Author Topic: Help identifying my console & an issue!  (Read 620 times)

Dexter

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Help identifying my console & an issue!
« on: March 10, 2018, 08:15:26 PM »
Hello!  First timer here...  picked up a Magnavox from a friend who was moving.  Sounded great for a couple of months while it's been in my possession (my friend hardly ever used it).  But now, having issues with sound out of one set of speakers.  I am certainly not an audiophile nor an expert when it comes to antique electronics but am decently handy and willing to take the time to learn and get this unit sounding great again.  I've really enjoyed pulling out some records (and picking up a few new-to-me!) and dropping them in!  Looking for help!

First, I see the model number is '1P3661'.  I haven't been able to find out the actual name though... thoughts??

Then, second, everything seems to function great - radio and record player.  Like I mentioned, the left speakers do not handle the high pitched sounds anymore (they did the past few months) and come through 'scratchy', for lack of better term.  Thoughts??

I don't know where to start here, but I've been combing this site and feel like I'm in the right place!  Thanks in advance!

 -Adam

electra225

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Re: Help identifying my console & an issue!
« Reply #1 on: March 10, 2018, 10:19:38 PM »
It is an Astro-Sonic model from the late 1960s or so.  Solid state.  My suggestion is that you clean all the controls, particularly the external speaker switch and the function switch.  These controls can become electrically "dirty" and can cause all kinds of problems.  It might be a good suggestion to replace all the electrolytic capacitors in the amp and tuner chassis and replace the speaker crossover capacitors.  Good luck.
I'm great at multi-tasking.  I can listen, ignore, and forget all at the same time.

ed from Baltimore

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Re: Help identifying my console & an issue!
« Reply #2 on: March 10, 2018, 10:57:50 PM »
        This is a treat !   Just saw this  new post with no replies yet so here goes:
   
         I didn't look up the model number and am hoping its a stereo console with left and right side woofers and left and right front cone or horn tweeters. Treble and bass controls either stepped or continuously variable.   
         If that's the case listen to the FM radio with the tuning dial at a dead spot on the dial, no stations, just a rushing hissing noise. Turn the volume up to hear it well and if there's a squelch control rotate it so that the hiss comes through.
        The side speakers, meaning the low frequency woofers,  should sound alike---no scratchiness as you turn the volume up and down. Place your ear so that you are mainly hearing first one side woofer then the other, and ignore what comes out of the front grill cloth. If the scratchiness is on the left side speaker, rotate the treble control back and forth continuously and see if the scratchiness goes away.  If it improves after  several back and forths you probably had oxidation and dust on the treble control.
         If the two sides  sounded alike, now place your ear close to the front---not side----speaker cloth on the left and then on the right.  If the scratchiness comes from the left front, you may have loose wiring between the left woofer and the left tweeter. Or bad crossover components which are usually tracible between the left tweeter termnals back to the amplifier or the speaker selector switch, if it has one. The voice coil in the tweeter itself may be intermittant.
         There might be other possibilities, like a bad stereo phono  cartridge, but if FM, AM, and phonograph all have the problem, there's not much else it could be----assuming the sound from the side woofers is the same and the bad sound is coming out of the front tweeters.
          If the left woofer and left tweeter both have scratchiness, and the treble control rotation doesn't clear it up, some bad component or loose solder connection in the amplifier or tuner chassis might be reaponsible for intermittant or scratchy treble loss.  But an intermittant tweeter voice coil is most likely.

TC Chris

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Re: Help identifying my console & an issue!
« Reply #3 on: March 10, 2018, 11:31:25 PM »
Remember the old rule about always checking the least complex explanation first.  The simplest explanation (and cheapest fix) for a one-channel loss of high frequencies is the crossover capacitor.  These all have simple high-pass capacitors to feed the tweeters.  Of course, it could be the speaker itself, especially if it has been driven hard by an amp that's distorting, but first check for the crossover caps.

Chris Campbell

Dexter

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Re: Help identifying my console & an issue!
« Reply #4 on: March 30, 2018, 10:23:38 PM »
Thanks everyone that's responded.  Much appreciated.
I haven't had the time to actually work on this yet, but I have been reading a ton to understand what I need to do.  Looks like plenty of cleaning of controls and switches is needed (makes perfect sense) and replacement of the capacitors is needed as well (understood - makes perfect sense after learning about 1960s capacitors and what time can do to those guys!).
So, I believe my next step is to identify the capacitors I'll need to install and get those (as well as update my soldering station and supplies).  I see there are capacitors on the main chassis/board as well as by the speakers (guessing the latter are the crossover capacitors mentioned?). Either way, I'm having a tough time reading the info on these capacitors and figure a schematic would provide the info I need to purchase new ones without fail.  Any ideas where to find the one for my set?  I've tried SAMS Technical Publishing website and a few others but I cannot find 1P3661 anywhere.  Thoughts??
Again, much appreciated for the help here folks - from what you've told me and my investigation all over the internet, replacing these capacitors sounds like the absolute root cause and I'm definitely looking forward to getting in there soon.

19and41

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Re: Help identifying my console & an issue!
« Reply #5 on: April 02, 2018, 06:39:58 PM »
Ith number you are using is the end item model number. On most Magnavoxes I have had experience with the model numbers that you would look up a Sams folder with are marked on the component itself  have a good look at the receiver itself in the cabinet.  It should have 1 or more numbers on it.  write them all down and look them up.  The values for the crossover caps on my unit were on the build diagram in the cabinet.
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Dexter

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Re: Help identifying my console & an issue!
« Reply #6 on: April 07, 2018, 06:21:48 PM »
Thank you!  I found the Chassis number and the related Schematic on SAMS.  Again, really appreciate all the help here!

Next question, if I look at the list of Electrolytic Capacitors, I'm not sure what units I'm dealing with.  Can someone confirm for me that, for example, C1 is rated at 1000 micro-farads and 30 Volts?  And that would be the same all the way down (300 uF, 400 uF, 200 uF, and so on...)??

And then the only ones that would look odd to me still are C18 and C23 - what does 25 "VNP" mean?

Thanks all!!

danrclem

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Re: Help identifying my console & an issue!
« Reply #7 on: April 07, 2018, 07:22:50 PM »
That would mean that they're 25 volts non-polar electrolytic.  They should be for the speaker crossover.  Most electrolytics are polar with a positive and a negative. 

19and41

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Re: Help identifying my console & an issue!
« Reply #8 on: April 07, 2018, 09:16:20 PM »
And the other caps are usually expressed in microfarads unless otherwise identified.
"Any sufficiently advanced technology is indistinguishable from magic."
Arthur C. Clarke

Dexter

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Re: Help identifying my console & an issue!
« Reply #9 on: April 08, 2018, 07:52:36 PM »
Excellent - thank you both for the info.  Making progress here!!