Posted by Traddles on June 24, 2001 at 19:47:17

In Reply to: Goldring Lenco GL75 posted by willbewill on June 24, 2001 at 17:13:14:

Will,

Second hand, the (G)L 75's often come with one (or both!) of the antiskating weights missing. No problem, you can easily make a new one out of round brass stock (or a suitable small screw or nut works just as well).

The main problem usually is that the plastic horizontal axis bearing blocks have suffered--typically during (rough) transportation without the counterweights having been removed first (the arm sits in a funny 'tilted' position). You can make new ones out of scrap PTFE, or (easier) you can order new bearing blocks from Technical & General. You can also get a photocopy version of the manual from T&G. As the top of the arm post is open, the bearing blocks may also have about 25 years of dust in them. So, even if the bearing blocks are intact, it is probably worth your while to clean them--and the knife.

Before you start working on the arm, remove the headshell, the counterweights and the antiskating assembly (the corkscrew-like counterweight support comes off by pulling it gently from around the arm post (there's just a pin that locks it in position)). The platter is impressively heavy (and nicely machined!); you may want to remove it, too. You'll just need to remove the lockscrew on the side of the platter bearing first. Be very gentle when removing or reinserting the platter. And don't lose the single steel ball at the bottom of the spindle bearing! You may want to use this occasion to clean and re-oil these parts as well.

In order to get to the bearing blocks, you'll have to remove and disassemble the arm. First, though, you'll have to remove the cables from the connecting block with a soldering iron. At the same time, remove also the ground wire from the washer at the bottom end of the arm post (you'll need all the slack you can get in the wires when you remove inside of the top of the bearing post; usually, though, you can get by without having to desolder the ground wire from the arm tube). You will probably also want to add an extra ground wire from the chassis and arm to your preamp (originally, these were usually connected to the shield of one channel of the phono cables supplied with the unit).

There's a chrome plated collar encircling the hole through which the arm post goes, which has a single setscrew that holds the arm post in place (this is the VTA adjustment). If you have access to the appropriate tools, it is a good idea to add two more tapped holes to the collar (120 degrees apart) and lock the arm post in place with three setscrews (I strongly recommend Allen screws).

The vertical axis revolves in two ball bearings, as you'll soon find out. Remove the nuts at the bottom of the arm post. Now you should be able to separate the main part of the arm post and the top. There's a screw underneath the arm that holds the inside of the top of bearing post in place. Once you have removed this screw (and its U-shaped washer (tweezers come in handy)), the inside of the arm post (which is really a piece into which the bearing blocks have been cast) should come off by pushing it gently. Be extra careful with the wires! If you're replacing the knife edge bearing surfaces with homebrew parts, you may have to disassemble and reassemble the arm several times to get the heights exactly the same. If you run out of patience, you can always do the fine tuning by shimming the cartridge.

The most difficult part of the whole thing is tightening the vertical axis bearings. You will want to have it free with absolutely no play. Several iterations are usually needed to accomplish this, and the final test will be when you adjust the antiskating.

The rear part of the arm, which holds the counterweight, is flexibly coupled to the rest of the arm (it is _not_ broken). It acts as a dynamic vibration absorber, an ingenious mechanical device pioneered by J.P. Den Hartog in the 1920s.

To balance the arm, install a cartridge and insert both the main counterweight and the small VTF counterweight. Set the VTF counterweight in its rearmost position ('zero'; the scale on the VTF arm is graded in 0.5-gram increments--the scale is pretty accurate, if you balance the arm carefully). For front-to-back balance, the arm should stay put when it's free, it should not move up or down (obviously). The main counterweight has a hole which is off-center to allow the adjustment of the lateral (side-to-side) balance. Put the front of the arm loosely (do not push it down) on the arm rest and lift the back of the arm slightly (use a sharp straight piece of metal on the underside of the arm for lifting). You can immediately see whether the arm is laterally balanced (if it's not, it tends to tilt) and, if necessary, compensate by shifting the main counterweight sideways and locking it in place with the appropriate thumbscrew.

The antiskating is adjusted in the 'normal' way (use a test record!). If the vertical axis bearings are dirty or have a lot of friction for some other reason, you may not be able to work with the settings in the manual. If it appears that you'd need a 'negative' antiskating setting, the vertical axis bearings have definitely too much friction.

The capacitance of the original cables (within the arm) is about 90 pF.

The (G)L 75 is a very underrated turntable. It is popular mainly among 78 enthusiasts, who appreciate the large speed adjustment range. Just like the Garrard 301/401, it benefits from a heavy plinth (originally it was available with an optional spring-loaded plinth made of veneered MDF). I have a Goldring 1042 cartridge on my L 75, and it always manages to amaze me when I run side-by-side comparisons with my 'better' turntables.

I hope this is of some help.

Trad

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