A question or two for Philco enthisiasts. - Videokarma.org TV - Video

BostonDave · #1 03-30-2009, 09:00 AM

I have a Philco 39-25 which looks identical to every 39-25 I've ever seen except that instead of 8 auto tuning buttons it only has 6. Inside there are slots for 8, but the escutcheon only has a place for 6 buttons. This is probably a Canadian set. Were there any variations for Canada-only models that anyone might be aware of or is anyone familiar with a normal 6 button variation.

Cleaned and used some deoxit and the tube amp in the unit works although the volume seems limited - (I can play a CD or a guitar through the RCA input on the back), but the tuner section isn't working yet. The seller told me it was working about a year ago but he was only getting one station then. I was wondering where to start for troubleshooting of the tuner section. There are about 8 screws in the back for fine tuning the AM bands. Should I attempt adjustments there or just go ahead and replace all the electrolyte caps first?

I've also come across this Philco floor model (see attached) and wasn't quite sure from the picture which model it was. It appears to me to maybe be a 39-770XX but I can't tell from the picture whether there was a hinged door for the dial/control section. It appears to have 7 tubes. Is anyone else capable of identifying this with more accuracy? If it is a 39-770XX what was the deal with a "tropical" model, and aren't these very rare? (I've seen one site which says that the production quantity for 39-770XX and the 39-2770XX added together was only 200).

toxcrusadr · #2 03-30-2009, 02:07 PM

Is that 39-25 a slant front table model? If so I have one of those and will take a look at the buttons. I prefer not to even run them until the paper foil capacitors are replaced. It's only a few bucks and the radio will most likely spring to life. The B+ may be low due to leaking electrolytics in the PS, and if they fail it's bye bye power tranny or rectifier tube. The paper foils in the rest of the radio can lose a lot of your signal too. I would recap before bothering to attempt alignment.

Nostalgia Air should have the schematic and hopefully alignment info, or the Philco Repair Bench site.

On your floor model, you may want to peek in the photo archives at Radio Attic for an ID.

BostonDave · #3 03-30-2009, 08:15 PM

Quote:

Originally Posted by toxcrusadr

Is that 39-25 a slant front table model?

Yeah, that's the one. You don't happen to have a cap list by any chance? I got the schematic from Nostalgia Air and a lot of the caps don't match what's in the schematic. I think I can pretty much figure out what I need from looking at the originals. Again I'm not sure if I have a slightly different Canadian model or something (6 push buttons instead of 8).

Also two of the three big aluminum encased electrolyte (16mf/250v and 8mf/400v) caps had been disconnected at some point and the wires are gone. Not sure why this would have been done. Would the radio work without these? Perhaps the low volume is related? I'll have to try to figure out where these are connected using the schematic.

toxcrusadr · #4 03-30-2009, 11:28 PM

Yikes, no, it will not work right w/o the electrolytics! They are essential to producing clean B+ to make the tubes work.

I looked at mine, it has 8 pushbutton holes. I say holes because the buttons are long gone.

I would replace whatever values are actually in the radio. Philco, IIRC, made a lot of undocumented changes midstream, or you may have a different version as you mentioned. Just read the caps and replace what's there.

If you can't figure out those electrolytic connections let me know and I might be able to pull the chassis out of mine and photograph the underside. I can't guarantee it'll happen right away though.

jeyurkon · #5 03-30-2009, 11:48 PM

Quote:

Originally Posted by BostonDave

Yeah, that's the one. You don't happen to have a cap list by any chance? I got the schematic from Nostalgia Air and a lot of the caps don't match what's in the schematic. I think I can pretty much figure out what I need from looking at the originals. Again I'm not sure if I have a slightly different Canadian model or something (6 push buttons instead of 8).

Also two of the three big aluminum encased electrolyte (16mf/250v and 8mf/400v) caps had been disconnected at some point and the wires are gone. Not sure why this would have been done. Would the radio work without these? Perhaps the low volume is related? I'll have to try to figure out where these are connected using the schematic.

Are there similar value caps under the chassis? Perhaps they replaced the cans and left them in place for the look. If there are no dangling wires I would guess that this might be the case.

John

BostonDave · #6 03-31-2009, 08:57 AM

No. Of course. They were simply bypassed using two large paper caps which match the specs. I guess this was/is common practice. I imagine I'll just replace them the way they are, and probably bypass the third can as well when I recap.

As for the caps not in the schematic I had decided already to go with what is in the chassis vs the schematic. All of the original caps in there have Philco part numbers on them so for the ones that don't have specs printed on them I should be able to pull the specs off of the schematics from other Philcos from around the same year.

The only other quick question I had was about the way the RCA input is wired. It has two wires coming out of the back of the input jack and both wires are sliced together like a 'Y' before leading. It works, but the wiring just seems strange to me.

Toxcrusadr - I don't know if you are thinking of restoring yours or not, but in case you wanted new buttons this guy seems to have the best price I've seen around.

http://www.antiqueradioknobs.com/partlistings.html

The 1941 Philco Pushbuttons will fit the 39-25.

toxcrusadr · #7 03-31-2009, 10:37 AM

Thanks for the button link. I have about half of the slant front series collected (there were 8 different cabinets) but stopped due to lack of space. I always wanted to have a big wall rack with all of them on display. Who knows when I'll get to restoration on these. So many radios, so little time. Meanwhile they are fun to look at.

Tom Bavis · #8 03-31-2009, 11:44 AM

I have the Philco Service Bulletin for the 39-25 on my web page: http://www.audiophool.cjb.net/Philco.html

Riders usually just copied Philco service data, so it may not be any different... I also have the '39 Philco yearbook and a CD of Canadian schematics... I can take a look.

BostonDave · #9 03-31-2009, 12:37 PM

Thanks Tom. I was already at your site and indeed Riders seems to have just copied the service data so it's the same as the stuff I got from Nostagia Air. I'd be curious to see if the Canadian specs are different, but should be ok doing the recap with what I have already.

You seem to be into Philco pretty heavily. Any interest in taking a crack at identifying the Philco console in my first post up-thread? Here's the image of the 3970xx which I think it might be. The lack of push buttons is what makes me suspect it's that model.

toxcrusadr · #10 03-31-2009, 01:21 PM

I wish I had more to contribute on that 3970 but I can tell you those are nice radios. I have a '41 model, can't remember the number but here's a pic. The styling on it is just so cool. Alas I am going to have to sell it soon as I'm running out of space.

Reece · #11 03-31-2009, 01:43 PM

Hi, Dave. Looking at the schematic on Nostalgia Air for the Philco 39-25, I don't see a phono input. Maybe somebody added it. How it works would depend on how he connected it. You say the wires sort of join together after they leave the RCA jack: is it a shielded cable as it should be? Then it would look that way. If you could trace the wiring and report back would be glad to comment.

Try this: put your finger on the grid cap of the 75 tube: should get a loud hum which means the audio section is OK.

Be sure the bandswitch is in the "manual tuning" position for the dial tuning to work. Nostalgia Air says this is position two.

As to the electrolytic caps, common practice is to leave the old cans in place for looks and replace with modern electrolytics below the chassis, which are much smaller. Old ones should not be bridged but taken completely out of the circuit. You can get 8 or 10 mfd. at 450 volt, and 15 or 22 mfd at 250 volt, to replace the three caps in the radio. Notice that cap #41, the 8 mfd., does not have negative connected to chassis. The other two electrolytics do. Philco's schematic symbol for the electrolytic represents the negative side towards the bottom of the drawing, as the U-shaped "can" part of the device. They would have been more helpful just using + and - on the drawing. With modern mini electrolytics, the aluminum can showing on one end is the negative, the wire coming out of the insulating disc end is positive. As already posted above, I wouldn't play the radio any more until paper caps and 'lytics are replaced. Don't want to fry that 84 or the power xfrmr.

I hope I didn't spout a whole lot of stuff you already know! Sometimes I get carried away.

Reece

BostonDave · #12 03-31-2009, 09:35 PM

Quote:

Originally Posted by toxcrusadr

I wish I had more to contribute on that 3970 but I can tell you those are nice radios. I have a '41 model, can't remember the number but here's a pic. The styling on it is just so cool. Alas I am going to have to sell it soon as I'm running out of space.

Yeah. Most of the Philco consoles seem to have cool styling from the late 30's and early 40's. The one you have is very interesting.

BostonDave · #13 03-31-2009, 09:52 PM

Reece. Appreciate your post. A lot of good info in there.

I had noticed on the radio itself that cap #41 isn't grounded either. There's just the positive lead coming out of the can and I can see no evidence that there was any other wire soldered where the negatives were on the two others. I wasn't sure what to do when replacing that one. Should I ground it to the chassis or leave it without a ground like the original?

I got a cap list together tonight from looking at the actual caps and have the mfd values for all of them. At least half of them are different from what's listed on the schematic and parts list.

There are a bunch that don't have any voltage printed on them and there doesn't seem to be any voltage in the schematic or parts list for them either. I think I vaguely remember coming across a vintage radio web site where you can order caps from that said something about all the small caps being a certain voltage for that model radio. Does that sound like it makes sense or am I making crap up?

Case be the later, is there a way to determine the proper voltage rating for these?

Oh yeah, the phono input. I looked for that on the diagram as well but couldn't find it. I read somewhere that the rca jack on 39s was indeed an input and it was original, but was a sales gimmick more than anything because television was coming right around the corner and the presence of the input was somehow supposed to convince people that these radios would be compatible with the new technology. Not sure how that was supposed to be, but today it is a great thing to have on there to allow a CD to play (in mono) or even better, a guitar.

I won't be turning the radio on again until I've got it recapped.

toxcrusadr · #14 04-01-2009, 09:31 AM

Most of the small value caps used in radio circuits (other than the electrolytics) can be purchased in 600 V rating for about the same price as 250 V or 400V. 250 will not be high enough for all of them, 400 will probably cover 90% of them (a few places in some circuits see 450 or 500V such as at startup), but 600 is safe anywhere. So if you can't figure it out just use 600V caps and you'll be fine. Or if you can relocate that website you mentioned...

Re: TV capatibility, the idea was that early TVs could be made without an audio amp or speaker, and would feed their signal to the radio through that jack similar to a turntable. The very expensive new TV technology could be made cheaper and a little more accessible that way.

Reece · #15 04-02-2009, 12:42 PM

A good place for caps is Just Radios,
http://www.justradios.com/capacitors.html
...good folks, and very helpful. They sell the yellow caps in 630 volts and those can be used to replace all of the ones rated for lower voltage in your set. They sell the electrolytics as well.

I was just noting that cap #41 does not have its negative connected to circuit ground but the other two electrolytics do. Cap #41 has its negative connected to the center tap of the high voltage secondary of the power transformer, as shown in the schematic on NostalgiaAir. It has to be connected for the radio to work, if not connected there would be major hum.

If this has an RCA jack, I'm betting it's not original. RCA was the enemy and Philco wouldn't use their metal tubes, much less their phono jack. I'm not sure, but think the RCA jack was invented a year or two after this radio was made, anyway. And I don't think you mentioned any way to switch from radio to phono on your radio, which wouldn't be a good way to sell a new set. My guess is that somebody added this input.
Reece