Zero 100 tonearm movement

the jewel in the crown
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amagasakii
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Zero 100 tonearm movement

Post by amagasakii » 12 Feb 2020 00:52

Hiya,

TL;DR - I don't know what provides the "motivation" or friction for automatic tonearm start, and what to adjust or grease to fix it.

It's Garrard servicing week for me, it seems. I decided to tackle cleaning up the Zero 100 which has given me a new-found respect for how strong Garrard cement is. It took me several minutes of direct heat from the mini torch along with levering (more than I liked) and prying to free the Stop Lever from its post.

I've cleaned everything off and reassembled it dry for test fitting. All the linkages are free, the cam spins nicely; the Delrin parts of the cam are free. I'm a bit in the dark, however, because I don't have an example of how things should be assembled when it comes to the tonearm Friction Lever and Pickup Lever; these items were stuck and twisted when I got the turntable.

It turns out the tonearm was bound because someone had either forced it or rotated the Pickup Lever on the Pickup Spindle. I put everything back together in what appeared to be the "natural" position of the parts, in addition to consulting photos of similar "big chassis" Garrard models from this site and the parts diagram.

Manually running a start cycle by hand the mechanism moves the same as any videos I've watched. Nothing binds, the tonearm is lifted, but never swings over the platter. Crucially, it appears the start cycle is completed properly, as the Manual switch stays latched in "On". Auto-return works fine because the two faces I've circled in the second photo below seem to work as expected (Friction and Pickup Levers).

Three questions:
  • Autoslims have the Friction Link, Duals have the Steuerpimpel and Main Lever…what is performing the equivalent job in this mechanism? I don't understand what's meant to be grabbing the tonearm, and I haven't found a "theory of operation" section in any of the service manuals.
  • Does everything look to be in its correct position in these photos? Am I missing any springs or connecting rods? According to the parts diagram everything's here. Dare I fiddle with the black plastic adjusting nut on the Friction Lever?
  • What does the Retracting Lever I've circled in the third photo below do? I can't say that I've seen it move or really do anything thus far. Maybe once the tonearm does its thing?
Thanks for your help Hey, in the quick wins department, the speed control works perfectly, everything's de-cemented now, and I was able to bend the transit screw threads in the chassis plate back into shape without anything snapping. :)
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amagasakii
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Re: Zero 100 tonearm movement

Post by amagasakii » 12 Feb 2020 03:28

Edit: Spoke too soon. Leaving my premature post below, but there's definitely more going on here than I thought.

After more fiddling around I figured it out. The black screw, which I thought adjusted the tension of the friction lever, does the work. If it looks like a steuerpimpel, it's a steuerpimpel. :) Someone had cranked it down as tight as it would go.

T68
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Re: Zero 100 tonearm movement

Post by T68 » 12 Feb 2020 09:45

Hi!
Thought I had some pics of that area from my Zero (which fortunately have a fully working auto). But I see now that I did not. Hope some other member can help out.

I also have plans to video document the mech cycling when in working condition to have when/if my deck runs into problem. But haven't gotten around to it yet.

So I cannot be of much help here. Hope other members will provide better assistance.
Good Luck!

amagasakii
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Re: Zero 100 tonearm movement

Post by amagasakii » 12 Feb 2020 20:06

Any chance you could verify the range of motion of your tonearm? I was under the impression that all Garrard automatics "swung back" at the start of the cycle whether it's necessary when dropping records or not -- kind of a Garrard "signature" -- but I'm not sure if the Zero can/should. Youtube videos are inconclusive; they all show a bit of swing back, some more than others. (If nothing else, Youtube shows the vast range of what people consider "excellent condition".)

Here's the range of motion my tonearm exhibited last night; it can (and will) swing back at the start of the cycle, but that means it hits the overload spring at the start of the lead out.
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After much disassembly and reassembly of the pickup and friction levers last night, it occurred to me that someone might have fiddled with the tonearm set-down screw. I adjusted that (it had a lot of free travel), and now the tonearm can reach the label, but there's no swing back at the start of the cycle.

No matter how many times I tweak the faux-steuerpimpel, I can't get the friction right. If it's high enough to pull the arm into position it doesn't fit under the pickup lever. Low enough to fit under the pickup lever, no grip. :x Unlike the Dual system, there's nothing providing variable upward pressure, so I can't imagine how this works without a lot of brute force applied by the cam. Okay, enough rambling from me. :)

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Re: Zero 100 tonearm movement

Post by amagasakii » 13 Feb 2020 10:49

Good news: 1000 grit sandpaper taped to the bottom surface of the pickup arm provided the necessary friction for the auto cycle. Unless I'm completely misunderstanding this mechanism, it's basically an inelegant version of Dual's. I'll either scuff up the bottom surface of the pickup lever a la Dual's cross-hatch main lever or see how axle grease fares as an interface.

Bad news: Having watched this thing cycle over and over, I think there's more overall damage than I first expected, even in this very thread.

Far as my observations go, the two pieces circled below should pass like strangers in the night. On my Zero, they smack into each other, which means the tonearm is violently dragged towards the rest post soon as the stop cycle engages.
Either the tonearm tube has suffered a whack, or the pickup lever is bent. Either way, before I implement some Swindon Precision Adjustment™ (randomly bending things), does anyone have suggestions? In the last picture, green is the existing (apparently factory) bend; magenta shows my thoughts.
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DSJR
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Re: Zero 100 tonearm movement

Post by DSJR » 14 Feb 2020 14:52

First, there's a c clip missing in the pics above - bottom pic top right stud. Just thought I'd mention it.

I think the 'friction' element is above the deck plate and associated with the lift platform. On said platform and behind said visual lift area which the tonearm adjustable height thumb wheel acts on and under the main tonearm bearing 'block,' is a rubber 'pimpel' on a sprung lever (I'm not sure if you've ever mentioned this before). I think it's #20 (friction button).

In practise and on all models using this chassis, the friction button is there and doesn't release the arm fully until the stylus is well in the groove and the lift platform almost down, meaning that high compliance pickups tracking at 1.25 - 1.5g can have their styli highly stressed/pulled over by the lead-in groove (a disaster for some ADC cartridges I remember). Adjusting the tonearm height up as far as reasonably possible can assist, but it looks terrible so it's a compromise here. Not sure if additional friction is made underneath with the mech running, but follow the sliding plate and linkage as it moves towards the top left corner and 'guides' the metal-n-delrin round which in turn, 'urges' the arm back and forth.

Thinking about it, there must be added friction as the arm wouldn't travel in to the record index point - duh! :roll:

Do make sure the c clip is there, as a link missing an anchor can move out of alignment (added friction?).

Hope the above helps a bit...

amagasakii
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Re: Zero 100 tonearm movement

Post by amagasakii » 15 Feb 2020 06:06

Hey DSJR, fancy meeting you here. :lol:

The C clips have been on and off this thing so many times in the past week that I've taken to only reattaching them when absolutely necessary. I assure you, it's in a little pile on my worktop. ;)

Far as I can tell there's no #20 Friction Button here, but I think I'm looking in the wrong place so I'll double-check tomorow. I notice in Issue 3 of the service manual it's listed as "#19 Friction cap (not currently used)". All due credit, Garrard's isometric drawings are incredibly well done, so the fact it's just "hanging out" on its own in the drawing is annoying.
Thinking about it, there must be added friction as the arm wouldn't travel in to the record index point - duh! :roll:
:lol: I have spent a lot of time watching this thing trying to figure out what I'm missing, and I'm almost certain it's going to be something simple but not immediately obvious.

Today's "this should be easy" involved putting the platter bearing and cam back together after a cleaning. Nope; not easy. The smallest o-ring I can buy is too tall, so the top washer scuffs the underside of the cam and the auto trip lever misses the dog on the platter. #-o I'm fairly certain the o-ring is fine, but the cam is riding low.

Ever seen a top thrust bearing with a circular notch in it? No idea what this is all about.
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DSJR
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Re: Zero 100 tonearm movement

Post by DSJR » 16 Feb 2020 00:27

I've not dismantled the one on my Zero 100 so cannot say I'm afraid (I've got some proper Vactra slideway ISO 68 oil in lieu of Dual's renotac (same type of oil I'm told) so at some point, I'll bring the Zero back down and look at the bearing as regards cleaning and re-lubrication as this oil is 'clingier' than normal oil and I was told sinter-sleeve safe. If the old O ring is intact and not falling apart, I'd be inclined to put it back. The running marks are fine as long as there's not gauges where the balls have ploughed into them. If so, these washers could be rotated I suppose (I don't think organdonorparts do Garrards but haven't looked to see). Over lubrication can be worse than under, as the balls in the race should roll and musn't slide on the thrust washers.

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Re: Zero 100 tonearm movement

Post by amagasakii » 16 Feb 2020 01:08

The old O ring is nowhere to be seen, unfortunately. On other Garrards, the O ring seems to be slightly flattened, but I wonder if this is just what happens to rubber that's been under compression and soaked in grease for 50 years.

I've been pretty happy with winter weight chainsaw bar oil when it comes to spindles and platter bearings. It's heavy enough to stay put, even fairly well on open races like on the Autoslims.

I shimmed the cam with an additional washer, which raised it enough to clear the top thrust bearing and also engage the dog on the platter.

On to the next disaster!
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amagasakii
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Re: Zero 100 tonearm movement

Post by amagasakii » 16 Feb 2020 04:18

Found the friction button, at least!
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DSJR
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Re: Zero 100 tonearm movement

Post by DSJR » 16 Feb 2020 16:08

That's the one and I'm glad and thankful you've posted pics. I think, grey trim apart, that this basic platform assembly is used in all the decks of this chassis.

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Re: Zero 100 tonearm movement

Post by DSJR » 16 Feb 2020 18:53

P.S. You've done a great job cleaning all the old s**t grease off. The mech will run dry, but once working right (the tonearm bearing shaft being bent will almost certainly put the linkage attached at the bottom out of alignment as I think you've deduced), a very light smear of Gadus no.2 (if you have any left over from the Duals) or better probably, Superlube, will be beneficial. Just don't ladle it on as many do (including me in the past! and certainly Garrard's production line I think)

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