My Simple Renewal For S-38's
Over the years, I suppose that many others have done much the same as I have, in restoring old S-38's to a new life, for many years to come. First thing I always do when I get another S-38, is cut the line cord off. Never power up an old radio without first taking a good long look at what's underneath. Next thing I always do is replace all the old tubular caps and filter caps. In the case above, an S-38C, I replaced 7 tubular caps, four filter caps, one resistor and re-wired the AC line and on/off switch as detailed in another location on this web site, something that I highly recommend. I'm not a purist when it comes to restoration, so making an improvement here and there is no problem.
The original filter cap is a large four section job. Even if your radio is now working, don't leave that original cap in there any longer. Replace it before it fails and causes other grief. It will fail!! I randomly checked one tubular cap I replaced and found that it had increased more than three times its stated value.
When I replaced the large filter cap, I clipped the original wires at the body of the cap and used those wires to attach to the terminal strip I installed to mount the new caps, seen at the lower left above. Inside the old electrolytic cap was a 20 mfd cap, rated at 25 volts. I used a 20 mfd at 160 volts for a replacement as that was what I had on hand at the time. It connect to the cathode of the 50L6 audio output tube.
After the parts replacement and re-wiring, I attached the radio to a line isolation transformer and Variac, then brought the voltage up slowly. First to about 30 volts, then in 10 volts steps until I got to 50 volts, where I let it sit for about an hour. At about 60 volts AC, the radio started coming alive. Amazing! Half voltage and I could tune BC stations easily. After seeing that nothing smoked, I brought the line voltage up to the full 120 volts and happily let it play along to make sure all was well. After making sure everything is ok, plan on doing a complete RF, IF and oscillator alignment. Since I'm not into doing painting at this point, I'm content to do the simple things. Clean the controls, chassis, tubes, speaker and case and remove any rust. Always check the chassis rubber isolators and install new ones if needed. If any knobs are broken or missing, old non-working radios can always be had on eBay, and use them as your parts store.
I hope you have as much fun as I do, bringing an old radio back to life and knowing that some future kid just might get their start with an S-38 that you worked on. Have fun!
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New Terminal Strip with the new Filters