Strictly Idler - drive that is!

Why do they sound so good?

New GL55

I decided to try another GL55, so here it is as delivered.  Checked out the bearing and the motor, installed a metal idler wheel, and a Shure M55e in the cartridge slide.  The vtf spring was adjusted until the arm floated, then vtf was set using a weight on the headshell.  This first test was just to check the arm wiring, but from the first note it was obvious I had hit on a great combination.  Quiet background and explosive transients meant that Dire Straits sounded very good.  :) 

Examination

GL55 is the model number on the base plate.  In fair condition and will clean up ok.  I'm testing some modifications prior to the cleanup.

Just trying a Linn LVX in the hole left by original (cast metal, ceramic cartridge) arm. 

This picture also shows the classic Lenco drive system.  Original rubber tyre on the plastic wheel has been removed - very hard and very noisy.  The turntable was also very slow to start and get to speed with this old tyre.   These plastic wheel, rubber tyre idler wheels are the reason this marque has had such bad press for rumble.  Some models have an aluminium wheel with a thin rubber edge (see B55 image), these are much quieter.  This deck does not warrant the cost of a new idler so I decided to experiment with the plastic wheel.

Trying alternative 'tyres' - just using rubber bands works (and is quiet) but speed accuracy suffers.  The way it starts and gets to speed quickly is much improved.  The image right shows a thin O ring on top of the elastic bands.  This gives better speed stability, proving the concept, and is also quiet.  I think a one piece O ring of the correct size to fit the wheel would be an ideal solution.

Below Decks

This image shows the motor and bearing.  The bearing for the units with pressed steel platters is much smaller than the type used with the cast alloy heavy platters.  Notice the pressed steel platter, looks thin and light.  Ok for ceramic cartridges but will induce noise from the field around the motor into a sensitive magnetic cartridge.

Dismantling and Cleanup

This table will probably not be the last word in musicality, due to the lightweight steel platter and small bearing.  It should teach me about Lencos and dismantling them, so I am using it as a test machine.

I started the cleanup by dismantling the 55. (no dismantle number 55!  Aaaargh!)

I thought some pictures of the process would be useful during the reassembly procedure, and may be of interest to others about to work on Lencos.

 

Removing the motor involves 3 spring mounts. 

NB If the transit bolts are fitted they need to be removed also.  They have circlips fitted to prevent removal so remove those first.  Btw I always leave these transit bolts off when using a Lenco as they can short out the motor suspension and cause motor noise to be picked up by the cartridge.  See my GL72 page for more motor/spring info.  Now back to removing the motor -

Undo the nut and carefully remove the spring.  Follow with the other 2 mounts.  As you remove the motor and set aside don't forget the 3 more springs left on the posts. 

The 2 springs left are the same size and for the nose mount.  The smaller springs at the back go onto the posts of the main body mounts, with the largest ones under just before the nuts.

Motor


Update DEC 2005 ---------------------------- Please read this --------------------------

The information here is offered in good faith, but recent events have caused me to add the following caveat. 

Do not disassemble the Lenco motor without good cause, it is designed to work for many years without servicing.  The nose bearing particularly is a delicate item. I have had units where the adjuster is very difficult to remove, to the point that the force required to undo it is enough to destroy it.  The adjusting screw is hollow and contains a spring loaded pin that will be damaged by accidental cross-threading etc.  I doubt it is available today as a spare, so if broken the only fix would be a replacement motor. 

This strip down of the GL55 was a fact finding exercise, and any breakages would not be catastrophic for me.  Please do not treat your pride and joy Lenco in the same way.  It is highly unlikely that your motor needs servicing at all!  Now back to the story, but remember the context in which it was written.


The Lenco motor is very easy to disassemble (see note above!).  Just 4 screws on the back to remove and the rotor with coil assembly is off.

Then the rotor just lifts out of the coil assembly.  Notice the balance holes.

More than meets the eye!

The Lenco motor has a secret. 

If you've ever wondered what the adjusting screw on the nose is for, check out the pictures below.

Rear bearing.

  

The rear bearing is held in by a small plate on the coil assembly.  Once removed it reveals the spring loaded bush.

Nose bearing. (update Dec 2005 - see note above)

The nose bearing is similar, after undoing the adjusting locknut, the screw is turned out.  There is a circlip holding the bush parts in.  Remove this and the 4 parts can be removed.

 

The spring loaded bushes and the adjuster allow the end shake to be minimised.  Very neat. 

I hope I can replace it all !

Reassembly

While some pitting remains the deck plate cleaned up ok, I even managed to keep the stickers. 

 

Now the problem is to mount an arm capable of working with an acceptable cartridge.  The original arm need not apply.  I want to test this unit with a Shure M55e.  Robust low compliance mm.  I have another SAU2 so that would be ideal. 

Original arm position is way too far away from the spindle to mount the SAU2 directly.  Shame because the SAU2 sleeve fits perfectly in the mounting collar.  I would have to drill the plate about 1" in front of the old mounting to position the arm correctly.  So slightly different plan.  I have deliberately cut the board deeper to allow mounting an arm to one side.

Looks kinda strange but the geometry is ok.  The arm is set to hopefully minimise interaction with the motor position.

Testing

The first setup of arm mounted direct to the board, ended up with finding out my second SAU2 had a broken arm wire, and the direct mount made fine tuning impossible.  So onto Mk2.  I decided to use an arm board. 

Some pictures of the reassembly.  I used a Linn mounting collar and made a bush to fit the SAU2.  This combined with the adjustable arm board would allow me to try a Linn arm and others.

Pic left below - fine tuning the arm position, the pivoting arm board makes it easy.

The pic right below shows the grease around the speed slider, recommended by Jean.  Also the pivot to spindle measurement of the original arm mounting, looks like a Rega would have dropped in.  Bit ott though.

Extra earth connections to motor and main bearing.

Tried 2 plastic idler wheels and a metal one.  The metal one definitely quieter but belongs elsewhere.  Chose the quieter of the 2 plastic - still physically noisy but speed accuracy ok.  Need to source a supply of O rings to try that option.

First listen, I can hear the idler wheel in the room, and in the background between tracks, but on the plus side there is no hum.  This deck is very quiet electrically, I think the extra earth wires help.  Using my shelf liner mat the sound is detailed but bass shy compared to a 75.  Detail and clarity of image still better than my (very sad) Thorens.  Definitely Lenco with good starts and stops. 

I think more listening and fine tuning to do, but this deck has been worth the effort.  Maybe time to make some more layers for the plinth.  For that story click here.