Author Topic: The old GE radio  (Read 5134 times)

TC Chris

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The old GE radio
« on: January 15, 2019, 11:38:14 PM »
The GE E-86 console radio project ground to a halt last spring after the cabinet repair and refinishing was done.  Now I've finished one project, fixing up an old steel "ice cream chair" with a new wooden seat and some linseed oil on the steel frame.  That made room to start on the GE's electronic renovation.  Tonight was the first part--replacing all 5 grid cap wires, which were all rubber-insulated and crumbling.  Two were from IF transformer cans, so the cans had to come off.  On the first one, true to form, I got the sequence wrong--soldered the cap connector to the wire instead of soldering the wire to the IF, then poking the wire through the can, then soldering the cap connector on.

Next I'll make some sort of chassis holder so I can work on the underside, replacing capacitors and the rubber insulated wires that are placed so as to create hazards.

Chris Campbell

Bill

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Re: The old GE radio
« Reply #1 on: January 16, 2019, 06:22:33 AM »
Sounds like a fun project Chris.  And since this is the dark season what better time for in door projects.

Bill


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Re: The old GE radio
« Reply #2 on: January 17, 2019, 09:49:34 AM »
GE made some fine receivers and easier task to restore than most others.

I'd be tempted to replace the power supply caps first and try it out before replacing all the wax-paper caps. Your radio uses a 6L6 for the audio power amp, which seemed to be rare among radios that early.
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Dave

TC Chris

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Re: The old GE radio
« Reply #3 on: January 17, 2019, 10:58:47 PM »
I like the idea of just doing the filter caps first.  That one on the 6L6 plate was cooked-looking so I'll either do the series thing or buy another for it. But the others, well, some of them are nicely buried, so maybe I'll wait on those and leave them in if the radio works.  I'll focus on the crumbling rubber wire where it's close to the chassis or other metal.

I just walked out to the shop and retrieved my schematic.  What had looked like more electrolytics than I expected turned out to be dual-section electrolytics paralleled in a previous repair.  Then I looked closer at the big wirewound resistors, which turn out to be a replacement for most of the big chassis mount "Candohm" voltage divider.  So I'm guessing that at some past time, the filter caps shorted and took out the original resistor. 

The schematic also shows me that while GE went with a single-ended output amp, that big 6L6, they used two IF amps instead of the more common one.  And since this has tuned RF, the extra IF amp may make it a good performer.  The radio also has a tone capacitor that is switched in when the SW bands are selected.  So they designed for lower noise in SW and higher fidelity in MW.  Interesting. 

Chris Campbell


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Re: The old GE radio
« Reply #4 on: January 18, 2019, 01:04:47 PM »
Your wax caps are not necessarily a danger other than that output clipper. I bet that will come right up with just the power supply restored. The auto-tone on SW sounds like a clever feature GE would have promoted.

I have a small GE console from 1936, model A55 that has only 5 tubes 6A8-6K7-6Q7-6F6-5Z4. It is a decent-sounding set and receives as good as any other AA5. The "tone" control only switches in a .03 uf cap from the 6F6 plate to ground, there is also a .004 uf across the OPT primary.

I refinished the cabinet because the radio was a "wedding gift" from my wife 22 years ago, before she knew how much of a "curator" I was. 
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Dave

TC Chris

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Re: The old GE radio
« Reply #5 on: January 18, 2019, 07:21:02 PM »
Well, the output tube coupling cap can make me nervous.  Once I found a nice old Silvertone guitar amp in the trash.  It was a smaller one with P-P 6V6 output.  I took it home and plugged it in and it worked!  But then I noticed a dull cherry-reddish glow on the 6V6 plates.  Guessing that the bias was off, I replaced the coupling caps and all was well.  Now that's one I attend to for fear of burning up expensive stuff. 

My plan for this weekend is to pull the rectifier out and power up the power transformer to make sure it hasn't died.  That burned-up/replaced Candohm makes me a little nervous.

Chris Campbell

electra225

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Re: The old GE radio
« Reply #6 on: January 18, 2019, 08:18:38 PM »
Are you planning to install a fuse? 


It is amazing how much hack work an old radio can withstand and still work after a little TLC.  Radio repair shops sometimes did the minumum to get one going, out of the shop, and making the cash register jingle.  You'll put it back in better shape than when it left the factory.   :)
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TC Chris

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Re: The old GE radio
« Reply #7 on: January 19, 2019, 07:15:19 PM »
While Greg has his TV on the card table, I have my GE E-86 on top of the table saw.

This evening I walked down to Ace Hardware to buy an extension cord to make a cord for the GE.  It's cheaper than buying raw zipcord and a plug, plus I still have the short end I cut off to make a short extension cord out of.

After that was attached I pulled the rectifier out, poked the VOM leads in the socket's plate holes.  Whee, lots of volts (>500 VAC, 'cause that's where my VOM tops out unless I move it to the 5 KV input).  It bounced the needle a little bit.  That means I have a power transformer and can proceed.

So then I turned to the rubber-coated wires, the ones that lie against things and create a danger of shorts.  Geez, GE really packed the parts in tight.  I'm used to old Zeniths with lots of real estate.  GE probably worried more about RF performance and such.  The rubber-coated ones often bear against the chassis or other terminals. In any event, I worked until I had used up my red wire.  Now I need black, which will mean a trip to the hardware store tomorrow unless I find some suitable gauge in my wire stash.  Where the wires run to tube sockets or the IF cans, I've mostly been cutting off the old one, leaving a short length that I can curl up to make a solder terminal.  Un-soldering is not feasible because of the tight quarters.

Chris Campbell

electra225

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Re: The old GE radio
« Reply #8 on: January 19, 2019, 07:51:08 PM »
Sometimes you have gotta improvise!   ;) :) :-[


Grandpa always said that poor people had poor ways......
I don't need Google.  My wife says she knows everything.

TC Chris

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Re: The old GE radio
« Reply #9 on: January 20, 2019, 08:48:09 PM »
Another evening hunched over the table saw, soldering iron and pliers in hand, and the occasional @#$*!!! being uttered.  What helped was tonight's blues show on the radio.  In honor of the MLK Jr. Birthday holiday, he always does a gospel music show.  Wow, that warms up a cold night!  The only problem is that it's hard to dance around when you're trying to solder.  But now all the evil rubber-insulated wire is gone.  For some reason, GE only used it where it would lie against the chassis or bend around some other metal chassis item.  The fabric-insulated wire was all out in the open, where it would have been easy to get to. 

I think I've got a couple 16 mfd caps in my stash but I'll need to order up that .01, 1000 V cap in the output circuit.  Then I can fire it up and see if the remaining paper caps are functional enough to let it make sound for me.

Chris Campbell

electra225

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Re: The old GE radio
« Reply #10 on: January 20, 2019, 09:33:50 PM »
Congrats on progress! 


I worked on the TV chassis listening to a Bobby Vinton CD I made from records.  He was the male counterpart of Connie Francis.  The same sweet, rangy voice.  One of the songs on the CD was "Who's Sorry Now?" a Connie Francis standard.  You're right.  Tapping your toe while trying to solder takes more athleticism than I possess.   ;) :)


If it helps any......


I have that cap you need.  Laying on the card table........ :) ;) :-[
I don't need Google.  My wife says she knows everything.

TC Chris

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Re: The old GE radio
« Reply #11 on: January 20, 2019, 11:17:28 PM »
Well, I needed one more electrolytic cap, plus I figured it might be good to replace the line filter caps with modern safety caps, so I turned to Sal's for a quick order.  I'm buying multiples these days so as to have extras on hand for future projects. I don't usually waste too much time lamenting the loss of the "old days," but I sure do miss having an electronics-parts store or two in town.  The local ones gradually died off but we still had Radio Shack.  But now, it's all a matter of waiting for the delivery.

When I fired up the GE, minus rectifier, I was happily surprised to find that all the dial lamps worked.  That never happens.

Chris Campbell

ed from Baltimore

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Re: The old GE radio
« Reply #12 on: January 21, 2019, 07:53:49 AM »
           In my high school days, in the late 60s, there was a store in the northern Baltimore area called Baynesville Electronics and without them located 4 miles from where I lived, I don't think I ever could have sustained having electronics as a hobby. Back then they had bins and bins of surplus knobs and pots  that you rooted through to replace a worn out knob at least with the right shaft and sometimes the original style too. New tubes, fuses and Photofacts were behind the counter items, like cigarettes today. They had a nice selections of Thomas Sams "how to" books, like Using the Oscilloscope, TV Servicing, Tube Substitution Handbook. There was the U-Test-It tube tester always with a line of ambitious self-service hopefuls each with paper bags full of tubes from the family console color TV.  They had lots of small parts, like capacitors, usually in JameCo packaging, so you were never sure about diodes or FETs not being "seconds" that wouldn't even ohm out right.
         This store shut its doors just a few years ago. Even the Radio Shacks were the ones that didn't have the parts drawers, there the two types of Radio Shacks, and the rare ones had nice parts drawers.
          The march of time goes on and on !!

electra225

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Re: The old GE radio
« Reply #13 on: January 21, 2019, 10:38:04 AM »
I worked for Mr. Wells, the local Zenith dealer when I was in high school.  He was also the service facility for Magnavox.  There was a furniture store in a nearby town that handled that line.  Mr. Wells was NOT a  full-service shop.  Do not bring him a GE or an RCA anything.  The shop was in his walkout basement.  One whole wall was covered with shelves with any conveivable part you would ever need for a Zenith.  I remember he had a couple "porthole" masks hanging on the wall.  If I was working on something at home and needed a part, Mr. Wells was my go-to guy.  He would put the cost on my "tab."  He never sent me a bill.  I'd try to pay him, but he was always "too busy to mess with that now."  He only handled Zenith-branded tubes. 
I don't need Google.  My wife says she knows everything.

TC Chris

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Re: The old GE radio
« Reply #14 on: January 21, 2019, 02:18:55 PM »
I have a feeling that Zenith looked to impress by using great big chassis and lots of tubes.  That makes it easy to service because there's lots of room.  Just guessing now, but GE may have been more focused on good performance and less on PR, so the chassis is smaller and they didn't use a P-P output.  It's got a lot of RF coils, all well shielded, below deck.  But wow, it can be close quarters when replacing components.

Today I replaced the filter caps and another electrolytic and freed up the volume control.  It was extremely stiff, probably from somebody using oil on the shaft.  I've been using Liquid Wrench to dissolve the crud.  The band switch also scrolls through three bands on separate dial scales, and the rolling dials needed to be freed up with the solvent too.  Then I spent some time dealing with cold solders on the wirewound resistors that replaced the burned-out Candohm.  I'm just hoping that those were done with electronic accuracy.  It's hard to trace things because schematics show as-designed and the device is as-built (or fixed).  Often, components are attached to points that are electronically accurate, but not the physical location suggested by the schematic.  Where's that magnifying glass so I can read this Rider schematic.... Now I'm just going to wait for Sal to send me some more caps.  Maybe I'll run the tubes through the tester to make sure there are no dead filaments or simple shorts.

Chris Campbell