Different SX-850 Dial Scales?

[mstewart]

Hello, a while ago I purchased a SX-850 that had a scratched up dial scale. Luckily I was able to find a replacement in great condition. One of the things I noticed when Installing the replacement dial scale is the bottom area where the dial pointer sits is shorter. So instead of the whole bottom of the dial pointer being supported it is teetering on the edge. As a result dial pointer wants to fall forward. Has anyone seen this? Do I need a different dial pointer to match the dial scale? Did I end up with the wrong dial scale?I can provide photos if it would help. Thank you

 

[mstewart]

Trying to explain better. If I tune to the right the dial pointer leans forward. Then if I tune to the left the dial pointer will tilt back somewhat instead of the dial pointer staying in the same position regardless of whichever station I'm tuned to. Do anyone know what would be causing this?

 

[SimplerTimes]

Pictures? Old vs new?

 

[mstewart]

Pictures? Old vs new?

View attachment 1883830 View attachment 1883830

It's somewhat difficult to show but the old one that has been removed is longer on the bottom right where the pointer sits. I measured the depth with a scale and found it to be about 7/16 on the original one vs about 1/4 deep on the replacement. I am not positive but it seems like there is nothing supporting the pointer so it's not in the proper position. However, if I turn the tuner all the way to the right it pulls in like it should. Then if I move the pointer to the left it slips down a bit. i tried to illustrate this in the photos. The thing that I don't understand is that the dial scale that I recently installed looks identical to the one I took off. Except for how far the bottom sticks out. There are no obstructions that the pointer is hitting. The string is not rubbing anywhere.

 

[SimplerTimes]

Pictures?

Your new one does look shorter than the old one. However, I checked my SX-950, 1050 and both of my 1250’s and they all look to be about 1/4” thick at the ledge you are referring to. I was going to suggest that maybe you have a dial scale from one of those models except that the 850 scale assembly would only have speaker A and speaker B lights which yours do have. I can only conclude that the old scale you have is the anomaly.

 

[zebulon1]

I think there’s a brushed aluminum trim piece that is screwed in front of the pointer. It extends the length of the face. Maybe you left it it off for clarification?

 

[mstewart]

I think there’s a brushed aluminum trim piece that is screwed in front of the pointer. It extends the length of the face. Maybe you left it it off for clarification?

Yes, I have the blind sash. It's just not installed. It does not help to support the dial pointer when it's attached though.

 

[mstewart]

Your new one does look shorter than the old one. However, I checked my SX-950, 1050 and both of my 1250’s and they all look to be about 1/4” thick at the ledge you are referring to. I was going to suggest that maybe you have a dial scale from one of those models except that the 850 scale assembly would only have speaker A and speaker B lights which yours do have. I can only conclude that the old scale you have is the anomaly.

That's what I was thinking. I know the 950's and up have lights for A,B,C. So it seems to me that the scale has to be for an 850. I tried looking at different service manuals and they all showed the same part number for the dial scale too. So I'm wondering what is up with this thing!? I bought a replacement pointer online a while ago just to see if it would be any different. The worst case scenario is that it just stays how it stays. I was just about to get into a full restoration on this. I hate doing half assed repairs.

 

[Watthour]

My WAG would be torsion on the nylon dial cord. The cord is sprially wound, after all. If the cord is waxed it may allow the cord to slip past the guide pullleys without imparting that torsion. I vaguely recall fighting this on a unit in the past, but didn't make specific notes regarding it.

 

[mstewart]

My WAG would be torsion on the nylon dial cord. The cord is sprially wound, after all. If the cord is waxed it may allow the cord to slip past the guide pullleys without imparting that torsion. I vaguely recall fighting this on a unit in the past, but didn't make specific notes regarding it.

That makes sense. I have observed that while adjusting the tuner in either direction one or more of the pulleys may not turn. The shaft the tuner knob is connected to appears to be somewhat bent. It was like that before removing the dial scale. It seems there is indeed uneven tension on the string.

On a side note, while I do have a manual which shows how the dial string is to be routed I am not positive I have it correct. I found it difficult to tell from the diagram exactly how it is supposed to be. I am attaching photos with the hope someone can verify if it looks right.

 

[Watthour]

There should be tension (pull) on the dial cord. Things could go very badly if there were no tension. The problem is that there may also be torsion (twisting force) imparted by the string if it is not moving freely.

 

[mstewart]

There should be tension (pull) on the dial cord. Things could go very badly if there were no tension. The problem is that there may also be torsion (twisting force) imparted by the string if it is not moving freely.

Do you have any idea how I might get it working correctly? There is tension in the sense that the string is tight enough to move the pulleys on the right side. How tight it needs to be, however, is not clear to me. I wonder if trying to lubricate the inner diameter of the left 2 pulleys would allow them to move better. I haven't done that. I also have violin rosin here if I need to try to get the string to grab better. Also, I am wondering if I should replace the shaft connected to the tuner knob due to it turning out of round, which just looks like it's bent to me.

 

[zebulon1]

The Pulley on the VC - tuning capacitor has a spring that holds the tension on the string.

 

[mstewart]

The Pulley on the VC - tuning capacitor has a spring that holds the tension on the string.

Yes there is tension on the spring.

 

[mstewart]

Heres an update. I received a replacement dial pointer. Figured what the heck it's worth a try. Observed something interesting about the replacement. The plastic portion was shaped slightly different and the round posts that the string wrap around were all round. On the one I took off the 2 plastic outer posts were larger and oval. Also it had a crack in it! The new pointer is behaving normally now. I wonder if the pointer that was on it originally was made for the dial scale that I removed? Don't know why it was broken. I think someone had their mitts on it at some point in history.