Model 37-116X Project - Printable Version
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Model 37-116X Project - Chris h - 10-23-2016
Hello all,
I am working my way through my 37-116X, slowly going through the electronic restoration. I have replaced all the wax/paper caps and OT resistors in the power unit, and most of the IF unit. I have powered up and the radio is operating, as I replace a little and check, as I go. I really didn't want to dig into the RF chassis, but it must be done. I have now removed the RF sub-chassis, and am replacing what wax/paper caps that I can get to. Those that I have replaced have been very leaky, as measured on my Tel-Ohmike. There are two caps that are really buried within the band switch. I am scratching my head, trying to figure out how to go about replacing them. I am afraid to move too much around, afraid of breaking something, or causing more damages. Any tips or tricks as to how to go about replacing those two down in the band switch? I was thinking of some how attaching the switch contact end at another location, and mounting the caps outside the switch some how. But, so far, have not found a way to get into them. I have two chassis at my disposal, but would rather not have to dig into the other one to salvage parts if I don't need to. I am wondering just how important it is to replace these caps. I am thinking, since it works, maybe I should let sleeping dogs lie? This radio is for me, and not for someone else. Nor do I intend to sell.
Thanks for looking.
RE: Model 37-116X Project - morzh - 10-23-2016
Chris
Best advice I can come up with is use cutters, cut the caps off. Do not desolder. Then replace. I was able to replace mine without removing the RF chassis but that was a pain and required some creative thinking.
RE: Model 37-116X Project - Radioroslyn - 10-23-2016
I did one back in the 80's and didn't pull the rf deck. Worked great for a year or so and in died. After troubleshoot it i found a paper cap in the rf deck was very leaky and had killed off the hv to the oscillator section.
Was able to remove and replace it but was a pita.
RE: Model 37-116X Project - Chris h - 10-24-2016
Thanks for the replies. I had pretty much figured that I would not be desoldering the old caps at their connection points. I was planning to leave in place and simply cut the chassis grounds, which I can reach. I can see the switch connection points, but can't get to them without removing something. Was thinking of removing the row of trimmer caps to gain access. And then getting in there with the soldering iron to tack the new ones in place. I am just fearful of causing more damage.
I was afraid if I left them in the circuit I may have more problems later on, so not replacing them is not a good option.
I have taken lots of photos and taken a lot of notes to get the lead dress back to their proper locations when removing the chassis. I don't know how you did it without removing the sub chassis. Must have been a real challenge!
I was just wondering if any of you had noticed poor build quality on these chassis. I am sure they must have been a real PIA to build to begin with, but I am seeing big solder blobs and other questionable practices on this unit. Maybe it was built on a Monday? It doesn't appear that someone has been into the subchassis before.
I'll keep plugging at it, and take my time. Thanks for the advise.
RE: Model 37-116X Project - Kenneth F. Besso Jr. - 10-24-2016
There was a video on you tube how to do this,,,,he would de-solder ,,the end he could work on,,,close to the side you are on,,,he would twist the capacitor,,,by the body itself,,,real easy ,,from clockwise to cc wise,,till the cap pulled off the wire lead,,,,,Then ,,he wound ,,wrap the New lead around something to make a pig tail-(preferable on a paperclip to get the form))),,,and THEN,,,slide it onto the old capacitor lead,,,you know the rest of the Drill,solder----Cheers
RE: Model 37-116X Project - Chris h - 10-24-2016
The problem with these particular caps is that they are really buried within the band switch. The other wax/paper caps in the RF chassis are relatively easy to get to, once the chassis is removed. There was one where I resorted to the "twist until it breaks" method and was able to splice the new cap in place. These were relatively easy, as compared to the two within the switch, itself. These are caps #9 (connected to B3 on the wafer switch), and cap #28 (on terminal E3 of the wafer switch). These guys are really buried and almost invisible from all angles, even with the chassis and side plates removed.
Well, I was able to replace the caps by, carefully, cutting off the rivets holding both 3-gang trimmer caps that are attached to the divider plates separating the 3 sections of the chassis. I disconnected the trimmers from the coils and removed them completely from the chassis. I used a small rotary file in the Dramel tool to cut the heads off the rivets, and was careful that the chips fell outside the chassis.
I placed a long length of spaghetti tubing on the new cap lead, and formed a hook on the end, carefully wrapping the lead around the switch terminal as best I could and carefully soldered in place. I positioned the new cap outside of the band switch. Then cut off the chassis ground lead from the old cap as close as I could cut it off. (I just left the old caps in place. I could see no means of removing them without damaging something.) I attached the chassis ground lead, with a length of spaghetti tubing, to the same chassis terminal as where the old cap lead was attached.
I reattached the 3-gang trimmer caps to the original mounting position on the dividers with #4-40 fasteners and lock washers. Then re-attached the coil and switch leads to the trimmers. It was really not as bad as I thought it was going to be. I have yet to reinstall the chassis, as I am waiting on new cloth insulated wire to replace the chassis leads to the main chassis. Some of these leads can be reattached through holes in the top side of the sub-chassis, under the tuning cap. Some are relatively easy to get to from the sides, and some will just have to be spliced, as they are just not in a position to get to.
The big question is, is it going to work afterwards???? I usually replace one or two components at a time, and test, just to make sure I have not flubbed up somewhere, but in this case, that is not an option. Hopefully this may help someone else out when they go through the same thing. It may not be the right way, but it is the method that worked for me.
Thanks for the advice.
RE: Model 37-116X Project - k9uw - 10-31-2016
Chris, take a look at this link for a method for accessing those buried caps. Using this method avoids the exhaustive means of disassembly described by others.
http://johnjeanantiqueradio.com/philco.htm
My sincere thanks to go John, K9UWA, for devising and posting this technique. I've used it on several sets with no surprises. It looks intimidating, and the intimidation caused me to put my 37-11 on the shelf for a month or so. Once I got started, though, the process was straightforward. If I, as a registered Klutz, was able to do it then you will surely succeed. Read the instructions several times and note the advice specific to the 37-116. Create enough space to work and you'll be fine.
RE: Model 37-116X Project - Chris h - 11-01-2016
Hi Mike,
I thought there might be a better way. But too late for me now. I have already removed and replaced the sub-chassis. Many of the interconnecting wires needed replacement anyway. (That's what I am telling myself, anyway.) It really wasn't that bad, to be honest. I just marked every lead and noted where they were connected. The only hiccup was that I missed one lead location on my location map. I still think removing the sub-chassis was a good option. Removing it takes the stress off the leads when manipulating the chassis. Especially when trying to get to those two caps buried inside the band switch.
Long story short; I powered it up last night. It all appears to be working, on the BC band, anyway. I still have more to do, but at least it is working.
One of the more difficult areas, I thought, was in the audio section, immediately behind the sub-chassis, on the main chassis. Getting to and replacing some of those caps and resistors was somewhat difficult. I found one resistor in the volume control circuit (as I recall) that I couldn't find on the schematic, parts locator, or parts list. It was a 2 meg, and appeared to be factory installed. Since it was within spec I decided not to replace it and left in place. I need to go thru the change list and see if it is mentioned there.
All in all, I am just pleased that it is what appears to be working normally. The AFC is even working.
Thanks again.
RE: Model 37-116X Project - Chris h - 11-08-2016
Well, progress was made, last night. The radio has been working since the reinstalling of the sub chassis, but the audio, while strong, was distorted somewhat. I have been going thru the chassis checking tube voltages and found the voltages of the 1st audio was WAY OFF. The plate voltage was only 26 volts, should be around 90, as I recall. With the tube pulled, I was getting around 220 volts on the plate pins, so it had to be somewhere in the voltage supply to the plate or grid circuit. Everything checked out in the plate supply. The grid circuit, with no voltages listed, was a little more difficult. I lifted the grid lead and the plate voltage came up a little. Tracing the grid voltage back to it's source revealed a misswire. It was grounded! Put back in it's proper point brought the 1st audio plate back up where it should be, and the distortion went away! I just figured that I had miss wired the connection when restuffing the Bakelite block to which it was connected, but I was not guilty in this case. After taking a look at the under chassis photos that I took, before starting this project, revealed that the lead was miss connected when I started! Either from a previous repairman or from the factory, who knows? From the photo, it looked as if it had been unmolested.
Anyway, it is playing beautifully now. Now on to cleaning up and installing the tuning dial before starting on alignment. The magnetic tuning appears to be working, somewhat, on strong signals, anyway. I don't know what to expect. Having never seen this feature before. All you have to do is come close, and it brings the station in, but usually needs a little fine tuning. Maybe after alignment it will be a little better? As said, I don't know how well this worked from new.
RE: Model 37-116X Project - klondike98 - 11-08-2016
Good work!!!
RE: Model 37-116X Project - Chris h - 11-08-2016
One thing I have run into is the first short wave band is dead. (Sorry, but don't know the frequency coverage, off the top of my head.) I have been attributing this to a poor antenna in my shop. I am not even getting static on this band. I haven't been too concerned about it, due to the poor antenna, but I noticed last night that the RF chassis is microphonic on this band, at times. I do get signals on the 2nd SW band. No signals on the 3rd. but do get static. I have applied very small amounts of Deoxit to the band switch contacts with the needle applicator, but not much else. I have not checked the oscillator for operation on this dead band yet. I suspect it is not operating.
Any ideas as to where to look?
Thanks in advance.
RE: Model 37-116X Project - 462ron - 11-08-2016
Chris, the band #2, which is the first sw band is known to have an open oscillator coil in this chassis. Not at an easy item to find. Took me 3 tries to rewind it and it works but the frequencies are way off on mine!
Ron
RE: Model 37-116X Project - Chris h - 11-09-2016
Thanks Ron. I was afraid of something like an open coil! And I just buttoned up the sub-chassis. Next time I have time to work on it, I will bring down another receiver and see if I can pick up the oscillator on that band. The scope couldn't see it, so it probably wasn't working, but will see what, if anything, I can hear. I do have another donner chassis from which I can extract another coil, if it isn't bad too. Or I may just leave it. I like for my radios to be in working condition, but in all honesty, probably won't use it on the short wave bands anyway. With these things it's always something! But that's what it's all about. If it was easy, anyone could do it!
RE: Model 37-116X Project - 462ron - 11-09-2016
Chris I don't think there is much on that first sw band anyway!
Ron
RE: Model 37-116X Project - Chris h - 11-15-2016
I am now starting on the tuning dial mechanism. The first thing I need to deal with is the flexible shaft coupling. The flexing element looks like it might be leather? It is hard and stiff. I am concerned that in this condition, tuning may not be smooth. Any ideas for softening this up would be appreciated. Or should I be looking for a replacement or even rebuilding?
The rest of the mechanism appears to be in good shape. The dial face has some wear in places where it has been rubbing the bezzel. I understand that new repop dials are not available right now. (At least the original looking ones.) So I can live with what I have for now, anyway.
I still need to rewire the lamp sockets, and install a fuse in the power supply. I am planning to install a dropping resistor to drop the line voltage to something closer to 115 vac, unless someone has a better suggestion. A thermistor for inrush protection, maybe?
Thanks for all the advise.