Author Topic: Motorola SK178-A3 console schematic?  (Read 346 times)

audiocarp

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Motorola SK178-A3 console schematic?
« on: December 30, 2016, 06:45:51 PM »
A customer has a console that appears to have the number "SK178A3" stamped on the Masonite back cover, although it could be "SA178A3"? This is a tube unit with 50HN5 output tubes. It was recently repaired by a local hi-fi shop, but it still has a problem where it will be completely dead and then suddenly come to life for a little while, but if you switch it OFF, and turn it back ON, then it will be dead, again. I'm thinking that the power switches are completely gummed up? Also, the AM is OK, but the FM is dead. I wasn't able to do any further testing, as it's still in the customer's home. (My shop is full.) I already checked the Sam's Index and came up zilch, so, if anybody has a schematic, it'd be greatly appreciated.

electra225

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Re: Motorola SK178-A3 console schematic?
« Reply #1 on: December 31, 2016, 12:11:57 PM »
I have an SK-176 with the 50HN5 output tubes, so I'm guessing mine is pretty close in layout to yours.  A suggestion I would make would be to thoroughly inspect and clean the function switch.  I have two stereos with the same chassis, and the FM mono position on both of them was dead.  The phono position on one of mine was shorted so the only way the radio would work was to have the turntable on at the same time.  THOROUGHLY cleaning the function switch was the cure on both of mine.  You might unplug the turntable power wire temporarily to see if that makes a difference.  My two Motorolas have the two separate large knobs for AM and FM and then the four smaller controls for loudness, bass, treble and function together.  Mine are fairly good performers for what they are.  The saving grace to mine is the Drexel cabinet.  I have the owner's manual for mine and it has the schematic in it.  Sorry, but I don't have access to a Sams for it.  Good luck.   :)
If it ain't broke, call me.  I can break it....

audiocarp

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Re: Motorola SK178-A3 console schematic?
« Reply #2 on: January 05, 2017, 07:43:21 AM »
Oh, thanks Electra225! Can I trouble you for the schematic to the SK176?  :)

electra225

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Re: Motorola SK178-A3 console schematic?
« Reply #3 on: January 05, 2017, 07:55:55 PM »
I would be happy to send you a copy of the schematic.  The problem I have is that the schematic is in the Midwest at my other place, and I'm in Arizona.  If you could hold off until April or so. I'd be happy to fix you up.   :)
If it ain't broke, call me.  I can break it....