Who has re-wired a SL1200 MK2 arm?

[Laudanum]

Please refer to the picture in the attached link:

For anyone who's re-wired one themselves, where does the black wire that is attached to the right side of the pcb with that ring terminal go to?

Also, where is the ground wire running with the external cables connected? Underside of the PCB?

http://i182.photobucket.com/albums/x105 ... xposed.jpg

[cafe latte]

Hmm strange I dont remember that black wire that is is on the right going off elsewere . The thin black wire is the arm ground and that is connected to the inside of the arm so leave that in place when you rewire and just fish the others through. Tie a bit of fishing line to one of the other wires with a small knot or it will get hung up. If it gets stuck pull it back and try again , but dont force anything. Put a headshell on the arm stub with silver foil between the conection, this is both a reference and a heatsink for later.Mark the collar relationship with the arm wand, now remove the tiny screw near the arm collar on the arm underside. With all the arm wires desoldered from the board EXCEPT the black one gently remove the arm collar, in doing so you will pull through your fishing line and other wires. Now when the fishing line is through at the collar end tie your new longer(easier) new arm wires to the fishing line (again with a small secure knot) and gently pull them back the other way. It can be easier if you remove the tiny screw at the other ends of the arm wand before you start as there is less to feed and you can see better what you are doing, but be careful of the black earth wire dont pull anything too hard. When your wires are through solder them to the arm collar. Get good quick heat to the terminals as you dont want to melt the plastic, the headshell and foil should make sure you dont though. I cut little sections of heatshrink and slide them before I solder on the wires so I can slip them over later to prevent any shorting. When it is soldered and you have checked each connection for continuity, add a pinch of cotton wool to both ends of the arm tube for internal damping. Dont go mad just enough to stop ringing but still letting arm wires move. Reinstall the arm wand screws. I made a copy of the metal arm plate with a dremel tool and fitted rca sockets to that, I then soldered my longer arm wires directly to the sockets. I removed the tiny board and screwed the external earth to the hole it was in that held the board in place and the earth arm wire I soldered directly to that wire. Not sure were the other wire goes, but as long as they are all connected to earth it will not matter.
Regards
CL

[Laudanum]

I've read that the arm tube ground can be seen if you remove the arm tube at the base end as you described. Do you know exactly where and how it is connected?

As far as wire pulling, I shouldnt have a problem with my high E string method. And I already planned on attaching the headshell as well as using a small heatsink when soldering to the collar. Ive read the elswhere.

Guess I'll see what's in there when I open it up. Im not in a hurry.

Picked the table up today from an acquantince. Missing the overhand guage which I dont need and the extra arm weight which I dont need. I figured both were gone. Other than that, it's a 9 out of 10 cosmetically and works perfectly. Event the dustcover is nice, just those tiny spider scratches from dusting, still clear. Really great condition and it looks like it's not very old production. Is there any way to date them? It was a steal. Actually it was a trade for an item that I paid $220 for so ... nice deal.

Thanks for the info. If you know where and how the other end of that ground wire connects inside the arm, please chime in.

[kcdonahue]

The black ground wire in the picture connects to the closest screw that holds the pitch slider in place.

The thin black wire is attached to a press fit aluminum piece that is just inside the tube where it meets the bearing assembly. If you remove the two screws at the base of the arm it will likely fall out.

KC

[Laudanum]

The black ground wire in the picture connects to the closest screw that holds the pitch slider in place.

The thin black wire is attached to a press fit aluminum piece that is just inside the tube where it meets the bearing assembly. If you remove the two screws at the base of the arm it will likely fall out.

KC

So does that ground from the slider need to be connected with the external ground wire or no?

And the arm tube ground ... is it in there in a way that it can be replaced easily if I remove the arm tube to make rewire easier? Or is it best not to remove the tube?

Thanks

[cafe latte]

The black ground wire in the picture connects to the closest screw that holds the pitch slider in place.

The thin black wire is attached to a press fit aluminum piece that is just inside the tube where it meets the bearing assembly. If you remove the two screws at the base of the arm it will likely fall out.

KC

No it does not fall out when the screws are removed (at least on my arm)as I have had my arm completely apart and the wire stayed put

[Laudanum]

The black ground wire in the picture connects to the closest screw that holds the pitch slider in place.

The thin black wire is attached to a press fit aluminum piece that is just inside the tube where it meets the bearing assembly. If you remove the two screws at the base of the arm it will likely fall out.

KC

No it does not fall out when the screws are removed (at least on my arm)as I have had my arm completely apart and the wire stayed put

Thanks. Guess I'll know what it looks like exactly when I open it all up.

[Laudanum]

Thanks for the input guys. Re-wired it yesterday. Time consuming but not a difficult rewire at all. Workmanship is good but the stock wiring really doesnt do the table any sonic favors. I believe it's the tinned, stranded internal arm tube wiring more than the external coax (which is decent enough) or even the PCB used in the arm base. My go-to tonearm wire (and cable) made for a very worthwhile sonic improvement (and Im not a huge wire/cable guy). Most notable was taming what I found to be a harsh, gritty treble. But other improvements all around. Well worth the effort. Thanks again for the tips gents.

[Dezie]

I did mine 2 weeks ago and can report the same improvements. I also filled my arm with cotton wool which has completely deadened it, as least to my ears. By way of comparison, I previously upgraded the phono and headshell wires. Both made a difference but the arm rewire made as much of a difference as the other two combined. My tip - undo the screw in the top of the tonearm pivot housing and completely remove the arm from the housing. This makes threading the wire very simple and reveals the mystery of the earth wire
Btw, I have no previous soldering experience and no knowledge of electronics.... Just adventurous with a good set of ears!!
Go on do it... The results are well worth the effort. And you'll no longer crave an RB250 arm
Final point - be careful when you tighten up the pivot screw. Overtighten and your arm won't track properly. Undertighten and it has too much play. Took me a few minutes to work that one out... Hope this saves you the trouble.
Enjoy your music!!
Dezie

[cafe latte]

I did mine 2 weeks ago and can report the same improvements. I also filled my arm with cotton wool which has completely deadened it, as least to my ears. By way of comparison, I previously upgraded the phono and headshell wires. Both made a difference but the arm rewire made as much of a difference as the other two combined. My tip - undo the screw in the top of the tonearm pivot housing and completely remove the arm from the housing. This makes threading the wire very simple and reveals the mystery of the earth wire
Btw, I have no previous soldering experience and no knowledge of electronics.... Just adventurous with a good set of ears!!
Go on do it... The results are well worth the effort. And you'll no longer crave an RB250 arm
Final point - be careful when you tighten up the pivot screw. Overtighten and your arm won't track properly. Undertighten and it has too much play. Took me a few minutes to work that one out... Hope this saves you the trouble.
Enjoy your music!!
Dezie

Really only a pinch in each end of the arm is needed otherwise you will increase the efective mass and restrict arm wire movement. Also I would not advise messing with bearing screws as they are set critically at around 0.5 micron clearance, not something you can guess. If you remove the screws at either end of the arm tube though it makes threading the wires much easier and that is all that is needed.
Regards
CL

[Dezie]

Thanks Cafe. I dont have any knowledge or experience in such things but Im going to challenge what youve said there as it doesnt make sense to me and I need to understand properly.

Are you saying one cotton wool ball as opposed to two pinches makes a material difference to the effective mass of a 4.5gm tonearm? I can't see that it does but I can easily believe that my arm is more effectively damped.

And can you explain what movement takes place inside the tonearm that Ive unwittingly restricted? The only (desirable) movement is surely where the wire exits the tonearm and enters the mounting plate.

And finally, your comment about the bearing having a 5 micron clearance is completely baffling. Isnt that the tolerance to which the bearing is machined? I dont understand how you can tighten a bearing to a tolerance of 5 microns.

I apologise if my questions come across as aggressive, they certainly arent meant to be. I have made no attempt to appear knowledgable when recounting my experience and youre effectively saying Ive done it all wrong but without any facts to support your statements. I need to understand how Ive spoilt my beloved turntable and if you can explain that properly, I'll happily undo everything and be grateful to you for the advice.

Kind regards

Dezie



Dezie

[cafe latte]

Thanks Cafe. I dont have any knowledge or experience in such things but Im going to challenge what youve said there as it doesnt make sense to me and I need to understand properly.

Are you saying one cotton wool ball as opposed to two pinches makes a material difference to the effective mass of a 4.5gm tonearm? I can't see that it does but I can easily believe that my arm is more effectively damped.

And can you explain what movement takes place inside the tonearm that Ive unwittingly restricted? The only (desirable) movement is surely where the wire exits the tonearm and enters the mounting plate.

And finally, your comment about the bearing having a 5 micron clearance is completely baffling. Isnt that the tolerance to which the bearing is machined? I dont understand how you can tighten a bearing to a tolerance of 5 microns.

I apologise if my questions come across as aggressive, they certainly arent meant to be. I have made no attempt to appear knowledgable when recounting my experience and youre effectively saying Ive done it all wrong but without any facts to support your statements. I need to understand how Ive spoilt my beloved turntable and if you can explain that properly, I'll happily undo everything and be grateful to you for the advice.

Kind regards

Dezie



Dezie

Ok first the tonearm wire needs to move as the arm moves and packing it will hinder this, seconds a pinch is all that is needed to prevent the arm ringing and you will be amazed the compliance diference you can make packing the arm solid. Also I said the bearing clearances were 0.5 a micron which is about the size of a bacteria so you are not going to be able to guess this messing with a screw driver, So nobdy should ever touch these screws as you are just going to ruin the arm.
Regards
CL

[Dezie]

Thanks for resonding Cafe. I'm afraid we're going to have to agree to differ.

You say the wire in the tonearm moves. But if you look at how tight the original wires are in the space between the arm and mounting plate, I think you could only conclude that no movement was intended. My re-wire is neither more nor less tight or restricted than the original.

And yes, Id be surprised at the compliance difference a ball of cotton wool makes...but you dont say what it is. Compliance is all about mass and I can assure you a ball of cotton wool doesnt materially affect the mass of a 4.5gm tonearm. But the effect of a packed tonearm is incredible...complete silence. I dont know what a pinch at each end does, maybe the same, but if the arm remains hollow in between, Id suggest there's still potential for unwanted noise.

And your last comment doesnt answer my question. Maybe theres a misunderstanding. 5 microns refers to the tolerance to which the bearing was manufactured ie, it is almost perfectly uniform around the entire circumference, not to the bearing clearance. Come to think of it, would a bearing with a clearance of 5 microns move at all? Maybe an engineer could answer that. You can over or untertighten your bearing, and the difference will be felt in stiffness or excess play, but it's really not difficult to get it just right.

Ultimately I like what Ive done to my deck and it sounds amazing, as confirmed by my test record. If you like what youve done to yours, be happy!

Maybe we should just agree to enjoy our modified decks in our own way and let others decide how best to modify theirs. My original post was intended to encourage those who, like me, have no prior experience to have a go. And I hope our debate better informs people who are considering it.

Kind regards

Des

[cafe latte]

Thanks for resonding Cafe. I'm afraid we're going to have to agree to differ.

You say the wire in the tonearm moves. But if you look at how tight the original wires are in the space between the arm and mounting plate, I think you could only conclude that no movement was intended. My re-wire is neither more nor less tight or restricted than the original.

And yes, Id be surprised at the compliance difference a ball of cotton wool makes...but you dont say what it is. Compliance is all about mass and I can assure you a ball of cotton wool doesnt materially affect the mass of a 4.5gm tonearm. But the effect of a packed tonearm is incredible...complete silence. I dont know what a pinch at each end does, maybe the same, but if the arm remains hollow in between, Id suggest there's still potential for unwanted noise.

And your last comment doesnt answer my question. Maybe theres a misunderstanding. 5 microns refers to the tolerance to which the bearing was manufactured ie, it is almost perfectly uniform around the entire circumference, not to the bearing clearance. Come to think of it, would a bearing with a clearance of 5 microns move at all? Maybe an engineer could answer that. You can over or untertighten your bearing, and the difference will be felt in stiffness or excess play, but it's really not difficult to get it just right.

Ultimately I like what Ive done to my deck and it sounds amazing, as confirmed by my test record. If you like what youve done to yours, be happy!

Maybe we should just agree to enjoy our modified decks in our own way and let others decide how best to modify theirs. My original post was intended to encourage those who, like me, have no prior experience to have a go. And I hope our debate better informs people who are considering it.

Kind regards

Des

Not 5 micron, but 0.5 micron and I asure you it is the bearing clearance which is why is is not recomended to mess with those screws any why I always recommend when these bearing have any issues just change the arm. The arm wires do actually move a little as the arm gets closer to the spindle they are pulled were the wire goes into the base of the arm, you can even see them pulling. When the arm moves to the rest they slightly bunch up. If you restrict this slight bunching and pulling it MAY cause issues, but if your arm is still able to hover when balanced at the spindle end (worth a check) you might be alright, but if the arm moves back to the rest when balanced the wires are too tight. I would not want to increase the effective mass at all and cotton wool weighs more than you think and depending on its distribution will have more effect than you think, but if your cart is of lower compliance it is not a worry (my main cart is very high compliance). My main worry as i said is the bearing as you could quite honestly have it tightened factors of 10 out and you could not tell. If you are happy it is the main thing, but undooing bearings is not something I would encourage anyone to do when to rewire an arm it is not necessary.
Regards
CL