[k9uw]

I'm working on a 38-116 and have it playing nicely.  The Magnetic Tuning switch has failed in the "On" position, however and I'm exploring options to replace it.  The switch won't move to the "off" position.  The part number is 42-1216 and it appears in the schematic as part #96.

   


I have a 37-11 parts chassis that includes a magnetic tuning switch which is identified as Philco Part number 42-1269 and it appears on the 37-11's schematic as #17

   

These switches appear to be functionally identical to my somewhat inexperienced eyes and I'm thinking that the difference in part numbers might be explained by the shaft lengths with the 38-116's being longer.  to deal with the thicker cabinet.  The difference in shaft lengths would be fairly easy to overcome with a coupler, at least that is what I'm thinking of doing.

Maybe I should leave the broken switch as it is since it is in the "on" position?  Your suggestions and insights would be appreciated.

[Radioroslyn]

I'd switch em.

[Arran]

By failing in the "On" position do you mean that the shaft is seized or that it is free but the magnetic tuning will not turn off? If it is seized I would squirt some penetrating oil on the shaft bushing letting it soak for a while, and maybe apply a little heat too like from a soldering iron, and see if that frees it up.
 If it is really bad I would think about removing the switch and taking it apart to clean the hardened grease or rust out of it. Usually these have a "C" clip on the shaft just in front of the bushing which holds the shaft in place, if you remove that then you can get the shaft assembly out through the rear, that is if it's a normal rotary switch. 
Regards
Arran

[k9uw]

The switch worked initially and produced a decisive "click" as it moved between positions.  Now, the shaft rotates a few degrees but it refuses to move into the "other" position.  I assume that it is stuck in the "on" position because the switch activates two dial lamps in the "on" position and those lamps are lit.  At least that is how I interpret the schematic, and that is how the switch functions on the 37-11.  

Your suggestions for freeing the switch are appreciated.  I'll give those ideas a try and will report back, perhaps with photos as well.

Odd - the images of the schematic inserted into my original post do not show up for me when I view my own post.  When replying, however, they show up.  Anyone know why that would be?  I've tried 3 different browsers and the inserted images did not appear in any of them.

[klondike98]

Odd - the images of the schematic inserted into my original post do not show up for me when I view my own post.  When replying, however, they show up.  Anyone know why that would be?  I've tried 3 different browsers and the inserted images did not appear in any of them.

Mike, thanks for pointing out that image issue. I don't know if its related to the new MyBB software upgrade or not but will let Ron know and perhaps we can sort it out. (I can see the the two small images in your original post.)

[Ron Ramirez]

...I see them as well...

I will be looking for a MyBB mod that will allow people to post pictures of any size and that will automatically shrink them to a size usable in the Phorum, but I'm tied up this afternoon and evening...

[klondike98]

Mike,
Ron looked at the MyBB settings and does not see anything obvious causing you to not see the attaced photos.  Not being logged in will cause it but you must be logged in if you are replying to a post.

Can you see the photos in the first post of this thread by OldRestorer?  http://philcoradio.com/phorum/showthread.php?tid=15993

[k9uw]

Yes, I can. Oh, well, as long as you guys are able to see what I posted, my need is fulfilled.

[Nick3092]

Yes, I can.  Oh, well, as long as you guys are able to see what I posted, my need is fulfilled.

You might be able to fix the broken switch. I have a 37-116 where the magnetic tuning would not turn off/on. I found that there was an "L" shaped part that was supposed to sit in a "U" shaped part. One side of the "U" had bent over. So the bottom of the "L" would glide right over it without changing the switch position. I was able to bend it back up and lubed it well to hopefully prevent any physical resistance that would lead to it bending back again. I don't flip that switch on and off very often, but so far it's held up about 2 years now. 

This post of mine shows what I'm talking about:
http://www.philcoradio.com/phorum/showth...4#pid76574

[Phlogiston]

It is very common for these switches to be intermittent on one or both sides - even when they do "click". An original part used as a replacement has a good chance of going bad. I recall fighting this issue many times, I just cant remember what I did to fix it. Probably best to try to disassemble one of the switches an attempt a repair.

One side of the switch activates the display bulbs, the other side turns on the magnetic tuning feature.

[k9uw]

Finally got some time to examine the bad switch and discovered that the reason for the "failure" was due to the loss of the ball bearing that provided the detent action. The switch shaft rotates a few degrees, enough to move the contact from "Off" to "On", but there is no feedback that the switch has moved the required amount.

Fortunately, the missing bearing was located on the bench. Unfortunately, I dropped it in the radio on the 7th attempt to reinstall it and it got by my protective cover that had caught it after each of the previous attempts. After 30 minutes of searching the bowels of the chassis I cannot find it anywhere. I had pulled the switch from its mounting hole but it was still connected to its wires. Hopefully the missing bearing won't short something.....my hand still stings from repeatedly slapping my forehead.

Wish I could roll back the clock a few hours but retain the memory of what happened! I also wish I knew why the bearing dropped out of the switch in the first place. The retaining clip seems springy enough.

Anyone know what size that bearing was? 3/32", maybe? I'm going to visit my regional hardware store tomorrow.

[k9uw]

As Phlogiston pointed out, this control has two switches. One switch is exposed on a wafer and controls the AFC circuit while the other is inside a plastic or Bakelite enclosure and controls the two dial lamps on either side of the magnetic tuning dial. The dial lamp switch was defective and a previous repair had simply shorted the switch so the dial lamps were always lit when the radio was on.

The replacement switch came from a 37-10 parts chassis and, aside from a too-short shaft, seems identical to the original and is working perfectly. A shaft coupler from the local hardware store will enable me to correct that short shaft problem.

In case anyone else has to replace the missing ball bearing that makes the detent work correctly, please know that a BB (copper coated steel) is the right size and seems to be working perfectly.

Sorry for the late update, but this information might be useful to others in the future. My thanks to Ron and anyone else who makes this phorum available