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37-630 Intermittent issue - solved - Printable Version

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37-630 Intermittent issue - solved - PAradiogeek - 12-22-2016

I restored this radio about 2 years ago.  Over the past 6 months or so, I started noticing that after the radio was played for more than 30 minutes or so, all sound would sometimes cut out.  This didn't happen every time, but seemed to happen more and more as time progressed.  When this would happen, I found that giving the cabinet or the chassis a gentle rap would restore the sound.  It finally got bad enough that I decided to take a look underneath, assuming I had a bad solder connection somewhere.

Well I took it downstairs a few nights ago and played it (in cabinet) for almost 2 hours - played perfectly Icon_mad

The next night, removed the chassis from the cabinet, turned it upside down and turned it on again.  I started probing around with a plastic stick, touching wires and solder joints. - played perfectly Icon_mad Icon_mad .  After a couple of hours, I gave up for the evening.

So last night, I decided to give it another try.  I turned it on and started probing around again, still no luck.  Icon_mad Icon_mad Icon_mad

Then for no particular reason, I decided to take a look at the shadow meter, not because I suspected it was the problem, I just wanted to look at the deflection of the vane.  The shadow meter had been connected, but strewn off to the side while I had been probing in the chassis.  As soon as I started to move the shadow meter the sound cut out, just like it had been doing over the last several months.  I put it back where it had been, sound again Icon_biggrin

There seems to be an intermittent right were one of the wires from the chassis goes into the coil.  I used some glue that I had to try to hold the wire in place, thinking of adding some JB Weld to that to make a more stable fix.  Does that sound like a workable solution?

Anyway, I just wanted to post this in case anyone else ever had a similar problem.  I knew the shadow meter was required for operation, but I had never suspected it as the source of the intermittent.  Moral of the story: Check EVERYTHING!

Happy Holidays!

RE: 37-630 Intermittent issue - solved - morzh - 12-22-2016

In many Philcos the Shadowmeter is bypassed with 2-3K resistor, so when the shadowmeter quits the radio still plays.

RE: 37-630 Intermittent issue - solved - PAradiogeek - 12-22-2016

Thanks Morzh,

Can a bypass resistor be added if it wasn't in the original? If so, how do you size it in terms of ohms? The SM in my set measures 1400 ohms on a DVM.

RE: 37-630 Intermittent issue - solved - Radioroslyn - 12-22-2016

(12-22-2016, 04:36 PM)morzh Wrote:  In many Philcos the Shadowmeter is bypassed with 2-3K resistor, so when the shadowmeter quits the radio still plays.

Hi Jon,
How tricks up in north Montco???
Took a quick look at the 37-630 schematic but I don't see a resistor across the shadow meter as Mike describes. My older 660 does have one. You could disconnect the sm and use a 1k or 1.5k 1/2w resistor in it's place. If that clears up the problem you'll need to rewind your sm coil. You could also monitor the hv at the bottom of the 1st IF transformer as the sm feeds it. If you see the voltage fluctuating a lot it's time to rewind. I suppose there could be an issue with the sm coil heating slightly from it's normal operation. THis might cause a sm break in the coil where it's warm.

RE: 37-630 Intermittent issue - solved - Ron Ramirez - 12-22-2016

DO NOT use J-B Weld on that shadowmeter. It is conductive.

RE: 37-630 Intermittent issue - solved - Radioroslyn - 12-22-2016

(12-22-2016, 05:11 PM)Ron Ramirez Wrote:  DO NOT use J-B Weld on that shadowmeter. It is conductive.

Sounds exciting!!!!!!!!!
Maybe you won't really need that resistor!

RE: 37-630 Intermittent issue - solved - morzh - 12-22-2016

In the model 660 it is a 2K resistor.
In the 37-116 it is 1K.
The less the resistance for the given meter the narrower the segment will become.

RE: 37-630 Intermittent issue - solved - PAradiogeek - 12-22-2016

Thanks Ron! Glad I asked before just putting it on. Do you know of an appropriate glue that I could use? My first thought was hot glue, but I figured things might get warm if the radio is running for a few hours and I wouldn't want that stuff running down onto the chassis.

Thank you also Terry. Things are going well, trying to get ready for Christmas. We usually play Christmas music on this radio during the day on Christmas, so I wanted to get it ready. Uggghh, I hope I don't have to rewind that coil, but I realize that may be the only permanent solution. How have you been?

Morzh: "Maybe you won't really need that resistor! " Too funny.

RE: 37-630 Intermittent issue - solved - Radioroslyn - 12-22-2016

> How have you been?
So old rotten self!!!
Tnx for asking.

RE: 37-630 Intermittent issue - solved - morzh - 12-22-2016

(12-22-2016, 08:26 PM)PAradiogeek Wrote:  Thanks Ron!  Glad I asked before just putting it on.  Do you know of an appropriate glue that I could use?  My first thought was hot glue, but I figured things might get warm if the radio is running for a few hours and I wouldn't want that stuff running down onto the chassis.

Thank you also Terry.  Things are going well, trying to get ready for Christmas.  We usually play Christmas music on this radio during the day on Christmas, so I wanted to get it ready.  Uggghh, I hope I don't have to rewind that coil, but I realize that may be the only permanent solution.  How have you been?

Morzh: "Maybe you won't really need that resistor! " Too funny.

That's not me, that's Terry.

RE: 37-630 Intermittent issue - solved - Ron Ramirez - 12-22-2016

(12-22-2016, 08:26 PM)PAradiogeek Wrote:  Do you know of an appropriate glue that I could use?

Clear epoxy.

RE: 37-630 Intermittent issue - solved - PAradiogeek - 12-23-2016

Thanks Ron,

Ditto Morzh for setting me straight.

Sorry Terry. I somehow misread that and didn't notice it was you.

RE: 37-630 Intermittent issue - solved - TV MAN - 12-23-2016

Gotta love those intermittent problems! These type of problems seem to follow me for some reason. Had a bunch of those when I was in electronics professionally. I had my model 70 fail recently - intermittent also. Will start a new thread on that later when I decide to tackle it. Clear silicone (or any color Icon_e_smile ) would work to hold your SM wires. Anyway, glad you found it.

RE: 37-630 Intermittent issue - solved - morzh - 12-23-2016

What worries me about the silicone that is sold in stores, it really reeks of vinegar and from what i read it is for a reason - it does either exude acetic acid when curing or something to that effect.
Acid could damage wires.

Maybe it's an empty scare but I do not like acid smell near copper wiring.

RE: 37-630 Intermittent issue - solved - KCMike - 12-23-2016

You could maybe use something like this. Little pricey though.
https://www.amazon.com/3M-Scotch-Weld-Epoxy-Potting-Compound/dp/B000X5G6O6