Author Topic: Magnavox Micromatic Model: 2ST647 New Needle - No Sound  (Read 4365 times)

John B

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Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« on: March 21, 2018, 05:00:19 PM »
My Magnavox Micromatic Model:  2ST647.  I put in a new needle and the changer works nicely after I cleaned and oiled it but I am not getting any sound.  The wires from the console go underneath the house to a Pioneer receiver.  Ground wire also connected.  Speakers in the console work.  I switched to another input but no luck.  Could it be the cartridge?  I can't see any damage and connections look clean enough  and I'll continue to search for answers.

Thanks for any help,

John B

TC Chris

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Re: Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« Reply #1 on: March 21, 2018, 07:48:38 PM »
Can't quite figure out the part about wires under the house to a Pioneer receiver.  Plug your changer into the right inputs on the console and see what happens.  If no sound, probably no luck with the cartridge.  Replacing a needle has no effect except on record wear, really--you should get some sound with even a worn one if the cartridge is alive, the wring is intact, and the electronics are working properly.  Try plugging something else into the phono input and see what you hear.  If the output from  the device you plug in is too high, it may sound distorted, but at least you'll know the amp s working.

Chris Campbell

John B

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Re: Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« Reply #2 on: March 21, 2018, 08:27:37 PM »
TC Chris,

The wires are connected from the RCA's that come from the needle and cartridge  circuit board under the turntable and go to the receiver in the other room.  It has worked that way, I think.  I switched the CD inputs to the Phono inputs and I get sound.  I found a diagram in the console that shows where the RCA's from the cartridge go, they're three pairs and I tried them but I think they are all inputs.  Anything that plays through the stereo receiver can be played through the console speakers because the receiver has A & B speakers.  I got a number from the cartridge and I'll look it up just in case (36758-2).  Do you think that I should try to put the RCA's into the inputs in the console and then go from the speaker output to the stereo receiver?  I'll keep trying.

Thanks for your reply,

John B 

electra225

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Re: Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« Reply #3 on: March 21, 2018, 09:18:11 PM »
Two wires from the changer cartridge goes to RCA inputs on the rear apron of the tuner chassis.  Marked Phono.  Can't miss them.  Then switch the function switch to "Stereo" and see if the changer talks.    There will also be tape inputs and outputs.  Also inputs for the MPX adapter.  All clearly marked.  There should be a paper diagram in the floor of the cabinet that shows how things hook up as well.  Information is available on this forum at the top of the page, under "Downloads".  Easy to follow and well organized.  Good luck.


Here is a picture of my Imperial chassis.  Yours may not be identical to this one, but this shows how the phono is connected to the tuner.
I don't need Google.  My wife says she knows everything.

John B

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Re: Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« Reply #4 on: March 21, 2018, 09:50:18 PM »
electra225

I see the diagram and I tried all three pairs and no sound, only faintly from the needle.  I don't know if I'm using the right side of the needle because one side is marked "S" and the other side there is no marking.  Anyway, years ago I made the console into a speaker from the Pioneer receiver in the other room and that works.   I have the phono RCA's going to Pioneer receiver, bypassing the inputs inside the console.  That way I could have the records heard in all the house.  I guess I have things mixed up and I have to figure it out all over again. 

John B 

John B

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Re: Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« Reply #5 on: March 22, 2018, 10:40:04 AM »
I'll try to get the speakers working normally again so that I can use the stereo and phono AT the console as well as through the Pioneer.  Right now I don't hear anything from the stereo in the console.  The console has a switch at the back that allows Internal, External and Both speaker modes.  I can use Y-connectors with the phono RCA jacks with one pair to the chassis and the other to the Pioneer.  I hope I can do it.  Years ago I changed things but I knew as much about stereos then as I do now.  Zip!  I might end up with bookcase speakers in my living room but that's what I've tried to avoid.

John B.

John B

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Re: Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« Reply #6 on: March 22, 2018, 02:42:03 PM »
I took some more pictures underneath.

John B

John B

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Re: Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« Reply #7 on: March 22, 2018, 04:11:28 PM »
In INT I can faintly hear the radio of the Magnavox, as well as in BOTH.  In BOTH is when I hear the Pioneer but not in EXT.  Nothing in EXT.  So it's now a problem of how I can get sound from the console itself and to isolate the Pioneer to EXT.  Play around with the wires?  Working at it!

John B

John B

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Re: Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« Reply #8 on: March 22, 2018, 05:33:16 PM »
Just one more observation:  There is a sticky, oily substance on the wires but I cant see a source.  It's not covering everything.  Could it be a blown capacitor?  I've swapped capacitors in a computer monitor last year so that's something I can fix.  It's a lot of work to get the chassis out to work on though.

John B

electra225

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Re: Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« Reply #9 on: March 22, 2018, 09:32:36 PM »
The needle is a flip style.  One side is for LP's the other for 78's.  The "S" position should indicate "stereo" or the needle you would use for LP's.  I would not couple the output of the Pioneer to the input or parallel it with the output of the Magnavox amp.  You are liable to mess both of them up.  The sticky, oily substance on the wiring is what I affectionately refer to as "Magnavox goo."  I know not of its purpose, nor from whence it comes.  It is totally normal, harmless and can easily and safely be removed with a rag dampened with lacquer thinner.  You are messing with the external speaker switch.  One position is likely "Int", one is likely "both" and one is likely "ext."  The internal position will allow audio to go thru the internal console speakers.  The "both" position will allow audio to go thru both the internal console speakers and the external speakers.  The "ext" position will allow audio to go out only the external speakers.  Wiring your setup so the Pioneer comes thru one position and the console another is not only more trouble than it will be worth, but also likely rife with the possibility of losing your Pioneer receiver's amp.  I'm guessing you may have already lost the one in the console.  If you hear the cartridge output in the Pioneer setup but not in the console amp setup, it is a good bet the problem is not in the cartridge.  Where else it could be without my actually having eyes on the project, I would not hazard a guess.  I do wish you the best of luck with your project.
I don't need Google.  My wife says she knows everything.

John B

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Re: Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« Reply #10 on: March 22, 2018, 11:38:35 PM »
electra225,

I understand now.  The EXT meant from the console TO external speakers.  Not From the Pioneer into console.  I don't think there is damage to the Pioneer amps but I think the Magnavox amp might be damaged.  I am enclosing a picture to ask if that is an amp or transformer?  I connected the RCA's from the cartridge to the Pioneer and I got nothing which, I guess, means the cartridge is bad.  I can use small bookshelf speakers in the living room so that I can hear the CD player and other stuff.  Not a problem.  I want to keep the Magnavox because it's a nice piece of furniture and has good speakers.  I'll get it right. 

Thanks for your help,

John B

Bill

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Re: Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« Reply #11 on: March 23, 2018, 10:28:33 AM »
That is a transformer and it looks like it might be the transformer for the tuner.

Bill

John B

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Re: Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« Reply #12 on: March 23, 2018, 11:18:28 AM »
That is a transformer and it looks like it might be the transformer for the tuner.

Bill

The wires coming from it look a little crispy.  I think that if I take the chassis out I'll look for bulging capacitors.  Some videos on YouTube show a guy replacing everything but I'll keep it simple.  I haven't heard anything about fuses so I guess they aren't there.  I think it will be a limited operation because I am able to hear something, albeit faint.

John B

TC Chris

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Re: Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« Reply #13 on: March 23, 2018, 07:20:09 PM »
Transformers often operate at higher heat that other components, and sometimes the leads do get a bit "crispy."   Don't molest them and provoke any damage. 

If you're finding this interesting and want to learn more, here are some suggestions to start.  (1) YouTube videos.  They exist on every subject.  (2) Sign up over on Antique Radio Forum and see if you can find somebody experienced near where you live.  Most people with hobbies like to share knowledge and interest.  I'll bet you might find somebody who would come over and examine the devices with you.  And then there's the old faithful... (3) reading.  People often recommend the Radio Amateur's Handbooks, older varieties, for their coverage of electronic fundamentals. 

Chris Campbell

John B

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Re: Magnavox Micromatic Model: 2ST647 New Needle - No Sound
« Reply #14 on: March 23, 2018, 07:40:56 PM »
Chris,

I won't borrow trouble and mess with the transformer, I'm after capacitors and maybe transistors.  Whatever looks bad.  I don't have skills with multimeters but I swapped capacitors in a monitor last year.  I'm watching lots of YouTube (check out my video:  O'Keefe & Merritt Clock Replacement Fit Up).  I'm trying to find a topic very similar to mine.  I'll try Antique Radio Forum.  I can look up on Craigslist for help and then there is the TRW Swapmeet on the 31st.  I won't be doing anything until I more or less sure of what I'm doing.

John B
I'm in Long Beach CA in case anyone wants to fly over.  Lots of sunshine.