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Dial strings and what-nots

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Dial strings and what-nots Empty Dial strings and what-nots

Post by DancingBear on Fri Jan 25, 2013 11:27 pm

I’ve been back into “repair” of old radios for about six months. I’ve worked slowly on the few radios I have on my bench so I could bring myself back up to speed. It’s been rewarding as far as the theory and the hands-on but the re-assembly portion has been a lesson in humility. I’m trying to get going after a few bad years fighting a doctor-induced infection in my hip. After all the med’s it seems my brain doesn’t pick up things like it used to.

When I began working on the ZenithS547, the first up to bat, I approached it like I would a repair in the past. I’ve done a lot of bench time so have good tool-skills and troubleshooting techniques but this isn’t all troubleshooting. There is a big difference between repair and restoration but it took awhile before I realized it. I’ve taken a break for about a week to re-group and find a good forum. My brain is hard-wired to get the unit back to the customer. (it’s a hobby for me…not income)

When I began I thought I could get out of the chassis refurbish without any big problems. The xfrmr was good, I pulled the rectifier, put in a solid state device and I gathered and replaced almost all of the capacitors. There were a few resistors that needed help so I replaced these. I began to wrap up so I could flip the chassis and maybe hook it up to the Variac. That’s when things began to fall apart.

The sockets went bad, one at a time, even though I was careful. I replaced a group of three and in doing all this began an analysis of the remaining resistors. It seemed that once I ran the Variac up to about forty volts the resistor values began drifting upward. I have now done the complete swap and I’m ready to turn it on again…but what else do I have to look forward to?

This isn’t a “repair”, it’s “restoration” and the difference is big. If I could do it over again I’d pull the sockets (except IF’s) and then run down the parts lists and order anything and everything that looks valid and gut the thing. I’d be way ahead. I haven’t gotten far on any of the others so ask for opinions on what I’m saying and help foreseeing future hassles.

What other concerns should I be aware of? To me, the most important thing to protect is the dial string as they are hard to rewind but now I’m concerned about the future of this bio-degradable string material and other parts. I replaced most of the cloth wire and ran sleeves over the delicately placed ones. How about the coils? Will the insulation between windings fall apart? I can epoxy some but others..??? How about the volume control/switch? To me they all look good...just like the sockets did.

Before I consider this unit in the “turn on and final” status what else should I look at? To me, the dial string strength is sufficient. Am I wrong?

I've gone through several check-lists from here and elsewhere. Things seem to be good so they get checked off only to fool me later.

Tony
DancingBear
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Post by jtauser on Sun Feb 24, 2013 1:45 am

If the dial cord isn't broken it's probably fine. If you do ever have to replace dial cord, I've found that 35 pound braided poly catfish line from Bass Pro shop is about the same diameter and works really well. You get a huge roll for less than $10. It comes in a tan color, but that is easily changed to the black color of dial cord by laying it on your bench on a piece of paper and coloring it with a fat-tipped Sharpie.

Another dial cord tip - a lot of them came with a little ring on the end that made them much easier to attach to the spring and the little hook on the tuning cap pulley. I found these rings with a setting tool at a craft or hobby store where they sell parts for making women's bracelets.

Joe T.
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Post by DancingBear on Sun Feb 24, 2013 10:46 am

Thanks, Joe. Good info. Chased a few bass in my time. Any excuse to look at fishing gear...
I don't fear the dial strings as much as I did before. The one great new tool of the digital age is the instant camera. When I began this project I made a promise to myself to take pix at every possible angle and perspective. It has been an immense payoff.

TonyM
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