Author Topic: FM-33 radio  (Read 598 times)

TC Chris

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FM-33 radio
« on: March 06, 2019, 11:06:28 PM »
I've had the FM-33 radio sitting on end in a corner of the kitchen for quite a while.  It needs new filter caps, as when I plugged it in a couple years back it sounded hummy-grainy,  I was sort of hoping that my capacitor stash would hold whatever it needed.  So I took it out to the shop, on the table saw workbench, and took it apart.  As usual, there were a coupe hidden screws to slow em down.  When it was apart, I identified the caps' values and checked the stash.  Nope, not a one.  Mouser, here we come.  Lately I have been buying extras whenever I order parts like that so in the future when I need one, it will be there.  I have finally figured out the Mouser online ordering system so it's not too had.  The radio uses an 1893 lamp, and that's likely dead too, so  ordered a bunch of those.

The radio has a 6x9" speaker and a little cone tweeter.  The amplifier output transistors are push-pull and fairly sizeable.  It's a stereo radio but the second speaker unit wasn't with it when I got it. I'll make do with a misc. one until I get it working, and then maybe make up one to match the radio's shape and style. The chassis and cabinet both appear to be of Asian build.  The amplifier chassis caps are Nichicons.  I'm hoping that the Nichicons are still functional.  The power supply caps are less elegant. 

Now I've got to wait for the caps to arrive.  That may give me time to find a place for the GE radio in the house.   I got my little Zenith 6G05 table radio going after its rectifier lost 1/2 of its center-tapped heater.  The tube tester apparently only lights up the higher-voltage half, so it didn't show up as dead when I tested.  In the radio, however, it interrupted the series-string heater line and nobody lighted up.  A  new 35W4 solved the problem.

Chris Campbell

Bill

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Re: FM-33 radio
« Reply #1 on: March 07, 2019, 01:23:13 PM »
I need to ask Chris, what's a FM 33 radio?

Bill

TC Chris

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Re: FM-33 radio
« Reply #2 on: March 08, 2019, 12:42:59 AM »
Magnavox tabletop stereo radio (originally had separate 2nd speaker,; mine came without).  Solid-state.

Chris Campbell

Bill

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Re: FM-33 radio
« Reply #3 on: March 08, 2019, 11:51:59 PM »
Thank you, and very nice.

Bill

TC Chris

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Re: FM-33 radio
« Reply #4 on: March 09, 2019, 10:36:20 AM »
Mouser informed me that they had shipped my order of filter caps & dial lamps for the radio, so maybe it will be up and running soon.  It has a phono input (likely high-level, as for a ceramic cartridge, and without equalization) so I should be able to run other devices through it.  I have a few options for the 2nd channel speaker and will see which works best.  I may have to make up an enclosure and pop a 6x9 into it.

Chris Campbell

TC Chris

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Re: FM-33 radio
« Reply #5 on: March 27, 2019, 11:47:14 PM »
I went out to the shop and replaced filter caps tonight.  The originals were two dual-section cardboard cans.  One was common-negative, the other common-positive.  What?  Are you sure??  But luckily, Magnavox had labeled everything under the circuit board, showing the commons, one neg, one pos.  I replaced with individuals.  I had t re-solder the antenna twinlead to the terminals on the back of the radio. Then I wiped it down with vinegar (mold from its time in my basement) and put it back together.  No sooner did I get the screws all back in place than I remembered that I had not replaced the dial bulb.  @#$*^!!!

Tomorrow night, that one.  Then I'll see how it sounds.  Or maybe if....

Chris Campbell

TC Chris

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Re: FM-33 radio
« Reply #6 on: March 29, 2019, 12:06:06 AM »
Bought my new screws... but first plugged it in and turned it on.  NOTHING.  No noise, no crackle.  Eventually I remembered that I hadn't hooked the speakers up.  Oops.  Pull chassis out, replace dial lamp, hook up speakers, plug in, turn on, and yes, sound.  I have a speaker found at curbside, "Juliette" (i.e., cheapo), but it's almost the same size as the radio, and the speaker's efficiency seems to match the internal ones, so now I have stereo.

It's a bit bass-heavy and on some stations a bit grainy.  I did not replace the output capacitors because they were nice-looking Nichicons, but maybe I should.  And it probably has a raft of other electrolytics too.  It did sound a bit better after it had played a while.  I'll wait and see.  It has phono inputs (surely for a ceramic cartridge) that I can probably run a CD player or my iPod into.  The dial markings seem to be quite a bit off.  Maybe the big tuning cap pulley slipped--I'll see if AM and FM are equally off.  Then I'll do a bit more clean-up and then screw it back into the cabinet.

Chris Campbell

electra225

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Re: FM-33 radio
« Reply #7 on: March 29, 2019, 10:27:22 PM »
Nice radio, Chris.   :) :)


I have never seen a Magnavox dial in my life that the pointer was accurate.
I don't need Google.  My wife says she knows everything.

TC Chris

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Re: FM-33 radio
« Reply #8 on: March 30, 2019, 05:57:08 PM »
This is way off--91.5 shows up at about 96 something.  If it's mechanical, I can fix it.  If somebody has fiddled with the oscillator, I'll leave it. Unless I can't resist.

Chris Campbell

TC Chris

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Re: FM-33 radio
« Reply #9 on: April 01, 2019, 11:05:26 PM »
Tonight I took the chassis out and cleaned up the inside of the cabinet more carefully with vinegar to kill off some mildew. I washed the dial and knob area and the knobs themselves. Then I put it all back together and hit the walnut wit Howard's.  Wow, it really made the wood glow.  This is an oiled finish, no film of lacquer, and the Howard's added the color that had faded.  It will sit out in the shop over night to set up and then I'l bring it in with its damned-close-matching second speaker and try a video.  This radio has a phono input so I should be able to run a CD player through it.  The dial pointer lines up properly at the ends of the dial's gradations, and the tuning cap is completely closed at one extreme, so if the frequencies are off, it's the oscillator and not a mechanical problem.

Chris Campbell

TC Chris

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Re: FM-33 radio
« Reply #10 on: April 02, 2019, 08:14:01 PM »
After letting the Howard's dry overnight, I made a short video tonight of the radio and its new companion speaker playing.  Now, a video of a radio playing is right up there with watching paint drying, I know, but true Magnavox fans might want to see one of the brand's smaller offerings in action.  The radio is a bit bass-heavy, even with the tone control turned all the way to treble (it's a treble-cut control, so it doesn't reduce bass).

But now it looks good and performs adequately.  My house is near "radio hill" where  there are a bunch of transmitting antennas, so I tend to get overloaded front ends on lower-end FM radios.

Here's my YouTube link:
https://youtu.be/a_TGhwf6H4I

Chris Campbell