Dual CS1257 swiching speed between 33⅓ and 45 RPM.

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apastuszak
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Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by apastuszak » 27 Oct 2019 14:52

Hello all.

I've been trying to do as much as I can on my own before i went to the experts for help. But I am dumbfounded, so I thought I should ask for help.

I bought a Dual CS1257 at a Goodwill store in the US for around US$13.00. I hooked up it, and all seemed to go well. After a few weeks of using it, I noticed two distinct problems:

1. The turntable would occasionally play backwards.
2. If I left it on for a while, there would be a pretty annoying hum from the turntable.

Then a few weeks after that, the turntable would only play at 33⅓ RPM. Switching to 45 RPM did nothing.

I managed to find a Technics SL-D2 for $40 on a local listing from Offerup.com and put away the Dual. There's a whole story behind the Technics, which I'll get into in another post, but it became a main turntable. The Dual just kind of sat in the corner in my basement unplugged.

2 weeks ago, i decided to bring the turntable back from the dead. Some Google searches led me to a vinylegine post about fixing the reverse spinning platter (which I jokingly call the 'Catholic School Special' because the nuns at my grade school used to play Beatles records backwards to show us the evil messages in their music). It told me that I needed to recap the power supply and even included Mouser part numbers. I'm no expert at soldering, but I had done it before. So I decided to tackle the project.

Here's a nice "in progress" shot whith one cap already replaced.

https://i.imgur.com/UY5E6AL.jpg

The caps were in BAD shape

https://i.imgur.com/mwrObpl.jpg

https://i.imgur.com/Q38daZz.jpg

Once that was done, both the backwards spinning and the buzzing was gone. I felt victorious.

The next issue to tackle was the auto-return not working. This lead me to the steuerpimpel being the issue. Ordered a new one from mrow22 and am waiting on it. In the meantime, I hacked it using the insulation from a piece of 12 gauge solid core wire. Now the auto-return works. i did lose an e-clip in the process, but I actually found 2 at Home Depot. For now, some blue tac is holding it together till the steuerpimpels get here. I HATE e-clips. I was temped to buy a small bolt, washers and a nut to replace the shaft with the 2 e-clips.

With that probkem fixed, and feeling rather good about myself, I decided to tackle the speed issue. I took off the platter and watched what was going on. When I flick the lever to 45 RPM. the mechanism slides the belt down, but it doesn't slide all the way down on the pulley. It only gets halfway down and continues to spin at 33⅓ RPM.

My initial thought was that the belt was loose and orignial to the turntabale, so I ordered a new belt from eBay. And, low and behold, the thing went smoothly to 45 RPM. BUT, it would not go back to 33⅓ RPM! When I flicked the lever to 33, the belt goes halfway up the pulley and gets stuck. So, the new belt gives me the exact opposite problem.

Here is a video I made of the problem:



I returned the belt to the seller, and found another one on turntableneedles.com, that they claim is the right belt. It's an FBM13.3, which is shorter than the stardard FBM13.3 just for Duals. This belt has the same issue, but it also won't let me lock the speed in. It keeps drifing from too slow to too fast no matter what I set the pitch control at.

So, I went Googling and a number of other sellers have belts for the Duals. One website has an FBM13.1 listed as the right model for this turntable. The comments for the belt I bought on turntableneedles.com says that the right belt to use is an FBM13.5, which I can only find on one website and when you factor in shipping and handling is a tad expensive.

The other thing I noiced is that the belt in the Dual has a "rough side" and a "smooth side." The 1257 service manual says the "smooth side" needs to face in, which makes sense. You want the smooth side to help slide the belt up and down the pulley.

None of my replacement belts have a "smooth side."

So, my questions now are:

1. Is this even a belt issue?
2. What is the right belt for this turntable?

If I could order a 13.1, 13.3, 13.5 and 13.6 and experiment, I would do so, but I can't find one site that has them all at a reasonable price.

Any help with this issue reall appreciated.

lbls1
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Re: Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by lbls1 » 27 Oct 2019 18:19

I have heard of a lot of the Duals of that vintage having that problem. I had a similar problem, but my craft did not have the reverse play (probably a different motor).
What I did was actually nothing other than switching it from 33 to 45 and back but more often. Somehow the problem corrected itself. I believe that many turntables in this genre played primarily 33 rpm records, and the non use of 45's may have added to the problem of switching gears.

You could look into replacing the spring on the arm of the belt guide, to see if that will help. Good luck.

apastuszak
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Re: Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by apastuszak » 27 Oct 2019 18:32

That's a good idea. Let me see if I can locate one of those somewhere.

Thank you.

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Re: Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by mrow2 » 27 Oct 2019 18:42

Hi The thing to know about these belts is that it may possibly have as much to do with the smiling gods as with technical specs. Rough side vs smooth: AFAIK there are not any "ground" belts available now (this was the description for Dual originals, besides precise dimensions). Sure, and leave it to Dual to come up with a belt spec which isn't available in the modern era. My experience (I wrote about this in the PDF which you may have, now -- maybe I should put it in bold fonts) is that with Duals, a proper belt has to do with precise thickness, length and width. Mostly, 1257s work fine but I don't know exactly which of those examples will work in your case. I found that tighter belts were less likely to shift speeds in one direction so I'd tend to opt for the slightly looser ones, like the FMB 13.5 and 13.6, but it's just a guess. You want to be sure the mechanism is tip top, clean in every respect, with the pulley and cone clean and in perfect condition. In the absence of complete success I might opt for the one which comes closest and (fingers crossed) wait for it to settle in. I like the idea of working the mechanism, as well. Keep us posted, please. Maybe someone else has a more specific answer. I suspect you can achieve success without messing with the springs.

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Re: Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by apastuszak » 27 Oct 2019 19:10

lbls1 wrote:
27 Oct 2019 18:19
I have heard of a lot of the Duals of that vintage having that problem. I had a similar problem, but my craft did not have the reverse play (probably a different motor).
What I did was actually nothing other than switching it from 33 to 45 and back but more often. Somehow the problem corrected itself. I believe that many turntables in this genre played primarily 33 rpm records, and the non use of 45's may have added to the problem of switching gears.

You could look into replacing the spring on the arm of the belt guide, to see if that will help. Good luck.
I just double checked and it look like the belt guide doesn't use springs to go between 33 and 45. I'll have to flip it over again and see what's going on inside the thing.

apastuszak
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Re: Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by apastuszak » 27 Oct 2019 19:28

mrow2 wrote:
27 Oct 2019 18:42
Hi The thing to know about these belts is that it may possibly have as much to do with the smiling gods as with technical specs. Rough side vs smooth: AFAIK there are not any "ground" belts available now (this was the description for Dual originals, besides precise dimensions). Sure, and leave it to Dual to come up with a belt spec which isn't available in the modern era. My experience (I wrote about this in the PDF which you may have, now -- maybe I should put it in bold fonts) is that with Duals, a proper belt has to do with precise thickness, length and width. Mostly, 1257s work fine but I don't know exactly which of those examples will work in your case. I found that tighter belts were less likely to shift speeds in one direction so I'd tend to opt for the slightly looser ones, like the FMB 13.5 and 13.6, but it's just a guess. You want to be sure the mechanism is tip top, clean in every respect, with the pulley and cone clean and in perfect condition. In the absence of complete success I might opt for the one which comes closest and (fingers crossed) wait for it to settle in. I like the idea of working the mechanism, as well. Keep us posted, please. Maybe someone else has a more specific answer. I suspect you can achieve success without messing with the springs.
I'm going to try a 13.6 belt, since that one can be obtained for a reasonable price. You emailed me your PDF on Friday night and I read through what I could on my iPad. I'm going on a busines trip to Maine, so I won't get to play with it again until probably Friday.

The belt I ordered off of eBay that I returned was a T13.3. I didn't check that one for speed accuracy.

I'm tempted to track down a NOS belt, but I'm sure they're a fotune AND they will be 30+ years old. Who knows what condition the rubber is in.

The big thing is going to be speed accuracy. With the FBM13.3, I can't get the speed to be locked on. With the existing belt, I can get the line on the platter to not move. With the new belt, it moves back and forth between too slow and too fast.

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Re: Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by apastuszak » 27 Oct 2019 20:37

Just ordered a 13.5 and a 13.6 belt off of eBay. We shall experiment next week when they get here. In the mean time, i will just put the original belt back in and just listen to 33⅓ RPM albums for now. The FBM13.3, i will return, since it doesn't even keep a constant speed.

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Re: Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by musicmn » 27 Oct 2019 21:54

Hi, I've worked on a lot of belt drive dual turntables and have also tried a lot of belts along the way. The only belt I will use and recommend for any dual belt drive turntable are the ones sold by William Thakker out of Germany. His belts are made to Dual's exact measurements and work. They not only get the platter to the correct speed but are the only belts I have tried that work on duals sensitive shift mechanism. Like Don said make sure that the speed shift mechanism is super clean and use very little grease on the moving parts. Thakker belts may cost a little more and you will have to wait longer for it to arrive from Germany. But it's well worth that for a high quality belt that will out last any sold on ebay. I just checked Thakker's web site and he does have a platter drive belt for the 1257 If I knew how to provide a link I would have. On another subject make sure that the new capacitors that you are using to replace the old Rifa brand have and X2 rating like the old Rifa's. This is a must because the power going to the motor and the board for the motor is AC not DC. The Capacitors I have been using in place of the Rifa's are from Mouser supply and are made by Panasonic. Here is Mouser's parts numbers for them the 0.01 uf x 250 volt is 667 ECQU2A103KL, for the .068 uf x 250v is 667 ECQU2A683KL, and for the 0.33uf x 250v 667 ECQU2A334KL. These are all X2 rated safety caps with nice long leads that work well on this board. I hope this helps.

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Re: Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by apastuszak » 28 Oct 2019 00:41

musicmn wrote:
27 Oct 2019 21:54
Hi, I've worked on a lot of belt drive dual turntables and have also tried a lot of belts along the way. The only belt I will use and recommend for any dual belt drive turntable are the ones sold by William Thakker out of Germany. His belts are made to Dual's exact measurements and work. They not only get the platter to the correct speed but are the only belts I have tried that work on duals sensitive shift mechanism. Like Don said make sure that the speed shift mechanism is super clean and use very little grease on the moving parts. Thakker belts may cost a little more and you will have to wait longer for it to arrive from Germany. But it's well worth that for a high quality belt that will out last any sold on ebay. I just checked Thakker's web site and he does have a platter drive belt for the 1257 If I knew how to provide a link I would have. On another subject make sure that the new capacitors that you are using to replace the old Rifa brand have and X2 rating like the old Rifa's. This is a must because the power going to the motor and the board for the motor is AC not DC. The Capacitors I have been using in place of the Rifa's are from Mouser supply and are made by Panasonic. Here is Mouser's parts numbers for them the 0.01 uf x 250 volt is 667 ECQU2A103KL, for the .068 uf x 250v is 667 ECQU2A683KL, and for the 0.33uf x 250v 667 ECQU2A334KL. These are all X2 rated safety caps with nice long leads that work well on this board. I hope this helps.
The capacitors are indeed X2. I believe I got the Mouser part numbers from one of your previous posts. My only hesitation was that one of the original capacitors was Y rated and not X, and I wasn't sure if putting an X2 in it's place was a good idea.

Thanks for the tip on the Thakker belt. I'll go check out the website and place an order.

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Re: Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by apastuszak » 28 Oct 2019 00:49

Thakker has an eBay store! That made it very simple. I paid €18.56 for the belt and that included shipping to the US. Says it won't get here from a month. But I'm still able to play 33s with the existing belt, so I am OK.

https://www.ebay.com/itm/391176293649

Thank you for the tip!

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Re: Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by lbls1 » 28 Oct 2019 03:31

apastuszak wrote:
27 Oct 2019 19:10
lbls1 wrote:
27 Oct 2019 18:19
I have heard of a lot of the Duals of that vintage having that problem. I had a similar problem, but my craft did not have the reverse play (probably a different motor).
What I did was actually nothing other than switching it from 33 to 45 and back but more often. Somehow the problem corrected itself. I believe that many turntables in this genre played primarily 33 rpm records, and the non use of 45's may have added to the problem of switching gears.

You could look into replacing the spring on the arm of the belt guide, to see if that will help. Good luck.
I just double checked and it look like the belt guide doesn't use springs to go between 33 and 45. I'll have to flip it over again and see what's going on inside the thing.
Wow I thought it did. Its been awhile since I looked at mine. Double check. Either that or a simple lube with household oil at a metal pivot point somewhere. Good luck.

lbls1
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Re: Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by lbls1 » 28 Oct 2019 03:34

Ok I looked at mine. Your turntable must be a different series. Mine is CS 1246 and the guide has a spring on the outside (I saw it myself). It could be that since yours is a later make (possibly) that a change in design may have eliminated that spring. Its funny that a lot of Duals have had the speed selection sticking issue, including mine.

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Re: Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by apastuszak » 28 Oct 2019 11:16

lbls1 wrote:
28 Oct 2019 03:34
Ok I looked at mine. Your turntable must be a different series. Mine is CS 1246 and the guide has a spring on the outside (I saw it myself). It could be that since yours is a later make (possibly) that a change in design may have eliminated that spring. Its funny that a lot of Duals have had the speed selection sticking issue, including mine.
The spring on the outside doesn't control the speed between 33 and 45. It controls the mechanism locking in when you turn off the unit.

I have a ton of belts coming in the next 2 weeks. I will test them all out and report back.

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Re: Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by lbls1 » 29 Oct 2019 00:51

Okay good luck. Let us know if it helps.

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Re: Dual CS1257 swiching speed between 33⅓ and 45 RPM.

Post by apastuszak » 29 Oct 2019 00:57

I plan to return anything that allows returns, and report back on what I found to be the best replacement belt for the 1257. Hopefully this will help someone farther down the line.

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