Lab 80 - Manual Lever gets stuck?

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trigger_adam
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Lab 80 - Manual Lever gets stuck?

Post by trigger_adam » 22 Aug 2019 18:51

Hi:

New odd problem that seems that it could have a specific cause.

Out of the blue, my manual lever is resistant to pull all the way down. It's getting hung up physically. If I pull it hard enough it will then run an auto cycle, lift/drop the tone arm and reset itself. Then it works as expected.

It would appear that when a record finishes, the auto cycle maybe goes too... far?... and the gearing is going further than it should?

Maybe it's time for a grease?

Thanks in advance.

Adam

DSJR
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Re: Lab 80 - Manual Lever gets stuck?

Post by DSJR » 26 Aug 2019 19:18

Late reply...

The linkages around these tab controls are quite finely centred and sprung and if clogged with dried grease which ALL old Garrards suffer from, will tend to stick in place and cause your issues. Other parts of the mechanism are quite tough with strong return springs, but not the linkages all around the tab controls which have more delicate free movement. have a look around the service manual for pics and tips.

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Re: Lab 80 - Manual Lever gets stuck?

Post by trigger_adam » 03 Sep 2019 19:27

New symptom detail: This hanging up only happens if the tone arm has been dropped onto the record. For example:
1: I pull manual, record spins, I move tone arm all the way to the end of the record to engage auto-return, it's fine. Manual pulls down just fine next time.
2: I pull manual, record spins, I drop tone arm at the end of the last song, auto-return engages. NOW when I pull manual, there is some sort of mechanical hang up. The feeling is that something is misaligned now.

Now if I push hard enough, this hang up pops... manual goes down, and it's fine.

My guess is that some linkage between the auto-return/cue device and manual gets off. It's SO hard to see anything in there because I have to work on it upside down. I'm trying to follow the linkages in the manual and in real life, but I can't seem to find what's blocking it.

Make any more sense?

It's not a clog or dried grease. It's fairly recently serviced, and it works fine as long as the auto-trip hasn't engaged with the tone arm/stylus DOWN. Weird eh?

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Re: Lab 80 - Manual Lever gets stuck?

Post by trigger_adam » 08 Sep 2019 21:56

Ok, got this problem isolated, but not sure how to adjust.. but possibly it's just a spring?

The source of the jam is that the cueing cam - Diagram 11 - gets pushed too far under the cuing control tab extension that is under the unit. It's as if the friction has increased because the cam is situated just a 16th of an inch too far back. So, I have to pull the manual tab harder than I should to release the cam, and the mechanism releases pretty dramatically.

If I don't push the tab in all the way, using just about 10% less pressure, the cam doesn't get pushed that extra 16th of an inch and everything is fine.

This seems to be because either:

1: the cueing control tab release spring is weak and allowing me to push the button too far in, and thus allowing the cueing cam to pop too far.

2: The lifting lever spring is too weak? Allowing the whole cueing assembly to go too far?

3: There is something loose that's allowing the whole cueing assembly to move too far.

I can't find any adjustments for the cuing that would fix this over-extension. Any thoughts?

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Re: Lab 80 - Manual Lever gets stuck?

Post by DSJR » 09 Sep 2019 20:22

Silly suggestion perhaps?

Cueing height as against auto lifting height?

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SOLVED: Re: Lab 80 - Manual Lever gets stuck?

Post by trigger_adam » 25 Sep 2019 19:13

Ok, found the culprit.

This issue had been solved by a previous technician by inserting a small rubber pad against the chassis. That pad had come dislodged and slipped so it no longer prevented the cam from rotating about 3 degrees too far, allowing the cam to pop behind the roller on the cueing tab. See pic.

That explains why it suddenly started not working correctly. I cant really determine how to fix this mechanically or by any sort of adjustment. There's no documentation for this problem.
cam bumper.png
(1.99 MiB) Downloaded 26 times

Pure_brew
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Re: Lab 80 - Manual Lever gets stuck?

Post by Pure_brew » 26 Sep 2019 11:53

Good find.

Makes me want to look at the pickup rest - cueing lever/roller to see if it needs to be adjusted, cleaned and re-tightened. Though there likely isn't a lot of wiggle room. Like if it was seated a bit too far in the wrong direction, it would cause the cam to slip behind that roller.

Also, I wonder if the whole height of the cam is off just a bit because there is any dried crud somewhere on the shaft of all those stacked parts - or a missing washer that changed the height just a bit(?).

One other thing is that the cam seems to be scraping (or has scraped) the metal of the lower cam which seems odd. Perhaps this is a sign of the issue.

If the issue is that the cam just goes back too far and a rubber stopper fixes it, I suppose you could just stick something back there again. After all, it might not be the range of motion that is the issue, but that the cam somehow got bent which causes it to fowl in its normal operating range.

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Re: Lab 80 - Manual Lever gets stuck?

Post by trigger_adam » 26 Sep 2019 17:09

That's a good point. Maybe I'll compare the way it's built with the manual and see if there are any inconsistencies.

This garrard was serviced only a few years ago, cleaned and re-greased. So it should't be that. But I do see the scrape mark and that's something I hadn't seen before. That's a good indicator that there is something off for sure. I'll keep digging, but for now, she's cueing perfectly!

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