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Technics SL-J2 Cueing Problem

 

New member
Username: Flyguyfl

Post Number: 1
Registered: Jun-16
Any help appreciated. I have the subject turntable made 1984-1989 and recently put it back into operation thanks to this forum.
After cleaning the tone arm rail I find the system now cues 3/4 across the record. None of the cueing controls stop this. Ideas?
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18235
Registered: May-04
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I assume you mean when you start the automatic functions of the table, the arm moves into position for, say a 7" record.

First, read the owner's manual for the table. The linear tracking arm has an optical sensor which can be set for various diameter records. Make sure you have the setting correct to cue a 12" LP.

If that has already been done, then you probably need to have the table serviced. The optics may have failed on the table and, more than likely, if the table has been in storage for a few years, you'll want to have the entire tonearm mechanism cleaned and new lubricants applied. Over time the OEM lubricants will have hardened and this can lead to mistracking of the arm. Since linear trackers are connected to a servo loop which controls the horizontal motion of the arm, you'll also want the servo checked for accuracy. 1980's servos are extremely crude by anyone's standards to day and more often than not the arm was never located in an exactly perpendicular to the groove.

You'll have to find someone willing to take on a 30 year old table since shop manuals likely do not exist. There are no user serviceable items on this table beyond the most basic functions of, say adjusting tracking downforce. Without a manual and the proper test gear, I would not advise you take on servicing the optical or servo systems of this table.


http://www.vinylengine.com/library/technics/sl-j2.shtml





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New member
Username: Flyguyfl

Post Number: 2
Registered: Jun-16
Thanks. No place around here does any service on this old equipment. I was given the name of a place in Texas and another in NYC and I live in Florida. It may not be worth the cost when I could buy new.

I am guessing the optical sensor was affected adversely when I cleaned out the old lubricant.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18236
Registered: May-04
.

Value is always a prime concern when addressing vintage gear, particularly when the "vintage gear" was not really of a sufficient pedigree to warrant much thought in its day.

Linear trackers were never meant to be sold as inexpensive turntables IMO. The theories of tracking a variable pitch record groove via a linear motion tonearm are highly flawed IMO. It was sold to the mass market, low cost buyer as being perfected by the servo correction systems of the 1980's and '90's.

We are in these cases discussing what amounts to analog servos which lack the sophistication of today's high speed, and far more accurate, digital feedback systems.

(What I will say about linear tracking servos in the following will also apply to the speed control servos found in the mass market direct drive tables from the late 20th century.)



Unfortunately, one fact which is unavoidable when discussing a servo correction system is the unmistakable issue that something must go wrong before the servos can make a correction. "Wrong" is the switch which activates a servo.

In most cases, after first detecting an error, the servo will then, in an effort to "catch up", over-correct the observed error which means the arm has been moved into yet another incorrect position from which the pitch of the record groove is expected to make the final correction. That might be a good idea if the servo system wasn't sitting there waiting for yet another error to occur.

What this amounts to in real world terms for the life of a low cost linear tracking arm is a constant hunt and peck situation where the arm is virtually never in a correct position relative to the groove walls.

In the end, tracking errors (and speed consistency) are typically made worse (moment by moment) by such a servo system when compared to a well designed and well set up pivoted arm (or a basic belt driven platter).

While every "benefit" in audio has an equal "downside", the issues are even worse when discussing budget line gear.

As far as performance is concerned, stripping away the flotsam of "features" is typically the best route to higher levels of fidelity. During the latter half of the 20th c/ this meant resorting to the most basic fully manual tables using a belt drive mechanism. Though hardly perfect, such tables go a long way to addressing the most important issues of playing a LP with minimal errors.


If you've been working underneath the table while cleaning out old grease, it's quite possible you've boogered the cueing system. Of course, it's impossible to even guess over a forum but even a small bend in, or a shift in the position of, any of the levers beneath the table would result in inaccurate cueing.



You don't state a budget for a new table and cartridge but I would certainly advise you to look towards a new, and much higher quality, table than this Technics. You will likely give up some automatic features though I can't really say that's a bad thing when it comes to fidelity to the source.

The main problem with most of the affordable tables offered today is a lack of suspension. This means the table is highly sensitive to the feedback loop created by actually playing a record.

Turntables are a system of contradictions. What benefits the table in one respect is actually detrimental to its performance in yet another.

There are useful tips for dealing with non-suspended tables to be found in the archives of this forum. If you're considering, say, a Project or a Rega table, give those threads a good read.


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