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Silvertone 7057 Audio "Cross-Talk" Problem?
#1

Hello,
I've finished restoring the chassis to a Silvertone 7057 Radio/Record Player/Record Cutter. It seems to work fine with the exception of one very annoying problem. When in "record player mode" (arm lifted) I can still hear radio audio for strong stations. Icon_sad  Icon_sad  Icon_sad

What I know is that:
  • The radio audio goes to the turntable and is looped back in (green jumper) when the arm is down. When the arm is up the phono cartridge (bad of course) is suppose to supply the signal.
  • If remove the jumper and am tuned to a strong station I can hear the audio at a clear, but low level with the radio volume (left of tuning - see photo) at min. Increasing the radio volume increase the radio audio a bit, but not much.
  • If I turn the radio volume full off a switch engages that effectively disconnects the detector. That eliminates any radio audio as one would expect. Since the radio volume controls the phono volume turning the radio off isn't the solution.
  • If I ground the detector output (C11) the audio goes away.
  • If I turn on the mike audio (mike volume just past min, a switch connects to R27) it can amplify the "cross-talk" as the mike volume is increased just about as well as the radio volume control. This leads me to believe it's more affected.
  • If I yank the 6SQ7 and  stick semiconductor diodes in the socket in place of the tube I still have cross talk. So it's not the diodes and triode in the tube not playing well together. The mike amp obviously doesn't work when I do that.
  • The mike actually works and sounds good.
  • I connected the mike to the phono input and I can hear low audio. The mike level doesn't seem to be the same a the cartridge must put out.
  • I reflowed the solder on several grounds - nothing. Grounded the center lug of the terminal strip below the radio volume control - nothing. The IF transformer is grounded there with several caps.

    I'm almost ready to conclude that it's just a design issue of some sort but don't want to throw in the towel just yet.

    The other thing that would be helpful is if someone knows where a manual is available for one of these.

    Any suggestions would be appreciated.

    http://www.nostalgiaair.org/pagesbymodel...017637.pdf

    Thanks,
    Greg


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Can't think of anything witty.
Greg O.
Whitehall, PA


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Silvertone 7057 Audio "Cross-Talk" Problem? - by Greg - 03-12-2018, 07:22 PM



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