[tbone]

Well I finally had time to start restoring my prize. It did work and all functions and bands were good to start which is a blessing.

There are a lot of issues with this radio as someone did a mediocre job and just replaced caps. I found many bad resistors, one cap missed in the sub chassis, the bypass cap can was never replaced with new caps, and lots of poor solder connections.

So far I have rebuilt the Power Supply/Amp chassis. All but one filter can were re-stuffed with 630V film caps. The biggest one would not fit inside the 18 uF can so it is under the chassis. The chassis had to be repainted because there was too much rust for my liking. I tested the chassis with the radio before I moved on to the rest so I would not have it to worry about unknown problems later on.

The sub chassis has been removed and stripped down for painting. I have changed all of the bad components already. Before I did this, I took pictures of how the dial assembly came apart and wrote a tutorial so I can put it together working backwards from my notes.

I also have the main chassis ready for painting. I haven't done much electronically with it yet, except to rebuild the lamp sockets, repair the on/off switch, and re-stuff the can cap with 630V film units.

I'm taking my time and marking off what I've done on the schematic. Also, there are notes about anything I found suspicious from the last guy.  

Here are some pictures of the process so far. I know there will be some questions I will need answered as I progress.

https://www.flickr.com/photos/152428891@...ed-public/

[morzh]

Good.

And you seem to have a good speaker.

Have you checked your interstage and the output transformers?

[tbone]

I got lucky with this one. All the active speakers have been reconed and the radio played before I started. It didn't have any Philco paper caps, so no restuffing there.
It's going to take time on the audio/detector side of the chassis as the components are packed tight.

[morzh]

Well.....38-690 is not as tight as it seems at the first glance. Compared to the 37-116 it is much easier. Especially the RF chassis, it is quite a bit easier.

[tbone]

Well I am pretty close to finishing the electronic restoration on both the amp/power supply and radio main chassis. I am going to ohm out my coils again since I was in all of them at one point, and also ohm out each B+ buss to make sure I have no shorts or surprises. I like to do this before power up.

I have a question about the audio shorting switch (74) on the tuning shaft. What is it's purpose, and how is it supposed to work physically? I have put it back the way it was found, but it appears to be shorted to ground intermittently where it rubs on the auto tuning collar. The contact that passes through the flat part of the shaft is not shorted, so that's good. My thoughts are that this switch is supposed to mute the audio while using the automatic tuning. Originally my radio had intermittent audio when manually tuned, which falls in line with what I am seeing now (intermittent short).

The schematic lists service bulletin 273 with reference to parts 6 and 16. The literature I received from Chuck did not have bulletin 273.

I appreciate your help in determining what I need to do in order to get this switch working properly. Attached is the schematic and picture of the questioned contact.

Thanks for your time.

https://www.flickr.com/photos/152428891@...ed-public/

http://www.nostalgiaair.org/pagesbymodel...013255.pdf

[Radioroslyn]

>I have a question about the audio shorting switch (74) on the tuning shaft. What is it's purpose

It's there so when you push in the crank on the front and use the auto tune feature it mutes the audio so you don't hear the stations as you tune.

Good Job!

[tbone]

Thanks for the confirmation Terry. Based on the picture I posted, what do you think I should do with the contact? The auto tune collar does not move in or out much from what I see to make and break. Is there something I'm missing?

[morzh]

OK.


The contact goes first over the shaft, you will see an insulator around it where the ring of contact goes over. Hen the fibre gasket with a tab on it goes over the contact so the tab with two sides cover part of the contact leaf. That makes the gasket rotate with the contact.
Then the part with the handle goes over. The handle should be behing the pin sticking out of that part, and both handle and the pin aligne with the contact.

There is a paper sleeve in that part's groove and the contact has to go in it. Yours is not. There is also second contact inside. This sleeve is to keep the contact rotating with the handle.

If the paper is missing or damaged the contact won't work properly.

See the document about the automated tuning. It is a bit intimidating but eventually very good.

[tbone]

Thanks Morzh,

The article you mentioned, would that be the one that comes with the service manual documents? If so, I have that and will read it. If it is something else, please point me in the right direction and I'll have at it.

As for the missing parts, the contact and insulating sleeve are present in the groove in the shaft, and they are working as I think they should, no shorts. My issue is the outer contact and the fact that it rubs on the auto tune lever assembly. The fiber washer is over the contact and working as the outer auto tune assembly doesn't short there either. Just the tip of the outer contact is the issue. A picture of that would help, but that may not be possible.

The good news is that the after surgery power up was successful. All bands and controls work as the should. About a 1.8 amp draw on the AC mains. A big load off my shoulders after all of the hours spent replacing caps, resistors, bad wires, and re-stuffing cans.

[morzh]

Yes this is the article.



   

The contact I have is bent a bit too much but you get an idea. The handle you press has been removed to not block the view.

[tbone]

Thank you for the picture, I will spend some time with it next week. Time for bed now. Nothing good ever comes from working on something when you're tired.

[tbone]

I took a quick look this morning, comparing my radio to the picture, and everything is there. I did not realize that there was a hidden contact on the auto tune collar and the insulating paper was there too. I'll have to align it so that everything works correctly, but that should be no problem.

Thanks again!

[morzh]

Do you know where these two rubber sleeves go when assembling everything back together?

I bought mibe over 2 years ago and took it apart at the seller's before going back home, so it's been some time since and  forgot.

   

[KCMike]

Mike is that the front rubber mounts that go on the chassis as in the fourth picture in this thread?
http://www.antiqueradios.com/forums/view...p?t=162923

[morzh]

Mike,

thanks for answering; no, doesn't seem so. I have those mounts, they are still on the front pins; they are much larger and thicker than mine. Mine are very soft and the tube sticking out of the disk is thin and very soft. The disk diameter is less than 3/4".
I am not sure whether they are original (way too pliable and seem to be silicon), but they were in the bag with everything else, and I put everything there myself when disassembling it.