My new Technics SL-1310MkII and the famous cueing problem

[Blue Meanie]

i own a 1310mk2 i did that pic of the broken part .thried to glue it no chance:thumbsdn:
so i use my tt manual it is good to take the broken part out because it has effect on the friction of the arm when broken

Sorry I posted your pic without proper recognition of the source. I had found it years ago, and couldn't recall where I had gotten it from. My bad.:thumbsdn:

 

[SaSi]

So, here we start with the disassembly. I start where the disassembly instructions I posted yesterday end.

There are three Philips screws holding the tonearm assembly to the sub chasis. When the screws are undone, the tonearm is simply lifted from the chasis.

 

[SaSi]

The closeup before further disassembly shows the broken offending part. In hindsight - after total stripdown - I see it is broken not where my original diagram showed but on the opposite part of the ring shaped part.

The first thing that needs to be removed is the tonearm termination PCB. It is secured by a 2 screw holder at one end and one screw through the ground wire at the other end.

 

[SaSi]

Next step is to undo the screw holding the spring shaped tonearm cable guide.

Then the tonearm fixing plate (TA-25) needs to be unfastened by means of the two screws securing it to the main tonearm assembly.

 

[SaSi]

In the next few pictures we see the tonearm fixing plate unfastened and shifted out of place. A bit of care needs to be excercised so as not to harm the tonearm cables. They are not as fragile as they may seem.

 

[SaSi]

The next few pics show the riser assembly mounted in place. It comprises of two plastic parts mounted through a rod - the riser rod - which in turn is spring loaded to facilitate the lowering of the tonearm.

In other words, the plastic part that breaks is pushed by the other part that takes motion from the lever or a pin beneath that - from the automatic start/stop mechanism. They push the rod upwards to raise the tonearm. When their pressure is removed, the spring returns the tonearm down.

Damping is achieved by a snug fit of the metal rod through the shaft on the tonearm assembly and the help of some thick oil. Apart from fixing the plastic broken part, that oil seems to have dried out a bit - practically turned into goo.

Right now, however difficult it might prove to fix the plastic lever, the real challenge will be to put everything back together in a way that they work. But comparing the assembly with the tonearm blow out diagram helps and makes things seem much simpler now.

 

[SaSi]

Next step is to remove the plastic levers from the riser rod. There is a C clip, a washer and a spring, then there is the broken part, another washer - which incidentally I found laying inside the tonearm base cavity - and then the top plastic part.

The next few pictures depict the broken part from various angles as it was removed from the "pit".

In the last two pictures I tried to depict a side that has grown worn by some sort of friction. My guess is that it happened as the plastic lever broke and the arm lift lever and assosiated metal plate shaved pieces of the plastic that could not move as designed.

I have no idea if this wear will have any mechanical effect on the operation of the piece if I am able to glue it back together and try to make it work in place.

 

[SaSi]

And in the next few pics I show the same assembly part after cleaning it with water and dish soap using a smooth brush. During cleaning, that small half broken piece of the ring was almost trying to go away...

What appears to be oil in these pics is actually water left over from cleaning. I didn't take any further chance with it in fear of further disintegration.

My aim is to glue the piece together, at least for the purpose of having a whole piece as reference to what is needed - perhaps custom built.

 

[SaSi]

And the final pictures for now: The cleaned part clamped with glue.

I affixed two drops of cyanoacrylate glue and pressed the two edges of the broken ring together. A few minutes later I clamped it with the mini clamp as seen in the picture.

I subsequently dropped a few more drops of glue over the half-set one and used cotton buds to wipe any leaking glue.

The glue holds the pieces together, however I doubt it will be able to withstand the pressure from the raise lever. Please have a look at the second picture on post #26 to see how the raise lever applies pressure there through a metal plate.

And now I am open for suggestions. I won't do anything more tonight - it's now past midnight.

 

[Stanton681EEES]

You could be right. I am guessing that aluminium would be strong enough. But there are a few other plastic parts in touch with this one that might fail in case this one can take the punishment. Moreover, the piece *might* need to be elastic in order to work properly. Would Teflon be a good material?

I don't know if this is the case until I disassemble the toneram. More about that in a few hours.

Maybe something like Carbon Fiber.

 

[Stanton681EEES]

So, here we start with the disassembly. I start where the disassembly instructions I posted yesterday end.

There are three Philips screws holding the tonearm assembly to the sub chasis. When the screws are undone, the tonearm is simply lifted from the chasis.

From the look of these pictures, if the 1500MKII is like this, i bet a 1800MKII arm would drop rite in, an fit nicely. The base looks so much like an 1800MKII as well as the 1600 and 1700MKII but those wouldn't work do to being automated arms. and you'd need the little board that controls the auto functions. But i bet an 1800MKII arm would work. Problem is finding an 1800MKII that isn't working. Trust me those are few and far between.

 

[Ty_Bower]

Very good work. I really appreciate the time you invested to take such detailed photographs.

Here's a quote from near the bottom of the blog linked earlier in this thread:

The plastic part refered to is way too thin where a metal shaft runs trough it. It can be repaired with glue and special thin fishing line wrapped around for reinforcement. Without the line it’s likey to break again sooner or later.

 

[Blue Meanie]

Would Teflon be a good material?

I've never seen Teflon as a "chunk" of anything. Only as a coating and tape.

 

[SaSi]

I've seen washers and spacers supposedly made out of teflon. It looks ... just like the material the broken part is made of.

I have studied the mechanism for lifting the arm. I need to understand how it should work or should have worked as the broken piece may have caused misalignment of levers inside the assembly.

My guess is that the failure is caused by the damping oil turning into goo and causing too much friction.

For this one, I've taken the road of glueing the riser assembly on the bearing it rotates, using that as a steel support for holding the plastic piece together.

But I need to clean everything from what is left of the damping fluid, ensure the riser assembly moves freely up and down and then apply damping.

For my first attempts - operate the tonearms cue lever, I don't need any damping so the process is focused in cleaning, testing and a clean assembly.

 

[Blue Meanie]

I've seen washers and spacers supposedly made out of teflon. It looks ... just like the material the broken part is made of.

Interesting. I'm assuming the original part (just a guess) is made out of delrin.

Your effort so far regarding this is quite impressive!:thmbsp:

 

[junkaudio]

these are realy great tt if anybody got a solution to the broken part i would be even more happy with my sl-1310 mk 2 .joel of the tt factory new how to fix it

 

[SaSi]

The tonearm assembly is now reassembled and functional. However with several side issues:
The riser rod seems to have issues travelling vertically. Too much friction. I've cleaned the rod but not the shaft. The spring that loads the rod for lowering isn't strong enough.

The cue lever raises the rod but not smoothly. Again due to friction.

It seems that there is no other alternative than a total stripdown for thorough cleaning. I wanted to avoid unsoldering the tonearm wires but it seems there is no avoiding it.

 

[SaSi]

LESSON LEARNT: When you are careless you make mistakes and pay the price.

When I applied the drops of glue, I didn't realize that the rotating steel bearing was secured with a C clip of sorts. The result was that lots of glue contaminated the rotating surface making rotation difficult.

Attached is a picture of the bearing with glue. Please don't bash me. Be kind. I'm still learning...:tears:

But all is not lost. Lots of careful cleaning accompanied with closeups of the surface has already shown marked improvement. More to follow later.

It is important to point out that the broken piece problem is apparently fixed and I am now working towards solving new issues I created myself.

 

[goat67]

Is it possible to wrap something around the area that broke to keep it secure and re-enforce it fishing line or a small tie wrap? I am only asking because it may break again.

 

[SaSi]

Is it possible to wrap something around the area that broke to keep it secure and re-enforce it fishing line or a small tie wrap? I am only asking because it may break again.

What you say is right. But the first problem is to find out what caused the break in the first place. After several clean/assemble/try/investigate attempts, I think I now understand the reason for failure. It is not the plastic part by itself. On the unit I'm working on I've found two reasons for the failure.

I've decided to permanently attach the plastic part to the metal pulley it is normally attached by friction. I made the mistake to glue it in place - I should have removed the pulley and glue them out of the rod, but after some tedious cleaning it is now back to normal.

I am going to present the assembly process with detailed pics and annotations to show where the problem is.