Author Topic: Volume Question- SK53CW  (Read 1240 times)

AC207

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Volume Question- SK53CW
« on: February 19, 2018, 07:58:32 PM »
I've noticed on that the volume playing LP's is significantly lower than the output when listening to the radio or if I have a device (iPod, etc) plugged into the tape input.

Can anyone tell me if this is abnormal?  The volume from the changer is still fairly loud and seems equal between all three channels (this unit allows you to verify each of the three speaker channels).  If this is not typical behavior I'd appreciate your thoughts as to what I should be checking.

Thank you!
AC
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TC Chris

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Re: Volume Question- SK53CW
« Reply #1 on: February 19, 2018, 08:54:36 PM »
I'll post some best-guesses.  One is a failing phono cartridge.  But usually you get some distortion or bad-channel effects with that.  I don;t have schematic, but the preamp may have an extra stage of amplification for the phono input.  If so, check capacitors and resistors associated with that stage, and (is it a tube unit?) the amplifying tube for that function, likely a small triode or half of a dual triode. 

But really, if you get enough volume for your needs, you can always just ignore it.

Chris Campbell

AC207

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Re: Volume Question- SK53CW
« Reply #2 on: February 19, 2018, 10:09:54 PM »
Thanks, Chris.  No real distortion that I can sense though I do detect a bit of a low hum and I did notice that records are playing just a touch slow- steady, but enough to change the pitch of the song- though probably not enough for most people to notice.  I've just uploaded a short video I took on Saturday after I got it home.

Also, it is a tube unit. In fact I believe there are three amps.

https://www.youtube.com/watch?v=mUlVS8A6gyc&feature=youtu.be
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Motorola Minion

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Re: Volume Question- SK53CW
« Reply #3 on: February 27, 2018, 03:26:09 PM »
Usually Motorola Consoles record changers work as found but any nearly-60 years old V-M always needs a good disassembly and cleaning. Mine worked as found but soon developed issues as I used them.

The slowness could be the idler wheel has dry-shrunk or the motor bushings are worn, causing misalignment with the capstan shaft.

Volume issues could be the cartridge but the Sonotone 9t has no direct replacement. First to try is good cleaning of the compliance of encrusted dirt using alcohol and a mini brush.
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Dave

AC207

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Re: Volume Question- SK53CW
« Reply #4 on: March 01, 2018, 04:23:27 PM »
Usually Motorola Consoles record changers work as found but any nearly-60 years old V-M always needs a good disassembly and cleaning. Mine worked as found but soon developed issues as I used them.

The slowness could be the idler wheel has dry-shrunk or the motor bushings are worn, causing misalignment with the capstan shaft.

Volume issues could be the cartridge but the Sonotone 9t has no direct replacement. First to try is good cleaning of the compliance of encrusted dirt using alcohol and a mini brush.

Thank you- I'll take a closer look.
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electra225

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Re: Volume Question- SK53CW
« Reply #5 on: March 06, 2018, 10:12:33 AM »
A schematic may shed some light on your volume situation.  I can guess....


You might try cleaning the function switch.   As Dave suggested, clean the cartridge well.  Check any connections between the cartridge and the amplifier.  Check audio tubes.  Many times, there is an extra stage of amplification for the phono.  If the tube is weak, so may be the volume.  If it has tube rectifier(s) check those for output.  There may be a capacitor somewhere in the phono circuit that may be leaky and needing replacement.  Or a grid resistor that has increased in value.  Good luck.
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AC207

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Re: Volume Question- SK53CW
« Reply #6 on: March 06, 2018, 10:53:42 AM »
A schematic may shed some light on your volume situation.  I can guess....


You might try cleaning the function switch.   As Dave suggested, clean the cartridge well.  Check any connections between the cartridge and the amplifier.  Check audio tubes.  Many times, there is an extra stage of amplification for the phono.  If the tube is weak, so may be the volume.  If it has tube rectifier(s) check those for output.  There may be a capacitor somewhere in the phono circuit that may be leaky and needing replacement.  Or a grid resistor that has increased in value.  Good luck.
It is a three channel amp so I suppose that's a good possibility.  I'll have to see if I can get the schematic.  Don't think I saw it in the download section but worth looking again.

Thanks!
Adam
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Motorola Minion

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Re: Volume Question- SK53CW
« Reply #7 on: March 06, 2018, 11:30:47 AM »
The 1962 models were popular and need a schematic posted. Each chassis is stamped with chassis number like "HS-960A".

I just uploaded the 1963 :o- and if I have the 1962 for yours, will post in "downloads". That is too important not to share.
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Dave

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Re: Volume Question- SK53CW
« Reply #8 on: March 09, 2018, 01:34:03 PM »
The 1962 models were popular and need a schematic posted. Each chassis is stamped with chassis number like "HS-960A".

I just uploaded the 1963 :o- and if I have the 1962 for yours, will post in "downloads". That is too important not to share.

Yours uses 6BM8/ECL82 European-designed output tubes, which I am aware of but have never encountered. I have repaired several of the amps using 6V6 and 6BQ5 tubes only.

The radio and phono are via same pre-amplification stages (12AX7 tubes), so I would concentrate on the cartridge and wiring to the preamp selector switch.

A friend of mine (mostly a TV guy) supplied the Sams 568-10 which has all the schematics. Look under the "DOWNLOADS" tab once logged in, beware its 14 MB.
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Dave

AC207

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Re: Volume Question- SK53CW
« Reply #9 on: March 09, 2018, 07:45:15 PM »
The 1962 models were popular and need a schematic posted. Each chassis is stamped with chassis number like "HS-960A".

I just uploaded the 1963 :o- and if I have the 1962 for yours, will post in "downloads". That is too important not to share.

Yours uses 6BM8/ECL82 European-designed output tubes, which I am aware of but have never encountered. I have repaired several of the amps using 6V6 and 6BQ5 tubes only.

The radio and phono are via same pre-amplification stages (12AX7 tubes), so I would concentrate on the cartridge and wiring to the preamp selector switch.

A friend of mine (mostly a TV guy) supplied the Sams 568-10 which has all the schematics. Look under the "DOWNLOADS" tab once logged in, beware its 14 MB.

Thanks, Dave- really appreciate it!
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picard

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Re: Volume Question- SK53CW
« Reply #10 on: March 15, 2018, 09:32:16 PM »
I picked up a console with the exact same electronics but in different style cab on Monday. How did you polish that gold finish to get it so shiny?

AC207

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Re: Volume Question- SK53CW
« Reply #11 on: March 16, 2018, 12:11:40 PM »
I picked up a console with the exact same electronics but in different style cab on Monday. How did you polish that gold finish to get it so shiny?
It was like this when I got it.  However, the previous owner told me he used Howard's Restor A Finish on it.

Enjoy yours!
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