LENCO - GL75 Project

[brian2957]

No stone ( or potential source of vibration ) being left unturned Andy I doubt anyone has been through a GL75 like this before . Again a treasure trove of information on how to max out this turntable . The results of this experiment will be watched with interest as some can be applied to the original GL75 . I'll be seeking out some sorbothane sheet and making the appropriate parts for mine .

[CornishPasty]

All those open areas under the top plate as in the last pic need filling in either with resin or bonded aluminium plate. This will give the top plate more contact area with the plinth and will also strengthen and dampen that lively top plate. You'll find you won't need to tighten those long bolts within an inch of their lives either as the plate can't flex when the voids are filled in.

[Wakefield Turntables]

Ralph, your suggestions make good common sense but is this a mod that you have done yourself and can honestly say has made a big difference? If I was too do another build I'd go down the "pan" route and circumvent any need for filling any spaces and maximising surface area to the plinth. The reason for me anally assessing (I bet that conjures up some rather nasty images ) each component is so that I hopefully negate and dissipate any vibration from the top plate into the plinth. We also have to think about vibration getting into the plinth from the floor / hifi rack etc so I'm comtemplating a sprung based board for the '75 to sit on. I'm doing a little research when time allows into this area.

[CornishPasty]

Andrew, the first two I built had all empty spaces filled in but I used acrylic because that what I had at the time. It simply gave a flat surface to sit on the plinth rather than hollow spaces. I can't say it makes a difference because I've never tried it without. When I started putting decks together for others I read everything I could about the Nantais decks and just followed his example where I could. Then I started using the 69/72 chassis because it didn't have that pan and made things so much easier but I also started splitting the bearing so things changed somewhat and I ended up making my own chassis. I really need to PM you. Apologies but I've been caught up in a lot of things just lately and I do need a couple of hours to sift through stuff. I will PM you though I promise.

[Wakefield Turntables]

Tonights Update - The "Reference" Lenco Pt IV - More vibration supression.

The idler arm park got my attention tonight. It's held onto the top plate with a single threaded screw and a nut but is yet another conduit from vibration travelling down the power leads from the motor into the on/off switch. It makes sense to couple the idler arm park when one considers the idler arm park touches the on/off switch and the on/off switch is located approx 1" from the idler arm park nut/bolt. Improving coupling to the idler arm park nut/bolt should reduce vibration getting into the idler arm park itself and hopefully from getting into the idler arm retaining bracket. Whilst these components don't strictly make any contact with each other near the idler arm at the idler arm retaining bracket I still think its a good idea to try and stop any vibration up into that neck of the woods . This little mod on it's own probably does nothing but it's the cumulative effects of all the mods where I'm trying to make a difference.

The original idler arm park screw was quite small and needed replacing. I purchased a selection of very small nuts and bolts and some 3mm rubber gromets from Maplins ages ago when I was messing around with my SME 3012. So I added a simple gromet under the bolt head (Picture 1) and then added a gromet to the underside of the bolt along the threaded shaft, I salvaged the original retaining nut and added a little tension with a pair of small mole grips. A very small tweak which improves the coupling of the idler arm park to the top plate.

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I really must do something with the on/off switch on the underside of the top plate. I think I need to email a fellow AOSer for some help. Details to follow!

As always fellow AOSer's

[Wakefield Turntables]

Tonights Update - The Reference Lenco Pt V - On/Off switch solved!

No pix tonight as I'm pretty knackered. Just a few words. I decided to remove the on/off switch from the underside of the Lenco top plate, well it had to come off anyway so tonight was a good a night as any. I decided to have a look in my set of spare Lenco parts to see if i could disect the switch whilst still having a spare sitting around. I managed to find an old switch and opened it up. It's a pretty simple design the on/off switch is simply a rocker switch sitting on a spring when the spring is flipped it creates a electric path with a little metal roller in the switch casing. Two wires come away from the switch which then go into the Lenco motor and a supressor Capacity which stops clicks into your speaker amongst other things. So really all I need to do is get my soldering iron out desolder the old bell wire attached to the on/off switch and replace with something a little better quality and more importantly slightly longer in length. The supressor cap can be left in place. I intend to mount the on/off switch to the front of the underside of the plinth and this way the deck can be switch on very easily whilst a full 90mm worth of birth ply sit between it and the top plate. This solution neatly removes vibration from the top plate but potentially introduces it to the underside of the plinth where the new Jolyon bearing is going to be mounted. So, position of the on/off switch has not been finalised but I may mount the on/off switch on sorbothane to try and supress further vibration into the plinth and the bearing. Ah, decisions, decisions.....The solution to this little problem as a lot easier than I expected. Thanks also go to Jez of Arkless electronics for some helpful advice. Cheers.

Until next time (And some pix I promise)..

[Wakefield Turntables]

Tonight Update - The Lenco Reference Pt VI - Getting switched onto the Lenco.

Tonights bit described my final fetish with the on/off switch. I decided that the switch had to be shifted from so close to the bearing or the idler arm it's an invitation to transmit vibration from the motor into the top plate. I decided to play things safe and dig out an old switch from my spare Lenco and I also decided it needed slight modding.

I decided to keep the original and more importantly working switch (the black one) and replace the original wiring on the old switch with something longer which meant I could move the switch some distance from the bearing. I also made a simple sorbothane base so that additional vibration would be absorbed into the sorbothane before going into the plinth.

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The next stage was to try and decide where to mount the switch. I initially decided that the front of the plinth would be a good idea but then I realised it looked pretty $#!+ , as you can see.

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I then realised that the switch was still quite close to the bearing so I then decided to mount the switch to the left side of the deck behind one of the feet and as you can see the switch is completely hidden when you look at the plinths foot.

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The underside of the top plate is now looking more optimised and less cluttered.

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I have now removed an additional two screws and washers from the underside of the top plate which have potential to rattle and vibrate on the top plate. I suppose I could fill in the holes from where the switch used to be situated and indeed I may do this to stiffen the top plate a little further but that would mean more time spent on repairing the paint work we shall see. I'm now in a position where I shall be turning my attention to the idler arm and it's linkages and other gubbins and then I think I've finished with all my isolation work. It looks like the idler arm is to stripped down, rebuilt etc and then I'll be fitting the Wer stability mod to rid my arm of the slight oscillation it suffers.

As always until next time...

[brian2957]

Are you now operating the switch like a little toggle switch Andy ?

There isn't much left to vibrate now is there

I'll be interested to see what your plans are for the idler assembly as I'm not sure there is much there to cause vibration ( or is there )

The Werner mod for the idler wheel certainly worked on mine and removed a slight wobble which couldn't have been doing the SQ much good .

Any word on the Jolyon bearing ? This is another mod which is on my radar .

[Wakefield Turntables]

Are you now operating the switch like a little toggle switch Andy ?

There isn't much left to vibrate now is there

I'll be interested to see what your plans are for the idler assembly as I'm not sure there is much there to cause vibration ( or is there )

The Werner mod for the idler wheel certainly worked on mine and removed a slight wobble which couldn't have been doing the SQ much good .

Any word on the Jolyon bearing ? This is another mod which is on my radar .

The switch is basically a toggle switch but the idea is it switch on the power using the relocated on/off switch and then introduce the idler wheen via the on/off switch on the top plate. I don't need to do this but I have heard that the idler wheel can "kick" if it's left in contact with the motor spindle. I'll be doing some testing to see if this actually happens on my deck. I have seen some vids on Youtube where this pheonoma exists. The idler arm is probably going to be very prone to vibration due to the locking plate for the idler arm being fixed to the top plate. I have mitigated some vibration away from the idler arm by relocating the on/off switch and decoupling the bearing. As you can see I've improved the coupling of the idler arm park. I'll have to have a proper look over the next few days to see if anything further can be done. I'll probably be filling some holes in the top plate to try and improve its stiffness and I'll probably restrip and respray the whole top plate (it's quite easy to do) so that I have a much better finish than my first attempt. I still havent heard anything about the bearing and I'm quite thankful to be honest as I have a little breathing space to get all these little mods sorted. I still have a lot to document. There is still the tonearm and cartridge to think about, I already have a lot of the stuff ordered which means I can crack straight on when the time comes. The idler is coming next so keep tuned.

[Wakefield Turntables]

Tonights Update - The Reference Lenco Pt VII - Idling my time away.

The idler arm is perhaps one of the single most important components on the '75 so I decided that mine needed some much needed TLC. I have done a full strip, clean, re-oil and re-lube (oo-er). This maintainence work is needed to keep the idler wheel spinning as freely as possible whilst maintaining the plasticity of the idler wheel. I did intend to measure the idler wheel for the Wer modification but I could not find a 2.5mm or 3.00mm drill bit to measure the diameter of the wheel, this is annoying and it means I need to spend a little time walking to B&Q tomorrow to buy them , never mind at least the '75 is progressing.

Its getting colder in the garage so I don't see why I should suffer when I have valves and beer in my listening room, so the cleaning products got taken upstairs.

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A very dirty idler wheel with old oil and gunk.

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Same again lots of dirt and debris from over 40 years service spinning 12" frisbee's


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Now a little spit and polish and things start to look a lot cleaner.

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This looks more like it!

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