GE 212 restoration
 

I picked up this GE 212 AM/FM radio after receiving a tip that it has the same look as a GE 810 TV. The only obvious defect is the dial pointer. I could see the thin red pointer floating behind the glass but the hub it mounts to had disintegrated. Apparently, it's a common issue with these radios.

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I removed the back and was treated to an AM loop antenna that had separated from the backer. It's made from thin rectangular stock bent into concentric rectangles.
It should be fun to glue back down while avoiding a single short!
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The speaker and dial are in good shape. Just some residue from the old dial pointer to clean off.
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I figure I can flatten out and reuse the red piece. Perhaps I can use an old cream colored knob for the rest.
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The underside is nicely charred around the 35W4 rectifier. Nothing too serious I hope.
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probably from alot, and i mean ALOT of use.

If it turns out half as nice as your 810 it will look amazing! Can't wait to see this one get done.

Here's a closer look at that blackened corner.
http://www.bobandersen.com/images/GE%20212/02-20.jpg

My first thought was the filter cap had gone bad and the 18 ohm flexible resistor going to it had fried. Nope. I removed it and it's fine.
http://www.bobandersen.com/images/GE%20212/02-23.jpg

35W4 tests fine as do the other components in the immediate area until I rotate this cap around. One end breaks off and I see a charred interior.
It must have really smoked when it failed!
http://www.bobandersen.com/images/GE%20212/03-02.jpg

I'll try cleaning up that area using some QTips and alcohol.

I had been considering restuffing the paper caps until I tried melting out one of the SEALDTITEs. They're not the usual paper tube sealed with wax.
More like a hard resin tube with a paper label. Smells horrible when melted :yuck:

So, I'm just soldering in new caps. Should be ready for a powerup tonight.

With all that soot you might want to check resistance between tube socket terminals after cleaning. Some of the nasty might have got in between the wafers.

I finished recapping - it's surprising how many caps they crammed in there! I didn't have any 75 mfd caps on hand so just tacked in some 68 mfd. The correct caps should arrive shortly.
http://www.bobandersen.com/images/GE%20212/04-01.jpg

http://www.bobandersen.com/images/GE%20212/04-02.jpg

I used some mineral spirits and q-tips to clean up the corner and made sure it was completely dry before powering it up.
The cap that burned up was going from the AC line to ground. I replaced it with a proper safety cap.
http://www.bobandersen.com/images/GE%20212/04-04.jpg

I slowly powered it up and just got static on AM, but FM showed signs of life. I cleaned the volume control with deOxit and hooked up a proper dipole FM antenna. Finally, music came booming through :music:
http://www.bobandersen.com/images/GE%20212/04-03.jpg

AM is still not working but that's probably because I don't have the internal loop antenna plus trimmer cap connected.

I always learn from your posts,, very nice work.

off topic: Hey, Where did you get that humongous spool of solder in your second pic?

Surplus Sales of Nebraska. It's a 1 lb spool of Multicore SN63. It's OK, but I actually prefer Kester "44" becuase it's rosin works better. I have 2 lbs of that on the way. It should last me a long, long time.

thats what I had was kester. i went through a 1lb spool in about a year.

I've hooked up an antenna and AM is still really bad. I can tune in a few stations, but they are very garbled and noisy.

Since the AM/FM circuits share so many parts there isn't much to check.

First, I checked the tubes. The 19T8 combo FM descriminator, AM detector and audio amp was weak so I replaced it.

No change.

Moving on the the other tubes I was surprised to discover a 12BA6 in the place of a 6BH6! That's the limiter and since FM is working fine it must be a valid substitute.
I popped in a 6BH6 and there was no noticeable difference. I suppose a 12 volt filament tube might be good to keep in there to compensate for higher AC outlet voltages :scratch2:
http://www.bobandersen.com/images/GE%20212/12BA6.jpg

Next, I checked the two AM IF cans and their associated resistors and caps. They all check out including the IF windings. All measure around 15 ohms as indicated on the schematic.

Then, I tried a little aligning by ear but got no improvement. That leads me to suspect bad mica caps inside the IF cans. I popped the shield off one and discovered they are riveted to the bottom.

Retrochad repaired IF transforms just like this in a recent YouTube so I have a good idea what's involved. Only one problem - the values are not marked on the schematic or caps :(

I do have a part # at least M76J433-1 188. Does anyone know what those caps values might be ? Is suppose I could determine them experimentally if it came to that.
http://www.bobandersen.com/images/GE%20212/AM%20IF2.jpg

I just ran into the same problem with an AA5-I imagine there is a ballpark value for these micas, you'll just have to align the if slugs again.

I did some experimenting with loop antennas and the AM reception improved quite a bit. I still have some work to do on the damaged one that came with this radio though. Hopefully, once that's done my AM reception woes will be over.

I really don't want to have to rebuild those IF caps :no:

Another 212 popped up on eBay with an intact dial pointer: http://cgi.ebay.com/VINTAGE-BAKELITE...-/160512582654

There are some good reference photos that I've saved to my computer.

I didn't look at the schematic, but if it's like most AA5 etc. radios, the loop antenna is a necessary part of the tuned antenna circuit and the radio won't work without it on AM. Time to glue that mess back together!