Turntable Blues...

[Haselsh1]

A little while back I decided to check the bearing oil on my Thorens TD160 Super fitted with an Alphason Xenon MCS tonearm. The Thorens was bought near to the beginning of 2009 and has been used throughout the year but on removing the bits and pieces that make it up, I discovered that there was actually no oil in the bearing whatsoever. The bearing looks new and very shiny so I'm hoping there is no damage, however, now that the thing is back together, there is a loud hum and clunking and knocking from the arm when it is moved. OK I may well have dislodged something and I will indeed check it out soon but; to the question...

I was contemplating at some point a rewire of the Alphason or a brand new Jelco SA-750D tonearm. At present, the system is used with a Denon DL160 but my wish for sometime next year is to fit a Dynavector DV20XL. Your thoughts please...???

I already have the thoughts of HiFiDave and take them very seriously but I'd like a wider opinion.

This near tragedy has put on hold my purchase of a Croft power amp...

[DSJR]

Use a good few drops of EP80 oil (or EP90 if the inner hub wobbles in the bearing (early two-bush ones could, although mid period ones with thinner spindle snd deep bushing didn't). The former oil is an exact replacement for the "Crown" oil supplied when new I've read and certainly smells similar.....

Oh pooh, I typed the text beloe before it clicked you have a third party arm fitted... make sure the arm lead is plugged into the pillar socket properly. There should be a separate short earth lead which should be connected to the chassis point nearby, where the sub chassis earth wire is screwed. I used to gently roughen the surface of the eyelet tag and solder the arm earth directly to the eyelet as we did with the LP12. I have no photo's but hopefully this should be obvious when you look underneath.








Now, the TD160 had yuchy earthing and should be ammended as follows... Look at the signal wiring strip. The leads from the tonearm should be obvious and you should find the black arm-earth is connected to the middle terminal which is riveted to the chassis top plate. There used to be a linking wire IIRC which connected the chassis (and soft sub-chassis wire) to one of the signal screens. I suggest you cut this link and solder a fresh earthing wire to the earth tab, taking this out to the amp or mains plug as the master earthing wire for the deck, keeping the signal screens for signal return only.

Hope this makes sense to you. Linn's instructions (for legal earthing) were that the deck should be earthed to the mains, the arm to the deck and any extra earthing wire connected to the amp (or not, if there's a hum loop). The TD160 has a two wire mains, so a separate earth wire should be created and the link to signal screen cut out... (My Dual 701 was originally earthed this way and this was the first thing I dealt with...)

[Rare Bird]

Is the clunking/Knocking actually coming from the arm or is your suspension set too low, this would make the springs over springy & cause the platter to knock againt the metal top, & or the motor pully knock against the platter!...too high the springs have no spring as such & cause the sub chassis to knock against the top!, odd an oil change would do this tho.is something jammed fouling the suspension?

[Haselsh1]

The clunking and knocking sound is only when the arm is moved and is coming through the speakers so is amplified.

[Rare Bird]

Doesnt sound like an electrical problem..As you've had the platter off & sub platter out is the belt catching on the pulley guide or anything? The motor pulley on these are very close to the platter inside aswell..Any front on pics of the deck?

[DSJR]

If it's coming througfh the speakers, it probably has to be an electrical problem in my experience, unless you've knocked the stylus or summat. Sounds like an earthing issue to me as all sorts of noises happen when the arm tube isn't neing earthed correctly...

[Haselsh1]

DSJR I think you're right but I've just spent a half hour or so redoing some of the Earth wiring in the turntable and it's made no difference. The low hum is still there and I've also noticed that if I move one of my hands near to the cartridge, the hum increases considerably.

[DSJR]

Check wiring under the arm and also headshell connections.

Low hum on both channels? Got to be an earth wire come loose. Sorry, I've only ever fitted cartridges to Alphason arms and have never fitted a new arm on to a deck...

I'll always have the arm though if you get fed up and need to chuck it out...

[Haselsh1]

You know, I was seriously considering a Technics SL1210 Mk5G and this nonsense is doing nothing to make me want to keep the Thorens...!!! I feel an ebay moment coming on....

[hifi_dave]

I don't see why it should be the Thorens, the arm is independent of the TT so far as the signal is concerned. The problem is a mechanical one in the arm and/or a wiring prob. Hum when you place your hand near the arm is indicative of an earth fault, so check that out thoroughly. It might well be the earth for the arm metalwork, so try attaching a wire from the arm tube to the amplifier casework or earth terminal and see if the 'hum' goes.