Silvertone 7057 Audio "Cross-Talk" Problem?

Silvertone 7057 Audio "Cross-Talk" Problem? - Printable Version

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Silvertone 7057 Audio "Cross-Talk" Problem? - Greg - 03-12-2018

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

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/637/M0017637.pdf

Thanks,
Greg

RE: Silvertone 7057 Audio "Cross-Talk" Problem? - slbradio - 11-14-2022

Hello from Pittsburgh! I was so happy to see your post as I just acquired the same unit. It's re-capped and the radio works. I have the schematics, but am curious if you've ever come across an owner's manual. Also:

Did you solve the crosstalk issue? I'd be happy to check for that on my end.

Mine did not come with its mic Icon_sad

. I'm hoping to find one. Do you know how it connects? I was guessing the recording socket, but all of those connectors seem to be populated.

Also, do you know if the motor has a ground wire running to it? I found a wire from the motor detached at its other end and am wondering if it came off of the rear ground connection.

Sorry for so many questions, I'm just thrilled to have found another owner. I'm happy to help on my end, too, if you're working on yours. Thanks!

RE: Silvertone 7057 Audio "Cross-Talk" Problem? - Greg - 11-17-2022

Hi slbradio,

Finally got around to this...

Yes there is a ground on the motor. The photo shows wires connected to a lug on the front pointing corner of the motor. The wires coming off of that go to to the switches controlled by lifting the tone and recorder arms. I show those connections in the next two photos. The connections, when measured, are connected to the chassis. I'm not sure where the connection to the chassis is made, maybe through the shields on the wires to the switches??? Sorry, too lazy to take it out of the cabinet.

Mine has a microphone input. It's a bayonet connector that's screws onto the bottom of the cabinet. I also added a photo of the microphone that came with mine. It's some Astatic model. I forget which. It still works and I believe it uses a crystal similar to those in the cartridges that disintegrate over time.

I do not have a manual for mine either. If you ever find one online, let me know. The controls aren't exactly intuitive. I need to review the schematic and make notes on how they work.

The cross talk thing still happens. I've given up on it and just tune the radio off of a station if I play a record.

I haven't tested the recording head. I need to find the cutter needle, it's somewhere. I think you can record on plastic covered Styrofoam plates. I do have some blanks, and recorded ones too. Interesting.

I did have the idler wheel refurbished (it was petrified). I also had the cartridge rebuilt and bought a proper stylus (diamond) at the same time. the steel needles are supposedly short lived.

I may do some work on the cabinet when I get a chance.

I got mine from a friend of my Sister. It came with the records and microphone.

I too am originally from near Pittsburgh, but ended up on the other side of the state...

RE: Silvertone 7057 Audio "Cross-Talk" Problem? - slbradio - 11-17-2022

Thank you! I greatly appreciate your help (especially the photos) and will keep you posted as I learn things.

RE: Silvertone 7057 Audio "Cross-Talk" Problem? - radiorich - 11-18-2022

Hello greg,
Great looking mic I have never seen tht mic before !
Welcome aboad slbradio.

Sincerely Richard
P.S. you might beable to add some extra shielding Greg .

RE: Silvertone 7057 Audio "Cross-Talk" Problem? - MrFixr55 - 11-19-2022

Hi Greg,
I just looked at the schematic from N/A, Link below:

http://www.nostalgiaair.org/PagesByModel/637/M0017637.pdf

There appears to be a switch component that grounds the detector plate for phono operation. This may be gummed up, broken, not wired correctly by a previous service person, etc. There appears to also be switches that determine whether the 6SQ7 or the 6SK7 are being used for the 1st audio amp. The 6SQ7 appears to be the 1st audio amp for the mic, where the 6SK7 is the first audio amp for the radio and phone. The 6SK7 is not commonly used as an audio amp, but my Zenith 6S52 chassis uses a 6H6 as a detector and a 6SK7 as a 1st audio. Sound from this radio is SWEET!

So bottom line is to trace all those wires from both the pickup tone arm and the recorder tone arm and ohm the contacts of the switch that is supposed to ground the diode detector plate of the 6SQ7.

Hope that helps.

RE: Silvertone 7057 Audio "Cross-Talk" Problem? - radiorich - 11-19-2022

mr fixr,
Great catch it could be as simple and tarnished switch contacts Greg ,
Sincerely Richard