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Restoring a Philco 38-1 - Printable Version

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Restoring a Philco 38-1 - Guest - 05-17-2006

greetings to all:

I am a newbie to this list. A friend gave me an old 38-1 console that had been in his attic for years. It has sat in my garage for about two years, but I'm now working on restoring it. It's quite beaten up, but it appears to be mostly cosmetic (lots of scratches and scuffs, torn speaker cloth, missing back).

This model has a wheel in the front for selecting stations with a little handle for quick selecting them (I assume). There are dozens of little windows that used to have station letters in them; they've all been punched out.

My biggest concern is that the thing was working (albeit with a loud hum). Then it stopped. My guess is that it's related to the power switch which rotates clockwise, off, on, bass. I was using tuner cleaner and it's nice and smooth now, but no power Icon_sad

I checked the cord. Power is getting to the chassis, but that's it. The chassis doesn't "light up" (tubes, that is).

Any help is appreciated.

Tony B. - Rochester, NY

- planigan - 05-22-2006

Tony sounds like the electrolytic caps went. When they are on there way out you get a lot of hum on the speaker because they are the filter caps in the rectifier circuit. Suggest you do not power the set on any more before you replace the electolytics, you may damage parts that can not be replaced. The newer electrolytics should meet or exceed the rated voltage on old caps or the schematic and can be a little higher in mfd then old ones jbut try to styay within 20% and on the plus side. These caps have polarity markings and you have to be careful to follow them or you will do considerable damage to them and the set. Since the new caps are about one fifth the size of the old ones they can be mounted under the chassis or in the old cans. Make sure you disconnect the old ones if you hang them under the chassis. Pat

- planigan - 05-22-2006

Tony: On those caps, there is a dual 8-10mfd and a 18mfd which could be replaced with a 10mfd, a 15mfd and a 20mfd respectively at 450V. I just got back from looking at schematic. PL

- planigan - 05-22-2006

PS: You also have a 1mfd - 3mfd which I missed on the first go round. I believe the latter can be lower voltages, check the old cans for voltage rating. You can get 1mfd and 3.3mfd at 450 volts also. On the voltages you can go as high as you want the only draw back is really overkill and money. By the way, the first three (10,8,18[2 cans]) should have insulating collars (cardboard wrap) on their base to keep them off the chassis ground. That becomes your B- for bias. Don't connect the negative leads of those capacitors to chassis gnd. You may have to add a small terminal strip under the chassis to hook them up correctly in the circuit. If you are going to stuff them in the cans, save that little terminal lugs that are fitted snugly between the can and the insulating collars. Cans are aluminum so instead of soldering the lugs to the can they are press against it by the insulators and thus make contact with can, they are sheet metal and wires can then be soldered to to them. PL

- Guest - 05-23-2006

Hi Pat:

I sent you an email diretly, but thought I'd post it here also, in case you missed it or should anyone else wish to chime in.

I'm a complete neophyte when it comes to the electronics in these things. I'm pretty handy with a soldering iron, though, so I'm sure I can handle the project if I know what I'm doing.

What exactly are the electrolytic caps and how do I go about getting replacements and changing them? The chassis doesn't look that complicated, but is there some direction you can steer me in as far as someone with no previous experience doing this himself?

Thanks.

- Terry Judkins - 05-23-2006

Phil's Antique Radio site has an excellent tutorial for the beginner. http://antiqueradio.org/begin.htm

- planigan - 05-24-2006

Tony, hi again. Good advice from Terry. I just got into this about two months ago myself. Going to the various sites including PhilcoRepairBench.com will give you a lot of information. So will this forum. Go through the previous months and drop in to see the problems presented and the solutions offered. Another good site is NostalgiaAir.net.
Electrolytics are most often capacitors (condensors) with a value over 1MFD. You will find that most capacitors used in the radio are below 1MFD, in fact usually tenths or hundreths of a MFD. They get their name from the fact that they use an electrolytic (fluid through which electricity can pass) which is the primary reason they fail, they dry up. They also have another unique feature which is they are polorized, that is they pass electricity in one direction and not the other. They are contained in those large aluminium tubes you see on the chassis. Note that some of the can type structures are not electrolytics but contain, usually, IF (intermidiate frequency [don't worry about this right now you don't have to know until you run into problems] transformers which have to do with the operation of the radio. If you want a more detailed description I suggest you visit faradnet.com and check in "about". That site will go so far as to inform you of the chemical /electrical reactions that take place in the caps.
I would suggest that you check out PhilcoRepairBench and order the schematic for your set from Chuck Schwark. You will get good quality, easy to read schemtic and other information (parts list, service bulletins and voltage chart) for a small cost. When I started out I paid for one that I down loaded and it was bearly readable, Chuck's look like he printed them for you. I bounce in and out of this site all the time. You will find that everyone is helpful and encouraging. On my set, a 37-650 Philco, it was not working when I got it and now after re-capping and re-resistoring, its still not working. But don't dispair, your was working when you started. If you take it slow, fix those electrolytics (that is a must) you may decide to replace the other caps which also go but thats because the technology back then wasn't as good as now and they do fail with age though not with the same devastating effects as the electrolytics. I've gone on too long. Keep me up to date, I'll give you what ever advice I can if it's within my knowledge (I'm pretty good at the mechanical aspects but not to hot on the theory of operation). Pat