Philco 37-640 - Printable Version
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Philco 37-640 - mikethedruid - 01-27-2020
Now that I am done with the RCA 5Q55, I am starting to tackle the Philco 37-640 you saw me post some pictures of in the January Finds and Losses thread. Those show the cabinet and exterior as it looked when I brought it home. Today I pulled the chassis out of the cabinet. I ordered a bunch of stuff from Renovated Radios. I bought all new knobs. Mine had the wrong knob for the band selector, and I want all the knobs to match. I'll just put the old ones in my box of knobs and save them in case I need therm someday. I also bought all new rubber parts, the tuner mounting rubbers, the front bumpers, and the chassis mount spacers. Looking at the underside of the chassis I realize what a blivit I have gotten myself into. You do know what a blivit is, don't you? 10 pounds of crap stuffed in a 5 pound sack. This chassis is going to be the worst I have tackled yet, makes the RCA 18T I did a while ago look easy. The wires are all so brittle I am going to have to replace them all just for safety's sake, and the components are all packed in close together. Do you ever curse yourself for this addiction that leads you into these things? I do. Oh well, nothing to be done about it but to get this old beast working again. I've already invested almost $100 in the parts I ordered today. Too late to back out now. Looking at the schematic, this radio should be a great performer once I get her done. Here are before pictures of the chassis.
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RE: Philco 37-640 - morzh - 01-27-2020
Yikers!
I rarely see chassis with so much dirt underneath. Top is another matter, it is often dirty or at least very dusty, but even in open type without bottom cover the underside usually is very clean.
This one is nasty.
You have lots of cleaning to do.
Where was it kept?
RE: Philco 37-640 - mikethedruid - 01-27-2020
I really don't know its history, Mike. The lady said she had to "get it up from here basement," when I picked it up, so I suppose it was down there. It shows a lot of signs of being somewhere damp, rust, etc. LOTS of dust too. Fortunately no rats nests, although mice or rats may be responsible for some of the rusting on the chassis top, I don't know. A lot of the top is rusty, the one remaining tube shield is very rusty, on all sides and even inside, so it may just be from damp exposure. If it was in an unheated basement or attic here in these mountains, it would have had a problem with damp and condensation. We get a lot of fog up here.
In other news, I began to tackle disassembly, taking apart the dial and associated components. I cleaned the dial, and it came out pretty well. It can definitely be re-used, which is good and will save me some money. I cleaned it using lighter fluid. It works as well as "mineral spirits," doing no damage to the lettering. It also evaporates very fast, being naphtha.
Question, has anyone encountered a felt washer or ring on the main tuning shaft between it and the dial shadow piece? Mine had something like that all around the shaft, grey, and it seemed to be a thick felt washer, although I wonder if it was just the dust of ages never cleaned out.
RE: Philco 37-640 - mikethedruid - 01-27-2020
I just read through Bob Andersen's thread on restoring his 37-640. He did a complete strip down, as I am going to have to do. What a wonderful help that thread is going to be! Thanks, Bob ! I have bookmarked the thread for easy reference. Here's a link to it: https://philcoradio.com/phorum/showthread.php?tid=12683&highlight=37-640
RE: Philco 37-640 - truePhilco - 01-27-2020
Have you test any of your coils yet?
I will be hoping they hold up to the volts for you.
RE: Philco 37-640 - mikethedruid - 01-28-2020
Actually, True, I have a 37-630 chassis I will be stripping for some parts, I need the electrolytic condensers from it since whoever worked on mine many years ago simply removed them and stuck tubular electrolytics under the chassis, making it even more crowded than it originally was, and that was PLENTY. This means I also have a complete set of extra coils, antenna, RF, and oscillator, since it uses the same coils as the 37-640. They are, for Antenna, BC = 32-2108, PB = 32-2119, and SW = 32-2109; for RF, BC = 32-2105, PB = 32-2106, and SW = 32-2126; for Osc, BC = 32-2120, PB = 32-2121, and SW = 32-2110. It also seems to use the exact same dial and dial masking parts; and, the more I look at it, I begin to believe that the whole tuning sub assembly is actually the same. This is very good news as the parts chassis is in much better condition, and so the coils will probably be good in case I need to replace the ones in the 37-640. Upon further examination and study, if they ARE the same, I will use the tuning sub assembly from the parts chassis, and not the one that is in the 37-640 presently.
RE: Philco 37-640 - mikethedruid - 01-30-2020
I looked at the schematic for the 37-630 from the library here, copied the PDF of the service documents. I compared it to the schematic I printed out for the 37-640, which is also from the library here. From what I can see the two tuning sections are IDENTICAL. Most of the part reference numbers are even the same, as if someone did a copy and paste when they made the 640 schematic, more likely a tracing back in those days. Just to be sure, can anyone else verify this as a fact? Do any of the real experts on these models here either know if they are exactly the same, or are their differences I missed? I have pulled the tuning section from the 37-630 chassis I am stripping for parts already, and from all I can see, I can use it instead of the NASTY one. It is MUCH cleaner underneath, and will be a much easier job to rebuild, with a much better chance of success.
In other news, this tuning section also had a thick felt washer around the tuning shaft, one in MUCH better condition, so I now have an answer to that question, and a good felt washer to use when I reassemble the tuning section.
RE: Philco 37-640 - mikethedruid - 01-31-2020
First, a thank you to Ron for his wonderful, well illustrated, and informative thread on how he restored a 37-640. It is going to be of GREAT help. Tonight I began to work on the tuning section. What an almighty BLIVIT ! I have the front and middle plates removed and wires and caps replaced, as well as the 2 resistors on the front plate which were WAY over tolerance. Thankfully the mica caps are OK, and I don't have to replace those, which would mean even more intricate surgery than I really want to do. That just leaves the rear plate, which won't be too bad. The front plate is the worst.
RE: Philco 37-640 - mikethedruid - 02-01-2020
All the plates are now rebuilt, and the tuning assembly is back together. What a pain in the a**! I had marked ALL the wires I disconnected from the original tuning section, but some of the labels fell off, what fun ! I don't think it will be TOO much of a problem as long as I trace everything out from the schematic, it will just take more time.
I have received my rubber parts and a set of knobs from Renovated Radios, which is good. Now, on to the rest of the chassis. After the tuning section that will not be as bad... I hope.
RE: Philco 37-640 - mikethedruid - 02-02-2020
Today I started on the IF section of the chassis. I'm about half way through it now. Interestingly, the resistors in this section seem to have stayed in tolerance much better than the ones in the tuning section., so I have left them be. There's enough with replacing all the paper condensers. The mica condensers are also well in tolerance. This section is a lot easier than the tuning section, although things are still stuffed in. I don't think Philco really intended that these radios would be rebuilt eighty years after they were made. I don't think they even imagined that they would be considered collectors items.
RE: Philco 37-640 - mikethedruid - 02-03-2020
Time for some pictures. I finished with the IF section. Power and amp end is all that is left. I rebuilt the electrolytic can, replaced all the paper caps. The resistors all are within spec, and, since they are kind of a pain to remove, I left them, as I did with the mica caps which were also OK. I like my cap tested, VERY useful addition to my test equipment.
The IF section all done...
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The tuning section all done...
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RE: Philco 37-640 - Jake Blake - 02-04-2020
Nice pics Mike....thanks for sharing!
RE: Philco 37-640 - mikethedruid - 02-04-2020
I have come to a dilemma, and hope those more expert than I, who have dealt with this model radio can give me some guidance. As I am delving into the power - final audio end of the receiver, I am making a careful map of everything, and where it goes, and where it connects. In doing so I have come to a problem about part 51. On the schematic, and in the parts list it is shown to be a 70K resistor, yet in the radio itself it appears to be a 10K resistor, and it appears to be original and never changed. Was this a mistake in construction, or a change made along the way which I haven't seen in the notes? What was it in your own 37-640s? I would appreciate any advice about this. Here are pertinent pictures...
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RE: Philco 37-640 - Steve Davis - 02-04-2020
The body of that resistor looks violet to me. Pretty sure it is a 70K.
Steve
RE: Philco 37-640 - mikethedruid - 02-05-2020
It looked brown body to me. I measured it, and it came in a little over 85K. Upon cleaning it some, I could see traces of violet on the body. Guess you have better eyes than I do. I am not colorblind, but sometimes I don't see them as vividly as most people. Anyway, that question is solved. Thanks, Steve !