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 Post subject: Sad Demise for a GE SuperRadio
PostPosted: Tue Sep 05, 2017 9:59 pm 

Joined: Mon May 04, 2009 3:53 pm
Posts: 99
The attached image is from eBay. The model I own is almost identical.

I purchased a new GE SuperRadio many years ago for my workshop. I built a special protected shelf, far
away from power tools, sawdust, etc. Connected to an external antenna, it worked perfectly for more than
30 years!

A few hours ago I had a freak accident in my shop. A piece of scrap wood was ejected from a table saw.
It kind of flew across the shop like a missile and hit my SuperRadio. Nothing was damaged on the outside
of the case, but there is a serious problem. I can hear all the AM/FM stations at a very low volume. The
audio potentiometer has no effect on the sound.

I immediately opened the case, hoping the repair would be simple like a damaged wire. No such luck. All
the wires are securely soldered.

The circuit board is 99% discrete components. There is one 16-pin and 8-pin DIP. Something inside the
radio was damaged from the impact, but I don't see anything obvious. No cracks in the board. Hard to
believe, but everything looks very good!

I'd like to keep it, but I cannot devote endless hours tracking down faulty components. I'm guessing some
of you guys own (or owned) a GE SuperRadio. I've got barely audible volume and the pot does nothing when
rotated. If you know, which components should I test?


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 Post subject: Re: Sad Demise for a GE SuperRadio
PostPosted: Wed Sep 06, 2017 10:04 am 
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Joined: Sat Aug 12, 2006 4:17 pm
Posts: 1247
fine-tune,

Could you give us the full model number?

Also.......

Break out the magnifying glass, and start looking very carefully at the solder joints.
Start from where the speaker connects and work back to the Amplifier section.

Quote:
I've got barely audible volume and the pot does nothing when rotated

It doesn't effect it at all?
Check and see if the Volume Control Knob has a mark or dent in it.
If it does, then that is where the wood hit the radio, damaging the volume control.
{You'll need to look at the backside of the volume control, to see if it is pushed out.}
Image Image
If it is soldered down to the PCB, check the solder joints to it.

This has three Potentiometers controls on the front of the radio as well.
Better check them as well.


Signed: Janitor Tzap


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 Post subject: Re: Sad Demise for a GE SuperRadio
PostPosted: Wed Sep 06, 2017 12:08 pm 
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Joined: Thu Oct 26, 2006 7:11 pm
Posts: 1255
Location: Maryland
Odds are in your favor that it is a break in the circuit board. Analytical troubleshooting is a crap shot.
Look first around the heaviest components, solder them all then branch out from there. A break may not be obvious so, do them all!
Let us know!



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“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
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 Post subject: Re: Sad Demise for a GE SuperRadio
PostPosted: Wed Sep 06, 2017 7:17 pm 

Joined: Mon May 04, 2009 3:53 pm
Posts: 99
I don't think it's an exaggeration to say, the GE SuperRadio was the best portable AM/FM radio ever made.
With a decent external antenna, you could pick up AM stations thousands of miles from your location.

Replacing a transistor, resistor, or capacitor is no problem. However, you're not going to find exact
replacements for the pots and many other components. I must have hundreds of linear and audio pots.
None can be easily shoehorned into this SuperRadio.

If I was an old radio collector, I would probably own several non-working GE SuperRadios. Combining the
components from a few non-working units would make a fully functional radio.

I'm sure you're right, Janitor Tzap. The impact from that "unguided missile" could have damaged almost
anything. My SuperRadio has a 4.5 inch speaker and a tweeter. I'll rework the soldered joints.

I examined the circuit board using a headband magnifier. There could be several minute cracks that are
impossible to see.

The volume control pot may have been clobbered by that scrap of wood. I could unsolder the pot and try
a substitute. If it worked I'd have to find an exact replacement, or at least something that would fit on
the board.


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 Post subject: Re: Sad Demise for a GE SuperRadio
PostPosted: Fri Sep 08, 2017 5:39 am 
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Joined: Sat Jul 22, 2017 2:26 pm
Posts: 33
Shoehorned? So, I guess this radio is really tightly packed. I remember my old Sylvania was like that, and it was hard to work on. If it weren't for the dense packing, you might work backwards from the speaker, putting a tickle on the input to the audio section and so on. I don't imagine a schematic is available.


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 Post subject: Re: Sad Demise for a GE SuperRadio
PostPosted: Sat Sep 09, 2017 12:16 pm 
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Joined: Thu Oct 26, 2006 7:11 pm
Posts: 1255
Location: Maryland
You should be able to bypass a bad pot for a full volume test. Connect the center pin to the input pin, usually the right pin facing the back.
If indeed the pot is bad, post a picture of it with a scale laying next to it, or on a piece of graph paper for measurement reference.
It is surprising what some of us may have at the bottom of our junk boxes.....
TV Channel selector knobs anyone?



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 Post subject: Re: Sad Demise for a GE SuperRadio
PostPosted: Tue Sep 12, 2017 9:43 pm 

Joined: Mon May 04, 2009 3:53 pm
Posts: 99
I tried a substitute speaker and volume control. No change. The power suppy is ok. It's a basic four diode
bridge.

This SuperRadio has 22 electrolytics and 11 adjustable coils. All of the components are old. The impact from
that scrap of wood may have been "the straw that broke the camel's back," if you know what I mean.

I've checked numerous voltages and examined most of the components with a headband magnifier. Two hours
of tinkering with this non-working SuperRadio is my limit. When I was a boy I learned electronics by repairing
damaged radios and televisions. An enthusiastic teenager interested in an electronics career might have fun
repairing this SuperRadio.


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 Post subject: Re: Sad Demise for a GE SuperRadio
PostPosted: Wed Sep 13, 2017 2:23 am 
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Joined: Thu Oct 26, 2006 7:11 pm
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Location: Maryland
Almost certainly, physical impact causes physical damage.

Radios are designed in stages with specific functions. Have you tried signal injection or tracing to find what stage has the fault? Making voltage measurements, and not knowing what to expect from data or prior knowledge, is futile.



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 Post subject: Re: Sad Demise for a GE SuperRadio
PostPosted: Wed Sep 13, 2017 3:17 pm 
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Joined: Sat Aug 12, 2006 4:17 pm
Posts: 1247
I agree with Lenp.

It's too early to just give up on it now.

See if you can locate the Amplifier Section, and try injecting a signal at the input.
If you got a strong output signal coming out of the speakers.
Try then injecting a signal at the Volume Control.
If you got a strong signal, the problem is before the Volume Control.
If the signal is bad, then the problem is somewhere between the Volume Control,
and the input to the Amplifier.

If the signal was still weak coming out, after injecting a signal in to the Amplifier Section.
Then you need to go through that section.

I've found schematics for the GE SuperRadio.
But I don't know if they are for your model.

Can you please give us the model number?


Signed: Janitor Tzap


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 Post subject: Re: Sad Demise for a GE SuperRadio
PostPosted: Fri Sep 22, 2017 4:31 am 
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Joined: Sat Nov 08, 2003 1:01 am
Posts: 1560
Location: Phoenixville, PA USA
Also, since it was a sudden physical impact, have you tried pressing/moving components while the unit is on and can hear the weak output? Rubber / latex / nitrile gloves will keep you safe from any voltages ptesent while powered.

As has been said already, suspect the heavier / larger components as they are most subject to inertia and torsion. It may be possible that a large electrolytic started to separate at the base and you just can't see it. The physical movement test should give some sort of change in audio, even if for a millisecond.

CeaSaR



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