Question About SL-1600 MK2 Cuing

[boreas]

Hi, all. I have a 1600 MK2 which is essentially perfect in every respect except one. There's an odd situation with the operation of the cuing.

As you may know, these tables have two means of raising and lowering the cuing bar. There's the usual lever at the base of the tonearm but there's also a button next to the power switch. The strange thing is that both these controls actuate the same accessory motor to raise or lower the platform. In other words, there are two controls which seem to do the same thing in the same way. As an indication of this, when you push the button, the cuing platform moves and the lever does too.

Now, here's my conundrum. If I use the button, the cuing works perfectly. Push once and the platform comes up. Push again and the platform goes down. But if I use the lever, raising it causes the platform to rise but lowering it does nothing. Or it did nothing until I operated it a number of times while pushing on the platform. Now the platform will go down about 1/3 of the way. Nevertheless, I can hear the motor working so,

So, I'm wondering whether a shot of silicone oil will free the piston up a bit. But that raises the question of why the piston moves down freely when the button is pushed but not when the lever is used. There's also the question of whether Technics even used silicone damping on this model. The MK2 1600, 1700 and 1800 aren't mentioned in the service bulletin covering replenishing the silicone fluid and, in looking at the service manual, I don't see where silicone would be necessary.

Thanks! Any advice will be greatly appreciated.

John

 

[forgetcolor]

I don't think the problem is lubricant, but a sticky switch. I haven't looked closely at the switch that cue lever actuates, but there must be one and my guess is it's sticking in the up position.

Get some Deoxit and try spritzing down where the cue lever attaches to the tonearm assembly. Or, if more adventurous, remove the top part of the case so you can see more of what you're doing (pretty easy). Either way, before you turn it on, but after you spray some Deoxit, manipulate the cue lever several times and see if you can hear the switch go on/off with up/down. If not, spray again, exercise lever again, repeat.

 

[boreas]

I don't think the problem is lubricant, but a sticky switch. I haven't looked closely at the switch that cue lever actuates, but there must be one and my guess is it's sticking in the up position.

Get some Deoxit and try spritzing down where the cue lever attaches to the tonearm assembly. Or, if more adventurous, remove the top part of the case so you can see more of what you're doing (pretty easy). Either way, before you turn it on, but after you spray some Deoxit, manipulate the cue lever several times and see if you can hear the switch go on/off with up/down. If not, spray again, exercise lever again, repeat.

I don't think it's lubricant either but I'm having a hard time seeing it as the switch. The job of the switch is to start the motor and it does. The motor is working. I can hear it with the table fully assembled and both hear it and see it with the platter and cover removed. The motor operates at the same speed and for the same duration, whether forward or reverse, regardless of which of the two controls is operated.

All that the motor does is rotate the cam and both controls rotate it equally. The problem is that the spring doesn't push the platform all the way down when the lever is used (unless I push on the platform) but it does, without my assistance, when the button is used. Also, I can see and hear the motor continuing to spin the cam after the platform stops about halfway to full descent.

 

[boreas]

Something strange has occurred. I posted an image of the cuing automation in the OP and I can see it in my post on the computer I used to post it but not on another computer. Also, when I look for the image in my AK attachments, on either computer, its' not there. Weird!

Anyway, I'm going to try again.

John

 

[Montycat]

John, it's been a while since I had a 1600 open in front of me but I might later this week as I just traded a Dual 1019 for one that, oddly enough, has some auto start/cueing issues. The pics in the SM are quite bad so I'd like to get in and have a look anyway.

 

[Montycat]

Something strange has occurred. I posted an image of the cuing automation in the OP and I can see it in my post on the computer I used to post it but not on another computer. Also, when I look for the image in my AK attachments, on either computer, its' not there. Weird!

Anyway, I'm going to try again.

John

Ohhh, that's a not bad pic. The main thing is how does the lever interface with the rotating cam? Maybe the cam is not moving so the arm platform can't descend into the lower part of the tray.

 

[boreas]

Ohhh, that's a not bad pic. The main thing is how does the lever interface with the rotating cam? Maybe the cam is not moving so the arm platform can't descend into the lower part of the tray.

Hi, Andrew!

I think the cam has to be moving because a: the motor and pulley can be seen to move and b: the cuing platform can be pushed down fully so I'd have to assume that the cam has been rotated to the correct position. This is a puzzler! I'll be grateful for any insight you can offer once you've dug into the one you're getting.

John

 

[boreas]

Problem seems to be more or less solved but the mystery remains.

Well, by working the lever (which is really a toggle switch) up and down, up and down repeatedly, I've managed to bring the cuing bar down all the way but with about a 2 second hiccup for the last millimeter. To be on the safe side, I adjusted the cuing bar down a bit so that the arm is unhindered before that last little drop.

So, mechanically, things work fine with either the button or the lever. I don't know what effect my adjustment will have, if any, on the muting switch. As I recall, the adjustment for that was fairly sensitive. I'll have to put the 1600 back in the system to check.

Meanwhile, I STILL don't know for sure why there should be such a difference between the results with the two controls. With the platter and cover removed, I can see the motor, the pulley and the cam. All three move just as fast and just as much, no matter which control is used. (Both controls operate the same switch.) The difference is in how the cuing bar reacts.

By the way, I did try some silicone down the screw hole as per "Method A" in the Technics service bulletin on adding silicone. All it did was fill up the screw hole so that I couldn't get the screw back in all the way. I don't think any of the other methods are applicable either.

John

 

[jasonsong86]

I believe the way it works is the lever is connected to some switches that send signal to the motor to turn the cam.
When you lower the lever, the switch disengage and the cam turns and the arm lowers.
Now the difference is when using the button it override the switches, so if one of the lever switches are not working it will not function correctly.

 

[boreas]

I believe the way it works is the lever lifts the arm and there is a switch that sends signal to the motor to turn the cam in position to hold the arm in place.
When you lower the lever, the switch disengage and the cam turns and the arm lowers.
Now the difference is when using the button, the gear is turning a full cycle instead of turning back when using the arm and the switches over the years is work so the cam can not position itself properly.

No, the lever is just a toggle. It doesn't actually lift anything. It just throws the switch and the switch turns the motor on. When you raise the lever, it makes the motor (and the pulley and the gear and the cam) spin in one direction and when you lower the lever it makes the motor spin in the other direction.

The cam doesn't rotate in a full circle. It rotates one way to raise the arm and the other way to lower it. There are "limiting switches", LS1 and LS2 in the diagram, which stop the motor when the cam is in the fully raised position (LS1) and when it's in the fully lowered position (LS2).

John

 

[boreas]

I should add that moving the lever initially, either up or down, does nothing until it reaches about the half-way point in its travel. Then there's an audible click and the motor starts. The cuing bar then begins to move and the lever moves the rest of the way on its own.

John

 

[jasonsong86]

No, the lever is just a toggle. It doesn't actually lift anything. It just throws the switch and the switch turns the motor on. When you raise the lever, it makes the motor (and the pulley and the gear and the cam) spin in one direction and when you lower the lever it makes the motor spin in the other direction.

The cam doesn't rotate in a full circle. It rotates one way to raise the arm and the other way to lower it. There are "limiting switches", LS1 and LS2 in the diagram, which stop the motor when the cam is in the fully raised position (LS1) and when it's in the fully lowered position (LS2).

John

You reply too fast, I already changed my initial thoughts.
I suspect there are two switches one for up and one for down. One of them is broken or out of spec.

 

[boreas]

You reply too fast, I already changed my initial thoughts.
I suspect there are two switches one for up and one for down. One of them is broken or out of spec.

There are two switches but not one for up and one for down. Both switches will do either. There's a switch operated by the button (S403) and another operated by the lever (S409). The thing that makes me think both are working correctly is that the motor and the parts driven by the motor respond in exactly the same way to either switch.

John

 

[jasonsong86]

There are two switches but not one for up and one for down. Both switches will do either. There's a switch operated by the button (S403) and another operated by the lever (S409). The thing that makes me think both are working correctly is that the motor and the parts driven by the motor respond in exactly the same way to either switch.

John

That is very weird that it would behave differently.
Maybe some screws are loose and causing the metal pieces moving not lined up when using the lever?
Now does the lever move up and down with the button?

 

[boreas]

After adjusting the cuing height so that the bar always out of the way at "touchdown", the muting switch closes at just about the correct time. With the button, it's pretty much spot on. With the lever, there's usually a slight delay which varies slightly but is never more than a second.

I'm calling it fixed.

Thanks for all the suggestions!

John

 

[Frank Sol]

Good news... :thmbsp:

 

[boreas]

Good news... :thmbsp:

Yeah, it is! Thanks!