is why i cant help on your question.
(This post was last modified: 02-12-2019, 01:49 PM by jcassity.)
Ok...thanks for your help jcassity! Anyone else out there with a functioning 47-1230 on their bench that could make this measurement for me?
If I can't find a solution and everything seems to be working ok I'm considering installing a 5W resistor in place of the 15k 2W resistor just to be on the safe side. I took a new measurement and it is better now that I have FM working, but is still dissipating 1.55W when in FM mode, 0.84W in shortwave, and a little less on AM. There are also (2) 0.5W resistors that this circuit feeds that are dissipating a little less than 0.25W so I'm considering replacing those with 1W resistors. I'd really rather not do that if there is actually a problem in the radio but without comparing to a know good radio I don't know for sure.
it may sound like a lot of work but..... i think i can tell by some pics that you kept a lot of original resistors.
i have thousands of resistors if you get me a list of what you want... i can gather them up at no charge... then mail out to you.
to be honest,, im betting somewhere some how something about a resistor not being correct might be helpful.
also,, you may wanna play it for hours then come back and feel the heat coming off each resistor... or with a laser temp sensor.. see which area is hot... or if you have an app on your smart phone to do that or a camera IR type.
I personally would lay the radio on one of its long "sides" so that the underside components are facing you and the tubes / transformer are pointing away from you so the heat rises up into free air. this would be a reasonable way to get accurate heat monitoring readings when you check resistors by your method of choice.
i see what you are trying to achieve,, funny how this part kept me working on the "working radio" for a couple more weeks till i made various heat syncs, yet your finding yourself here as well...
i guess you could wrap that particular resistor with braided shield and bond that to the physical chassis... to wick the heat off.
most people here would probably say ,, "these sets have a lot of hot spots,, just put a bigger wattage resistor in there to get the heat down if you dont like it",, which i agree with. but your gut is telling you that something downstream is causing this one to get hot... same issue i ran into.
i ended up moving my pain in the butt resistor up to the top and doing it like this,,, which calmed everything down really good.... but it was considered and very extreme maneuver.
this might appear ridiculous but its how i ended up calibrating the heat "OUT". its the tall green thing in the pic.
i am by far no expert but what i have learned is if your IF voltages are not right,, it could cascade in either direction,,,, so maybe an easy thing to do now is let it cool down,, and do a resistance check on IF primary & secondary sections,,, yet with wires hooked up,, i would be compelled to disconnect wires to isolate the IF's,, thats just me.
(This post was last modified: 02-12-2019, 01:32 PM by jcassity.)
whats really odd here for you is that your resistor your questioning is darn near if not identical to the same location within the circuit as the one i had to deal with.
yours is like mine,, right off pin 8 of the 5y3,,,
yours is 15kohms,, mine being whatever i calibrated it to even though the print says 300ohms.
(This post was last modified: 02-12-2019, 01:46 PM by jcassity.)
(02-12-2019, 01:14 PM)jcassity Wrote: it may sound like a lot of work but..... i think i can tell by some pics that you kept a lot of original resistors.
Actually, I replaced every single resistor on the main chassis except one, and several on the tuner sub-chassis that measured out of tolerance.
I may actually be chasing my tail now. I had it running for a couple of hours while I was fiddling with the alignment (again). When I shut it off I decided to get brave and carefully touch the 15k resistor. It was on FM for quite a while so I figured it would be too hot to touch for more than a split second but it really didn't seem that hot. I'll try it again the next time I have it running but if it really isn't that hot I can't explain how it could be dropping 151v, which means it's dissipating 1.5W, and not be quite hot.
But now I have another problem [Image: http://philcoradio.com/phorum/images/icons/sad.gif] I'm not getting anything but a nasty sound through the mixer/oscillator. I need to get this thing working and leave it alone LOL. It does something different every time I work on it!
I think I'll think about that one while I remove the dial backplate and paint it. I put some tape on it so I could mark various points on the dial and when I removed some of the tape some of the paint came with it.
I experimented with several different types of paint and it looks like Rustoleum Copper comes closest to matching.
That last problem I mentioned (just noise through the mixer/oscillator) was just a big operator error...no problem and all is good. So I'm in the process of painting the dial backing plate. I lied about the color I'm using. It's actually Rustoleum Metallic Vintage Copper.
Once that's done I'll investigate the current draw through the 15k 2W resistor further and decide if there is really a problem. I'll also do some work on the shortwave to see if I can get that working better. But otherwise, I think this thing is close to reassembling and surprising my mom with it!
Actually, the Metallic Vintage Copper is darker than the original. I changed mid-stream and shot it with some Rustoleum Hammered Copper because I thought the color matched better. But I didn't like they way it looked so I'm sanding that off and will go back to the Metallic Vintage Copper.
From your schematic in post #226 (top of the page) the diagram calls 310 V on one side of R100, and 190 V on the other i.e. you should expect to see about 120 V across your resistor, close to the 116 V you see in AM. The fact you see a different voltage drop when on FM may or may not be significant - sorry, I can't help you there, but perhaps someone knows. Does the voltage differ depending where the radio is tuned on the FM range, whether it is on a station or not - that kind of thing?
At 120v drop across the 15k works out to be abt 8ma @ 1w.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Correct Terry. Here are my latest measurements, with the worrisome readings highlighted in light red:
I'm really not concerned about the R82/R83 combination in FM since there are actually (2) 0.5W resistors in parallel. I need to get a better look at R82...it's buried a little bit. But it looks more like a 1W than 0.5W. If so, then those readings aren't quite as bad but still worrisome. The one that really bothers me is R127 in FM. I'll do more research and testing but it may be a day or two.
humm, you almost lost me but i scrolled through (back in time) to the resistor you just spoke to.
R127 and R100 are the same component depending on which print you look at (sams or philco).~see post #226
E^/r = about 1.5watts from the mountains here in wv if your 151v drop is applied.
what we know is ........
the worse voltage drop you saw was 151vdc across the resistor tied to pin 8 of the 5y3.
This resistor is not stable with respect to the voltage drops you are reporting
Your new tubes installed made no difference
what i personally know is that this resistor is electrically located in the same spot that gave me worries,,, and i was never able to hold my finger on the proper wattage sized resistor for more than 3 actual seconds. the radio continued to work with the OEM recommended resistor that i installed but prior repair man work showed that keeping this resistor under the chassis was radiating heat on various near by parts and actually inducing a melting look to the bottom of my 5y3 tube socket. my only solution was to relocate it out from under the chassis and integrate some sort of over kill wattage value of a calibrated resistance with a fabri-cobbled heat sync. to be fair, the main reasons i had troubles i think was that my push/pulls were runnin' a tad high in voltage,, so i calibrated this resistor to get the push voltage down, which forced my hand to a higher wattage resistor.
what we dont know is the actual resistance of R100/127 when its cool - no load
What we dont know is the actuall resistance of the R100/127 when it is hot - no load
i am guilty of over complicated things just because i turn over as many stones as i can to make this stuff future proof,, i dont like wasting time either.
what i suggest............
de-solder the side of R100/127 connected to the 5y3 - 8.
place your***ANALOG*** ammeter in series there.
Power up and observe the needle deflection and possibly get actual visual amp draw changes based on:
-time
-band switch selection
-wiggle testing of various pieces parts while the BS is in either FM or AM or Sw
(This post was last modified: 02-14-2019, 10:21 AM by jcassity.)
i happen to have a few different shunts lying around because i dont have an analog meter i can put in series with a circuit to read higher amps.
normally (today) we dont really use AmpMeters.... on things. even in automobiles the makers use milli volt drops across a calibrated resistance wire to show you a gauge that is graduated to visually display "amps"... its actually a volt meter !!! on your dash. in all technicallity, cars actually simply apply the difference of potential technique to give you a needle deflection.,, not very accurate nor what would be a good lab tool.
shunts are a lab tool.
we put a shunt in series with the power feed buss or wiring.
this shunt is laboratory calibrated to its specific internal resistance allowances.
it normally has a lug landing screw terminal one each end.
it normally is stamped with its rating in m/V and Amps.
in my case to read high amps i used my spare 100amp 50mv shunt.
Now you can use a cheap analog meter and read the m/v drop across the *shunt*.
Next you use your calculator and as an example..... the formula is
milli volt meter reading / shunt stamped millivolt Rating * shunt stamped amps rating = amps
example--
with your analog meter across the shunt you read .019mv so your amp draw is...
.019mv / 50mv * 100A = .038Amps
(This post was last modified: 02-14-2019, 10:50 AM by jcassity.)
