Lab 80 MK II, Cueing Dilemma

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ChuckLab80+
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Lab 80 MK II, Cueing Dilemma

Post by ChuckLab80+ » 07 Jun 2019 18:17

Hello, I'm new to this list and this is my first post. I'm working on an old table I bought new in Germany in the mid sixties and brought home with me. It worked well for years and then was replaced with a Technics SL-J11D and sat collecting dust in my basement. With a renewed interest in vinyl, I've been working on it and with help of a service manual and info from the forum I've gotten it working somewhat and sounding good, but I could use some help. I've been through the dried up grease and idler wheel rehab and have come across a situation puzzling me. I have been through the set-up instructions to no avail. In the manual mode, the changer starts and the tonearm proceeds to the beginning of the album (12"). I grasp the cueing control tab and the arm settles gently to the record however, when I release the cueing tab, the tonearm raises again. It will not remain on the record unless I continue to squeeze the cueing control tab. (I have resorted to clamping it with a crocodile clip for workbench entertainment.) The tonearm has been balanced, The stylus pressure and tracking set, and the arm appears to be free. I've looked at it numerous times without success. I've been through the relevant forum topics and can't locate a similar situation for help. Thanks for the information and interest in these old turntables and any help you may provide

Pure_brew
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Re: Lab 80 MK II, Cueing Dilemma

Post by Pure_brew » 08 Jun 2019 13:40

Welcome! Hopefully you will get some more responses on this as I'm working on a similar issue - not fully resolved yet...

Have you checked the adjustments via screw on top of the tonearm and knurled nut under the table?

Now I don't know exactly how much spring back on the cueing bar you have compared to mine (Lab80), or how much there is on a perfectly working example - but I do not recall this being an issue after I first freed the mechanism - the tonearm was completely frozen in the up position as the old damping fluid had completely dried up.

After I freed it up with some penetrating oil and moving the cueing bar up/down a bit, the whole mechanism was completely free - but of course the tonearm would drop like a rock without sufficient damping fluid.

Then I followed the instructions on page *10, which discusses the fault "Pickup lowers too quickly on record cueing"

I had 100,000wt fluid available, which seems good for cueing speed but it may not be the correct wt - not 100% sure what that should be. (300,000/500,000wt?

In the end I wound up with a similar issue to yours - I can manually play a record and lower the tonearm without issue, but upon return, the tonearm strikes the pickup arm rest assembly. When I try to readjust the pickup height, there is enough of that spring back of the cueing mechanism that will not allow the tonearm to lower completely on the record. Close yet so far.

I'm going to revisit at some point.

*I did not follow the instructions in the part removal process and I do not think it is sufficiently cleaned. So my next visit to the issue will involve removing this part, cleaning/relubing":
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It probably goes without saying - but you should remove the stylus when you are working on this!

ChuckLab80+
United States of America
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Joined: 11 May 2019 23:31

Re: Lab 80 MK II, Cueing Dilemma

Post by ChuckLab80+ » 09 Jun 2019 01:06

Thanks for your reply.... My tonearm was completely free and the pickup and cueing heights were checked per the manual before I posted my issue. I did not have a hard cueing drop, in fact, it was somewhat slow and very gentle so I did not see any issue there. I just took another look and I believe that part of the operation works properly. I did have a frozen pivot (45, P26) for the cueing control cam which required heat from a solder iron to free. All that mechanism was disassembled, cleaned and lubed. It almost seems like the cueing cam is not raising the roller tip on the bottom of the cueing control tab as high as it could go. Possibly indicating wear or distortion on the cueing cam? I believe I will disassemble linkage in that area (45) to verify correctness. I don't believe there is anything else affecting the cueing cycle... Have I missed something? Thanks again!

DSJR
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Re: Lab 80 MK II, Cueing Dilemma

Post by DSJR » 10 Jun 2019 13:44

The cueing assembly is linked to the manual control tab, so there will be extra connections there (Diagram 12 in the service manual in the library here). The greases here are possibly solidified and if so, this WILL mess things up.

Granny sucking eggs so apologies - this deck has probably worked correctly for well over fifty years, so it's almost certainly dried out lubrication issues as the mechs were usually tank-like (just don't cycle the mech backwards as things may well break...).

ChuckLab80+
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Re: Lab 80 MK II, Cueing Dilemma

Post by ChuckLab80+ » 11 Jun 2019 11:00

Thank you for your comments, interest appreciated. As stated in my initial post, I did disassemble, clean, and lubricate all mechanisms and linkages as well as perform the initial adjustments per the service manual prior to thatl post. Going back to my 6/8 post, I did revisit the cueing control tab / cuing cam beneath the table and found a significant gap between them which I believed to be my problem. Seeing no other problem, I bent the cueing control tab up towards the deck until it pushed up the cueing control tab and returned it to its parked position. I also lubricated the sliding surfaces with a thin grease containing teflon. It seems to be a good choice. It now works as it should! I'll keep it on my bench for a while to test it out and enjoy my music while working on other items. Time for a new stylus... Thanks!

DSJR
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Re: Lab 80 MK II, Cueing Dilemma

Post by DSJR » 11 Jun 2019 18:53

The Lab 80 tonearm in good order is surprisingly capable these days now we don't track at 1g all the time..

Pure_brew
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Re: Lab 80 MK II, Cueing Dilemma

Post by Pure_brew » 13 Jun 2019 10:15

ChuckLab80+ wrote:
11 Jun 2019 11:00
Thank you for your comments, interest appreciated. As stated in my initial post, I did disassemble, clean, and lubricate all mechanisms and linkages as well as perform the initial adjustments per the service manual prior to thatl post. Going back to my 6/8 post, I did revisit the cueing control tab / cuing cam beneath the table and found a significant gap between them which I believed to be my problem. Seeing no other problem, I bent the cueing control tab up towards the deck until it pushed up the cueing control tab and returned it to its parked position. I also lubricated the sliding surfaces with a thin grease containing teflon. It seems to be a good choice. It now works as it should! I'll keep it on my bench for a while to test it out and enjoy my music while working on other items. Time for a new stylus... Thanks!
Glad you sorted it out. When I picked up the Lab80, the cueing/tonearm rest was about to fall off the turntable. Worth a revisit.

sberger
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Re: Lab 80 MK II, Cueing Dilemma

Post by sberger » 13 Jun 2019 20:20

So many little bugs that can disrupt regular functions on this great table, but once everything is refreshed and working properly, one can usually sort out a new issue fairly quickly. When it's running smoothly, it is easily my favorite table of 5 great tables that I own. The one that of all them makes me want to play vinyl non stop. It's that addicting.

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