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Topic: Old Zenith Turntable troubleshooting help (Read 8020 times) previous topic - next topic
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Old Zenith Turntable troubleshooting help

I just got my hands on an old Zenith Allegro HR596W, I'm assuming from the 70's. Seems to be in good shape generally but the turntable doesn't run. I took it apart and I can see the motor spinning but it's not activating anything. How should go about troubleshooting this?

    Also, this is the first turntable I've come across that doesn't spin freely when you manually push the wheel. It feels loose enough if I keep my finger on it and turn it around, but if I give it a good whirl and let go, it goes around at best one full turn. I don't see anything obstructing it underneath and I've applied some oil to it but that didn't do much. Is this a clue to something or are some turntables just like that?

Old Zenith Turntable troubleshooting help

Reply #1 –
By the way, it's direct drive.

Old Zenith Turntable troubleshooting help

Reply #2 –
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...the turntable doesn't run.  I took it apart and I can see the motor spinning but it's not activating anything... By the way, it's direct drive.
Direct drive means that the motor and turntable are integrated into one unit, or at least they have a common shaft...  So I don't understand how the motor can be turning without turning the turnatable????

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if I give it a good whirl and let go, it goes around at best one full turn. I don't see anything obstructing it underneath and I've applied some oil
  That does sound like "gunked-up" bearings.  Can you take it apart to the point of removing the shafts from the bearings?  If so, cleaning (perhaps with some sort of solvent) and re-lubricating should help.  If you can't get the bearings apart, something like "Liquid Wrench" or "WD40" might disolve the gunk in the bearings.  Typically, you have to get some solvent into the bearings and "work it in" by spinning the motor/shaft manually to loosen it up.

Old Zenith Turntable troubleshooting help

Reply #3 –
Quote
So I don't understand how the motor can be turning without turning the turnatable????


Well, I'm probably not using the right terms.  This is actually my first experience with a direct drive or anything this old.  I tried looking up pictures or diagrams but had no luck.  If you could point me to something maybe I could give you a better idea.  It does look like a motor to me though.  What's weird to me about it is even though that part is spinning as smooth as can be, none of the other parts "react"...I would just think I'd be able to detect some sort of strain as if the parts are trying to move but can't. 

Quote
That does sound like "gunked-up" bearings.  Can you take it apart to the point of removing the shafts from the bearings?  If so, cleaning (perhaps with some sort of solvent) and re-lubricating should help.  If you can't get the bearings apart, something like "Liquid Wrench" or "WD40" might disolve the gunk in the bearings.  Typically, you have to get some solvent into the bearings and "work it in" by spinning the motor/shaft manually to loosen it up.


Hopefully that's it.  It wasn't so hard taking it apart up to this point but it looks pretty complicated from here on.  But as long as I can feel a little more confident that it's not something mechanical and just needs to be cleaned up, I think I can handle it. 

Old Zenith Turntable troubleshooting help

Reply #4 –
Quote from: wellwellwell on
Quote
So I don't understand how the motor can be turning without turning the turnatable????


Well, I'm probably not using the right terms.  This is actually my first experience with a direct drive or anything this old.  I tried looking up pictures or diagrams but had no luck.  If you could point me to something maybe I could give you a better idea.  It does look like a motor to me though.  What's weird to me about it is even though that part is spinning as smooth as can be, none of the other parts "react"...I would just think I'd be able to detect some sort of strain as if the parts are trying to move but can't. 

Quote
That does sound like "gunked-up" bearings.  Can you take it apart to the point of removing the shafts from the bearings?  If so, cleaning (perhaps with some sort of solvent) and re-lubricating should help.  If you can't get the bearings apart, something like "Liquid Wrench" or "WD40" might disolve the gunk in the bearings.  Typically, you have to get some solvent into the bearings and "work it in" by spinning the motor/shaft manually to loosen it up.


Hopefully that's it.  It wasn't so hard taking it apart up to this point but it looks pretty complicated from here on.  But as long as I can feel a little more confident that it's not something mechanical and just needs to be cleaned up, I think I can handle it.


_Before_ you do any disassembly, take that digital camera and get a _lot_ of close-ups on how it is right now. Since digital pix are essentially free you have nothing to lose but it may help later on.

As for the mechanicals, Liquid wrench and WD-40 are not good things to use in a turntable. What you want to do is disassemble and clean out the old lubricants - which may more closely resemble mud at this point. For solvents isopropyl alcohol, MEK and Xylene work great but BEWARE that Xylene and MEK destroy some paints and plastics.  At work I use Nye oil II and Nye greases (all synthetics) but those may be too expensive and hard to get. A good light machine oil like for sewing machines would be fine. The only greases I use are the Nye so I don't have any recommendations but I DO know to NOT use Lubriplate as it separates. A bike shop might have some suitable greases.

Turntable main platter bearings are mainly sleeves with a ball bearing thrust for the vertical support. sometimes its 5 balls in a cage with a pair of flat wachers or just 1 large center ball on a flat surface.

G²

Old Zenith Turntable troubleshooting help

Reply #6 –
Howdy!  New member here.    This looks like a great site.    I participate on several other audio related sites, mostly for vintage audio gear.  That is a subject for another time and place though.  Just wanted to say hello and provide a little background.  More later.

I found Hydrogenaudio and this thread by searching Google for the Zenith Alegro HR596W.  I just finished restoring one for a thrift store where I volunteer as my time permits. They had a customer that really wants it but it wasn't working.  That is where I come in.  This one looked nice but had several issues, one of which was that the Turntable was completely frozen.  I serviced many of these in the past but this one was by far the most gummed up that I have ever seen.  All of the lubricating grease had turned to what amounts to an adhesive!  The platter would not turn at all.  To cut to the chase, the one that I have is a basic BSR rim drive changer with a Tetrad ceramic cartridge.  I would be very surprised to find a Direct drive TT in one of these units unless someone had swapped it out and added a preamp. 

To remove the turntable platter, first, pry out the aluminum trim piece that surrounds the spindle. Be careful not to bend it.  If you look closely you will see three small tabs that hold it in place.  Use a small thin knife to pry it out.  Next, remove the "C" clip from the shaft that holds the spindle.  The spindle itself will pull up and out by the way.  Keep your finger on that "C" clip as you remove it.  They have a way of flying off to places unknown when they are released.  Next, rotate the platter back and forth while pulling upwards.  Mine took a LOT of pressure to get it off due to the old grease / adhesive.  Clean all that old grease off with solvent and then clean and repack the platter bearing at the bottom of the shaft.  Relubricate with grease as others have suggested or something that has the consistency of vaselline.  Clean the rubber surface of the idler wheel with a little alcohol then LIGHTLY sand the surface to roughen it up just a little bit.  Reassemble and give it a spin. 

If you want to remove the entire turntable for more in depth servicing, remove the bottom cover then unplug the audio wires for the TT and unplug the power connector.  Next, flip the clips that are on the bottom of the two chrome colored tie-down screws located on the left rear and right front corners.  The TT chassis will then lift out easily.

If your 8-track player needs a new belt they are still available as are replacement needles for the TT.

Surprisingly, this thing has a decent tuner and it sounds pretty good, considering that it is what it is.

I will try to keep an eye on this thread.  let me know if I can help in any way.

Good luck!