The PHILCO Phorum

I have a couple questions for Ron or whomever.

I am working on a 41-296X with a 41-285 chassis -I think.

I say 'I think' because there are several discrepancies between the schematic and reality.
One is the dial lamps. I have only Two dial lamps in the radio, one for the dial and one for the band selector switch instead of 5 lamps as depicted by (part 66) on the schematic. The band selector lamp is housed in a hinged metal block, attached to the band selector switch with a black dial cord, and with a retaining spring keeping tension on the dial string.
My schematic shows 5 lamps here, and a 1.8 ohm resistor tying into the harness. Since I have only one lamp, that moves up and down into 5 positions instead of 5 fixed lamps, should I still plan to use a 1.8 ohm resistor there, or should that be changed? (Edit: I assume this will be a 1.8 ohm resistor as only one lamp was ever lit at any time, while my single lamp will be more or less continuously lit. QED same difference.)

Next: Someone (a long time ago judging by the aged, yellow 'Pyramid' electrolytic cap) replaced part no. 62 (12 Uf electrolytic) with a 16 Uf cap. Before getting my schematic, I replaced this with a new 16 uf 450 volt electro. Is that a problem? I have ordered a 12 uf to replace my replacement with, but want it done 'best'.

Third; my 84 tube was replaced with a 6X5 with a plug in adaptor. Why? Which is better? Should I trash the adaptor and just use an 84 tube in that socket, or was there a 'good' reason for this change? Is there a good way to fuse the link between the 84 tube and the transformer, so if the 6X5 or 84 let go, the transformer is protected?

Fourth; I am adding a fused link to the main power cord outside the chassis (safety and liability reasons), the radio claims 60 watts power on 110, my math says a 1 amp fuse will do the job (60 watts/110 volts X 1.5= .8181 amps) or should I use a 1.5 amp fuse?

Fifth; (and most frustrating) Part No 3, Antenna Trans.
Mine had Black, rotten rubber wires coming from post nos. 7 and 5 that were cut and twisted together (not stripped). I cannot for the life of me figure these two wires out, especially since A) they both appear original and B) I cannot find part no 8, nor anyplace where this coil would have originally been attached (no solder spots or anything to even indicate it had ever been installed)
I have already replaced every other wire in this set, and all went to where the schematic seemed to indicate, Except these two (one?) wires....Help!

I am Considering adding an accessory jack for ipod, mp3 etc. and think that I would like to add it by unsoldering one of the 540-1060KC pretune coils and splicing in there, so by simply pushing that preselect button, it will switch over to accessory while still using the radio amplifier, tone and volume circuits. Opinions?

Beyond that, this puppy is as Beautiful as a total (and I mean TOTAL, as in 'Damnit Jim, I'm a Doctor not an electrician!') newbie can make it, (thanks to this site and Antique Radio Forums) all rust free and as shiny as new, almost ready for its first power up. Everything seems to ohm out -again to the best a total novice can judge -so is there anything I overlooked?

Thank you so much for your help, and for this site (I couldn't have done this without you guys).
BTW, just to gloat, I got the 41-296 for $60 and have put $204 into the restoration, plus 49.5 hours on the cabinet and only 19 hours into the chassis rewire. (I do not count the time I spend scratching my head and grunting apelike over the schematic)

A type 84 rectifier is basically the same as a 6X5 with an older style six pin rather then an octal base, but since 84s are not particularly hard to find I would ditch the adapter and use an 84. Why the adapter was used one can only speculate, both during WW2 and the Korean war there were sometimes shortages of replacement tubes but it could have happened at any point since the set was built. the two wires cut and twisted together may have been an improvised capacitor called a gimmick. I really think you should start a new thread with any questions you have as this one is long enough.
Regards
Arran

Thank you for moving this Ron.

[attachment=1405] Thanks for the reply Arran, I am going to try to post the schematic for you to peek at.
Posts 6-7 are underlined in red, and on the antenna trans have continuity between them, so I figure the coil #8 is built in. (purple circle) Post 5 is underlined in blue/green.
I just don't see why anyone would link #7 to #5, even with a gimmic cap (edit; external antenna maybe?) -I also do not see where anything else comes off either of those two posts but lines to ground and/or the band selector switch -which are all replaced and accounted for.
Am I just seeing the work of some guy's half baked idea of fixing this thing 50 years ago here,(edit; or some wierd add on of some kind?) or am I completely missing something/being a noob? It's just that the wire was exactly like all the rest (although a bit gummy where twisted together) and the soldering was so perfect... just like every other blob of solder, except for the ones on a Sprague .003 cap that had obviously been replaced at one time and had a 'blob on a blob' if you follow.
Am I just going crazy over nothing on this part of my question?

Update:

Well, the entire chassis has been rewired, e-caps replaced (I did not change any of the mica caps, as I have no clue how to even test them...) All resistors more than 3% off value were replaced (I even tested the brand new replacements to that spec, Radio Shack quality was, well... Everything is clean, shiny and new looking. All points and contacts have been cleaned.
[attachment=1847]
The only wires I did not replace are coming off the transformer, the AC power switch, the bandswitch light and the speaker (more about this in a minute)
[attachment=1848]
So I took a deep breath and plugged it in, with my wife standing by; nervously holding a fire extinguisher aimed at me.
No sparks, no smoke; so I went ahead and turned on the power. I had already done dim bulb tests at 60, 100 and 120W, which is how I discovered that the output transformer was shot, but this was the first full power up with the bulb taken out of series and that big shiny resistor in its place.
Dials lit up, and the 2 41 tubes, the 6X5 (going to order an 84 to replace it soon!) and the 2 XXL tubes all started heating up and cheerfully glowing -none of the 7 series tubes did (7A6, 7C6 and 2 7B7's).
Then I smelled burned insulation and a trickle of smoke came up by the dial lamp.
I unplugged it, turned the chassis on its side and tried again.
Turned out that the wire from the Bakelite block to the power switch (one of the few wires along with the power transformer wiring that I did Not replace, even though I re capped the bakelite block itself) was burning up right at the switch, so I clipped it off and soldered on a new wire. No more smoke, no more burnt insulation smell. The switch performs flawlessly.
But now I am second guessing myself; should I remove the transformer and replace those last few wires? They are braided and seem to be in pretty decent shape, but so did the one running into the switch block... Should I replace the switch altogether?
Next: What should I expect to have coming from the speaker with only the 2 41's the 2 XXL's and the 6X5 (84) tube operational? Is there any troubleshooting or work I can accomplish without the other tubes?
It will be another month before I can afford to buy tubes (have had an unwelcome houseguest since Christmas -which is why I couldn't buy grill cloth -I carefully counted the pattern threads bought more than a Mile of various yarn and thread and made my own on a 1970's craft loom, pics soon!- and had to wait 2 months to order my new Hammond output transformer.)
As for the gimmick cap from posts 5 & 7 on the antenna coil -I am saving that for last, as I want to hear the difference with/without it.
I still have the original grill cloth carefully stored, and as I said somewhere else, it has some cat damage and a stain or two. Hopefully tomorrow I can post pics of it and the replacement I made.
Ron or Arran or anybody interested in the 2'X2' original? Plenty of usable cloth for smaller applications. Just let me know what you think I should do after you see it.
Again, thanks for all your patience with me guys; this is my very first project of this kind (wow -tubes and stuff!) and without these and the other forums where I see you posting I would be completely lost.

Before buying a bunch of tubes, check to make sure you have filament voltages at each of the sockets (pins 1 & 8, IIRC) where the tubes are not lit. It may just be a problem with a filament line that has opened up.

You won't get much without the rest of those tubes in circuit. The most troubleshooting you would be able to do is to introduce a signal (touch with a screwdriver) the input grids of the 41's and listen for hum. It won't be very loud.

You also may want to carefully clean the pins of the tubes that do not light. The loctal tubes are known to get corrosion on their socket pins, leading to poor contact and bad connections. It is highly unlikely that you would have four tubes with burned out filaments.

If the transformer leads are in good condition, it might be best to leave them alone. Removing the transformer and trying to replace the wires will probably do more harm than good, since you would have to disturb the delicate connections to the high voltage winding.

Nice work, judging from the pictures. I have a 41-280 that has the separate dial light for each band as shown in the Riders schematic I got years ago from another restorer. All of the other 1941 Philcos I have seen use a single bulb in a hinged holder as you describe. I can only assume that the difference was a cost-saving mid-production change.

I can't believe you wove your own grill cloth. I've never heard of any restorer doing that before.

I don't think you can do much of value without your IF and detector tubes. If you have an oscilloscope you might be able to confirm that your oscillator is putting out near the correct frequencies (high impedance probe on Osc XXL plate or maybe on cap #31 if you have the same 41-285 schematic numbering I do.) With a scope you might also confirm antenna coil and push button operation with a probe at the grid of the 1st Detector XXL. But most of your troubleshooting and alignment will need to wait until you have a full tube set.

You can also carry out basic troubleshooting steps to confirm the final amp functioning by touching the plate side of cap #52 (coupler between plate of 1st audio 7C6 and grid of 41s) with an operating soldering iron and listening for the loud hum from your speaker, but if you can hear any hiss or slight hum with the radio on, this test is probably unnecessary.

My experience with those darned ON/OFF switches is that they are very prone to failure after all these years, but unless you are just itchin' to work on it, I'd leave it in until you need to replace it somewhere down the line. Several people including yours truly have posted methods for replacing the switch. Ron improved on mine. You can search on my screen name to find out what I did and how he improved it.

It was common enough once for people to have service people install a phono plug and switch that would inject the phono signal into the 1st amp circuit, so you could do something similar for your iPod, but I'm not really sure how to do it on this radio. Some people like to short or otherwise disconnect the oscillator so that all of the radio signals are cut off to eliminate interference with the phono (iPod) signal. I've read advice from others about matching impedences, so if you search the forum for "iPod" you can probably find it.

Marcus and Levy ("Elements of Radio Servicing", 1947) have some diagrams how to put in a phono plug and switch into a radio of that vintage, so that might be a good place to look to begin with. The book is available to download for free as a series of pdfs on the Antique Radio Forums. Look in Chapter 12, "Detector Stage -- AVC." (Different editions might have different chapter numbers, but that's what it says in my copy.) Again, impedance matching could be necessary, so search for that advice.

I would not replace the power transformer wires without a good reason. YMMV. Those cloth-covered wires are likely very stiff, but if you don't move them too much their insulation will hold. I looked into replacing some once, but there are so many fine wires I could mess up, that I decided not to.

Thanks for the suggestions and the kind words -to be honest, I mainly followed badrestorer's 41-255 step by step job to see how I should do mine.
If you look closely, I did install the ipod jack in an existing chassis hole, and ran it to the 920-1600KC spot on the pushbutton assembly by unsoldering the antenna coil carefully and gently shrink tubing it. Not sure if this will work, but it is an easy fix if it doesn't.

Oh, here's a fast shot of my grill cloth; the loom was barely big enough, so I have to stretch it into a bit better shape; it will be square and straight when I am done. Next to it is the original cloth (note the bloodstain and cat damage on the right hand side, maybe a couple inches into the material). I chose the colors for the new one using the threads at the edges that never saw sunlight or smoke etc.
[attachment=1849]

Will try your suggestions later today.

My wife thinks it looks closer to correct than I do, but I also tend to be a bit too detail oriented... but it will do until I can afford better. 5,400+ feet of stinking thread...

I am not complaining about only having one bandwidth lamp; it kept the switch wafer rewiring nice and simple.
I wish I had taken 'before' pictures -this whole radio was in pretty sad shape and had obviously survived a flood or two (bought it in a hurricane prone area on the NC/SC border).
It is no exaggeration to say when it came home, you could put your pinky on top and almost collapse the wobbly cabinet. The veneer was peeling and bubbling off the sides and missing big strips, the chassis was rusted, the tuning cap was frozen solid, pushbuttons frozen... and on and on.
(I got so caught up fixing the chassis, I never did clean the points on the tubes; thanks for the suggestion!) Oh, two of the 7 series tubes are silvered all the way to the base, and the other two almost all the way down.
Your on/off switch post was the second one I ever read here, right after the 'rebuilding pilot lamps' post of Ron's, but I am just as glad to leave it for now, so long as it is not a hazard to do so.
I can't get anything accomplished around here until everyone goes to bed and stops bugging me, so I will start testing tube voltages tonight.
Is there some kind of ACME rentals type place where a person can rent an oscilloscope? My sum total of diagnostic equipment consists of a multi-meter from Radio Shack (junk, but good enough for continuity, resistance values and simple voltage), two eyes, two ears and a nose.
Thanks again for everyone's help; I really appreciate it.

I'm not sure about rentals for o-scopes that a restorer would be interested in, although there are companies that rent to corporations. I used to rent them at my last job, but they are very expensive, and they cater to the high-speed digital market. You might be out of luck until you get a complete tube set.

Which tubes are you missing? I understood from one of your posts that you had only the XXLs and the 41s and the rectifier, but if you have the "7" series tubes you should be able to operate the radio and troubleshoot it. I suggested using the scope only as a means to verify the oscillator while you were waiting to buy tubes. If you have filament continuity (which you can measure with your multimeter) you should be able to operate them, so you shouldn't need a scope.

If the radio doesn't play, and you have all the tubes, you can troubleshoot it without a scope, but I don't know any way to verify the oscillator without all the tubes or a scope.

Good luck cleaning the pins and sockets. You could also measure the filament voltages at the tube sockets (as BrendaAnnD suggested above.) If you have voltage on the filament sockets and continuity between the filament pins on the tube, then you probably do need to clean the sockets and pins thoroughly.

If you don't have the pin-outs, you can find them here: http://www.tubedata.info/ Go to the bottom of the page and click on the U.S. flag icon. Navigate through the lists of tubes, and you can download the manufacturers' spec sheets, often several manufacturers for each tube type.

One of your earlier questions was the 16uF vs. 12uF electrolytic. I don't think that change will be a problem. I'm told that capacitor tolerances were all over the map in the old days, whereas today they are closer. The rule of thumb is you can go a little bit higher than the originals, but never lower. Smarter heads that I am can correct me if I'm wrong about that.

On one of my early restorations I accidentally omitted the B+ lead to one of the tubes, and of course the tube didn't work and I got no music. I found it by measuring plate voltages.

You will probably need a signal generator eventually. You can find old ones fairly cheaply on eBay. I aligned my first few radios by peaking the IFs by ear and aligning the AM dials by using radio stations near the frequencies specified in the alignment instructions. It's much harder to do short wave that way, though, because they don't announce their frequencies often, at least not in English.

Verifying the oscillator is easiest of all. You just get another radio (a pocket transistor radio is fine for this). Tune that radio to the top of the band where there is no station. Then tune your Philco to around 1100-1200 KC and listen for a carrier "hiss" on the other radio. If you don't hear it, your oscillator is probably not working.