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 Post subject: Zenith MicroTouch 2G belt model - velocity trip sticking
PostPosted: Apr Tue 02, 2019 3:06 am 
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Joined: Apr Sun 16, 2017 7:57 pm
Posts: 145
I have a late 60s Zenith belt drive / idler model. X960 console.

The only issue I'm having, and it just started happening, is the stylus gets "stuck" near the end and won't trip. The stylus stays in position. It's like the tonearm index lever (part ref 88) is meeting a hair more resistance than it can handle when it encounters the trip link arm (part ref 101) and the needle gets stuck.

This is not my video, but someone posted a video on YouTube 8 years ago and the sticking issue he describes is similar to what I'm experiencing.

Please this video at the 35 second mark: ==>> https://www.youtube.com/watch?v=mS0FN28H52w

A.) I removed and cleaned the top trip pawl and bottom trip pawl (part ref. number 112 and 113) on the cam (they are now dry and move freely)
B.) I cleaned the trip link arm (part ref 101).

But after taking these cleaning steps, I still have the stylus sticking issue near the end of record. I bumped up the tracking force from 2 to 3.5 grams as a test to see if that was enough to trip and it wasn't. These are supposed to track at 2 grams.

There is another video where a 2g changer owner talks about the base of his tonearm getting gummy. I tried to remove the Tone Arm Yoke and Base Assembly (part reference 90), a cylinder at the base of the tonearm, but it has two set screws holding in place that don't seem to match up with any other set screws used throughout the turntable. I went through a number of screw drill bits (and types) trying to find a fit, but couldn't find the correct size/type for the mystery set screw dimension. So I couldn't get part 90 off to clean and lube it. Not sure if that is even the issue.

I noticed the underside of my chassis facing the cam wheel has "mini guide channel extrusion" in the sheet metal for the trip link arm to slide on as it moves toward the trip pawls. I wonder if that part of the chassis underbelly should be greased or oiled. Right now I don't have any lube on the entire trip mechanism (arm and pawls).

So it seems this sticking issue (probably a lubrication related cause, but am not sure) may be a common issue that crops up with these changers. It's probably something very simple -- as everything else works fine. If I manually move the arm to the leadout groove, it trips fine.

Any ideas on what the issue is and how to fix it?


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 Post subject: Re: Zenith MicroTouch 2G belt model - velocity trip sticking
PostPosted: Apr Thu 04, 2019 11:21 pm 
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Joined: Dec Thu 10, 2015 7:01 pm
Posts: 348
Location: Aurora, IL
I have a slightly older Zenith turntable of the Cobra type that I've noticed experiences this same velocity trip issue at times. Have also cleaned and polished the V.T. mechanism parts thoroughly and it worked fine on any record I threw at it for quite some time but as I expanded my record stash began seeing this problem occasionally. On observing the problem realized that when the velocity trip does not work it is on a record with very little available lead-out groove and looks just like the record in your video. Try it again with a different record that has a wider L-O groove and see if it always trips reliably on that record. It may just be that older records were less densely packed so had more L-O groove space. And makes sense to me that a compressed L-O track equals less velocity created which may cause a trip problem on some changers.


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 Post subject: Re: Zenith MicroTouch 2G belt model - velocity trip sticking
PostPosted: Apr Tue 16, 2019 2:10 am 
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Joined: Apr Sun 16, 2017 7:57 pm
Posts: 145
Thanks - good insight. I also wonder if with the later 2G changers if another cause is the tonearm itself getting gummy.

Anyone have any experiences with the 2G belt models sticking at end of record with the velocity trip (even when the trip pawls and trip link arm are dry?


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