Longevity of Technics suspension

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Luxman78
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Longevity of Technics suspension

Post by Luxman78 » 08 May 2019 16:00

After almost 40 years, is there something one would need to check/change/replace/oil to make the suspension effective again? Squeeze a Technics TT from the bottom and upper surface and you can feel how bottom part of the chasis is suspended from the upper half. When I release it, I feel bottom half knocking quite hard against its support. Is this normal or is it due to some spring being flattened or whatever?

Is something spent in the isolators 1 & 2?:
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lenjack
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Re: Longevity of Technics suspension

Post by lenjack » 08 May 2019 19:50

Some of us may recognize it, but give us the the model number.

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Re: Longevity of Technics suspension

Post by Luxman78 » 08 May 2019 22:46

I'm sorry, I thought most of these double chassis' were alike.

It's SL-Q202. But in general, is there any type of rubber gasket or anything that needs to be changed? It strike me as odd it be sitting on such a hard support, what's the use of double chassis' in that case anyway? You could make it out of five pieces, if they're sitting directly one upon another with no material in between, no decoupling will happen.

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Re: Longevity of Technics suspension

Post by lenjack » 08 May 2019 23:01

Advantage is that arm and platter are tied together on unified platform, separate and isolated from plinth, to make them highly resistant to vibration and acoustic feedback. This was exemplified on the original AR design which was extraordinary in this regard.

I do agree, however, that if the material has hardened or deteriorated to the point you describe, that the isolators are no longer working. I would be looking to rejuvenate or replace them. If no help here, try the Technics subforum if you haven't already. :)

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Re: Longevity of Technics suspension

Post by Luxman78 » 12 May 2019 11:42

All checks here but the felt. The felt is so squashed thin that the TT sits on the plastic rim of the foot. Bet that ain't right! :lol:

I have to change those on all four feet.
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Re: Longevity of Technics suspension

Post by lenjack » 12 May 2019 16:22

Looks like you've got a good fix on this,

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Re: Longevity of Technics suspension

Post by yarvelling » 15 May 2019 20:46

There shouldn't be anything needing replacement or adjusting with this suspension method.
With this suspension system, Technics anchored the main outer plinth to the four feet - the plinth containing all the control buttons, however, they also used those four springs to SUSPEND the main chassis - the bit containing the motor, platter, and arm, from those springs, which were anchored at the top to of the foot-pillars where they screw into the outer plinth.
So effectivley, the inner workings: platter, arm, and base-plate are hanging from the foot-pillars, giving good isolation.
Provided that no-one has unscrewed any of those feet/dismantled the turntable, and then re-assembled it incorrectly (there's always one 'silver' spring that needs locating correctly!), then the suspension should still work perfectly indefinately.....

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Re: Longevity of Technics suspension

Post by lenjack » 15 May 2019 21:01

Interesting. As you indicate, perhaps this was previously disassembled and improperly reassembled. Maybe reassembling again, but not screwing everything down tight would restore the suspension to it's former performance.

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Re: Longevity of Technics suspension

Post by H. callahan » 16 May 2019 01:08

Well, as far as i know these rubber cups are meant to dampen the springs and by that even further reducing vibrations of the subchassis (respectively vibrations going from the plinth onto the subchassis).
But those rubber caps can deterioate (well, actually rubber does deterioate anyway, but depending on storage conditions slower or faster) and then the damping of the springs will decrease - which again can affect performance of the tt, as a vibrating subchassis will shake everything attached to it (platter, arm etc.).

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Re: Longevity of Technics suspension

Post by Luxman78 » 16 May 2019 12:14

H. callahan wrote:
16 May 2019 01:08
Well, as far as i know these rubber cups are meant to dampen the springs and by that even further reducing vibrations of the subchassis (respectively vibrations going from the plinth onto the subchassis).
But those rubber caps can deterioate (well, actually rubber does deterioate anyway, but depending on storage conditions slower or faster) and then the damping of the springs will decrease - which again can affect performance of the tt, as a vibrating subchassis will shake everything attached to it (platter, arm etc.).
Thank you very much for the answer. Even the rubber still feels soft and thick so I don't think that's the problem. I'm having some sort of distortion so I'm trying to figure out what it is.

For this type of Technics TT one must find a flat surface, as it doesn't have extending legs to adjust if it's not in level, right?

Speaker cones are pulsating with quite some excursion even on empty parts of LP's (like the intro or between songs). When the tone arm is down on the record, cones really shake and I have a subsonic filter. Tone arm is tuned as advised by the manufacturer. It does so on all records I play so I don't think it's coming from the vinyl itself. They shake less when the needle is closer to the spindle.

I thought perhaps I got some rumble if the suspension wore out.

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Re: Longevity of Technics suspension

Post by lenjack » 16 May 2019 15:13

The suspension should feel like it's floating when you push on it. It shouldn't feel like it's bottoming. If you took it apart, put it back together, but don't screw it down tight as I mentioned above. What you're describing sounds like acoustic feedback, which this type of suspension should prevent.

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Re: Longevity of Technics suspension

Post by H. callahan » 17 May 2019 03:24

With these kind of suspensions there shouldn´t be something to adjust. Not screwing tight only should result in the feet not being tight on the plinth, resulting in less stable stand of the tt.

Luxman78 wrote:
16 May 2019 12:14
Thank you very much for the answer. Even the rubber still feels soft and thick so I don't think that's the problem. I'm having some sort of distortion so I'm trying to figure out what it is.

For this type of Technics TT one must find a flat surface, as it doesn't have extending legs to adjust if it's not in level, right?

Speaker cones are pulsating with quite some excursion even on empty parts of LP's (like the intro or between songs). When the tone arm is down on the record, cones really shake and I have a subsonic filter. Tone arm is tuned as advised by the manufacturer. It does so on all records I play so I don't think it's coming from the vinyl itself. They shake less when the needle is closer to the spindle.

I thought perhaps I got some rumble if the suspension wore out.
You´re welcome. As far as i see there is nothing to adjust with these feet, so yes tt should be leveled (with spacers under the feet for example).
Now i don´t know how critical the condition of the rubber cups is. I also have a tt (but not a Technics) which features the same construction on his feet and i only bookmarked this topic, in case you were replacing the cups. I wasn´t intending to post here, i only wanted to know if new rubber cups can make a difference.
But as then some incomplete information was posted, i decided to join in.

So i also don´t know how critical the condition of these cups are, but as your tt is about 40 years old, the rubber must have aged. The question is how much aging is needed to reduce performance.
As all i can do i guess, some questions:

Where is the tt placed?

Can you see the tonearm/cartridge vibrate when your speaker cones are pulsating?

Is the platter bent?

Is there a damping trough for the tonearm or has the tonearm some fluid damping incooperated?

What VTF are you using?

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Re: Longevity of Technics suspension

Post by H. callahan » 17 May 2019 03:52

I forgott:

Is there audible w+f?

If your tt has a lamp for "quartz lock" is on all the time or does it flicker?

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Re: Longevity of Technics suspension

Post by yarvelling » 17 May 2019 19:57

Luxman78 wrote:
16 May 2019 12:14
H. callahan wrote:
16 May 2019 01:08
Well, as far as i know these rubber cups are meant to dampen the springs and by that even further reducing vibrations of the subchassis (respectively vibrations going from the plinth onto the subchassis).
But those rubber caps can deterioate (well, actually rubber does deterioate anyway, but depending on storage conditions slower or faster) and then the damping of the springs will decrease - which again can affect performance of the tt, as a vibrating subchassis will shake everything attached to it (platter, arm etc.).
Thank you very much for the answer. Even the rubber still feels soft and thick so I don't think that's the problem. I'm having some sort of distortion so I'm trying to figure out what it is.

For this type of Technics TT one must find a flat surface, as it doesn't have extending legs to adjust if it's not in level, right?

Speaker cones are pulsating with quite some excursion even on empty parts of LP's (like the intro or between songs). When the tone arm is down on the record, cones really shake and I have a subsonic filter. Tone arm is tuned as advised by the manufacturer. It does so on all records I play so I don't think it's coming from the vinyl itself. They shake less when the needle is closer to the spindle.

I thought perhaps I got some rumble if the suspension wore out.

Download the service manual from here:
https://www.vinylengine.com/library/tec ... q202.shtml

read through it, and it'll show how the top plinth and sub-chassic go together. It will also indicate where/which corner, the 'silver' spring should be. It will also show where the wires from internal boards should be routed; likewise, the power/audio connectors should be routed out of the chassis.
This way, you can check to see that your turntable hasn't been opened in the past and re-assembled incorrectly.... I know how the incorrect placement of the suspension springs can completely ruin the performance on this, and similar turntables from personal experience! Likewise with wiring...if it fouls or is trapped internally, or is routed improperly to the exit points, then it can/will foul the suspension.

Oh....and you have checked - haven't you - that there are no transit/transportation locking pegs left inplace underneath the platter....? :wink:

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Re: Longevity of Technics suspension

Post by lenjack » 18 May 2019 03:22

Good points.

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