After having rescued a few turntables, mostly direct drive models including Dual 721 and 1229 idler and passing them on to fund the hobby, I ran across a pristine looking Dual 1249. It didn’t power up, and after replacing the burst start capacitor and cleaning the contact points, I found out about the SM840 motor problem.
The base has a brushed aluminum veneer that is in great condition.
I mounted an AT140LC cartridge and, boy, does this turntable sound good!
Definitely the sweetest sounding turntable I have had since selling my early Linn LP12. Maybe even including the Linn.
The start up speed problem has been reduced dramatically by selecting 45rpm, manually placing the tonearm in position, and prior to lowering the arm, select 33-1/3 rpm. Works over 90% of the time.
Peter
The base has a brushed aluminum veneer that is in great condition.
I mounted an AT140LC cartridge and, boy, does this turntable sound good!
Definitely the sweetest sounding turntable I have had since selling my early Linn LP12. Maybe even including the Linn.
The start up speed problem has been reduced dramatically by selecting 45rpm, manually placing the tonearm in position, and prior to lowering the arm, select 33-1/3 rpm. Works over 90% of the time.
Peter
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Congrats to this fine turntable! I'm still searching for a 1249, hoping to find any in a similar condition like your's.
Your startup issue seems to be a lose belt. Ever tried to replace it?
Best regards!
Your startup issue seems to be a lose belt. Ever tried to replace it?
Best regards!
I have not installed a new belt. Besides changing the motor to an SM860-1 version, or the stator, I read somewhere that a shorter (tighter) belt may help the startup problem.
However, since I never use the auto start feature, I am quite happy to continue with the startup procedure mentioned above.
Hope you are able to find a nice 1249. It is a sonic gem.
Peter
However, since I never use the auto start feature, I am quite happy to continue with the startup procedure mentioned above.
Hope you are able to find a nice 1249. It is a sonic gem.
Peter
What's that SM 840 motor problem? Never heard of it before. This motor was installed not only in the 1249, but also in the 1237/1239 family of turntables which were installed into consoles (radio, amplifier, turntable, sometimes even a cassette deck in one unit) in large quantities without any known specific issues, at least at our side of the Atlantic Ocean.
Best regards!
Best regards!
Apparently the 840 motor, when operating on 120v, 60cycles, as in the USA suffers some sort of problem with one of the poles causing the motor to start at approximately twice the normal speed, resulting in the platter spinning at approx 60rpm instead of 33-1/3. It is quite a common problem, and Dual offered a recall years ago to upgrade the motor to an 860 variety.
As I'm also participating in a German board dealing with Dual turntables, I did some research for you with the following results:
- SM 840 was the first Dual shadow pole synchronous motor for belt drive TT's. It was introduced with the 1249 TT which was a jubilee model (50 years of Dual) in 1975.
- Later belt drive TT's, as the 1237/1239 family of smaller TT's with 11" platter, featured the SM 860-2 or SM 860-4 motor. So I was in an error with one of my previous posts. I beg your pardon!
- Both the SM 840 and SM 860 motors featured a four pole stator and an eight pole aramture, running at 750 rpm (50 Hz) or 900 rpm (60 Hz) respectively.
- Both motors are mechanically interchangeable, at least as complete units each.
- Both motors mainly differ in the following: Stator #234449 and armature #234450 in the SM 860, stator #241569 (SM 860-2) or #242587 (SM 860-4) and armature #241571 in the SM 860 motors respectively. These components, as any others, are interchangeable, but stator and amature must be combined from the same type of motor.
- The double speed issue is known here as well, but it appears to become an issue mainly in 60 Hz grids. There's also an issue in the SM 840 with their magnet rings falling off the armature from time to time and leaving them asynchronous motors. The SM 860 motors are improved versions without these problems.
Best regards!
- SM 840 was the first Dual shadow pole synchronous motor for belt drive TT's. It was introduced with the 1249 TT which was a jubilee model (50 years of Dual) in 1975.
- Later belt drive TT's, as the 1237/1239 family of smaller TT's with 11" platter, featured the SM 860-2 or SM 860-4 motor. So I was in an error with one of my previous posts. I beg your pardon!
- Both the SM 840 and SM 860 motors featured a four pole stator and an eight pole aramture, running at 750 rpm (50 Hz) or 900 rpm (60 Hz) respectively.
- Both motors are mechanically interchangeable, at least as complete units each.
- Both motors mainly differ in the following: Stator #234449 and armature #234450 in the SM 860, stator #241569 (SM 860-2) or #242587 (SM 860-4) and armature #241571 in the SM 860 motors respectively. These components, as any others, are interchangeable, but stator and amature must be combined from the same type of motor.
- The double speed issue is known here as well, but it appears to become an issue mainly in 60 Hz grids. There's also an issue in the SM 840 with their magnet rings falling off the armature from time to time and leaving them asynchronous motors. The SM 860 motors are improved versions without these problems.
Best regards!
Very interesting and many thanks!
I have read that the SM860-1 and possibly SM860-5 motors have compatible bolt patterns for installation in the 1249 and that motors from the 1237 do not fit.
Mine has not failed to switch from 45rpm to 33-1/3rpm every time for the last several days......and it sounds great with the AT140LC.
I have read that the SM860-1 and possibly SM860-5 motors have compatible bolt patterns for installation in the 1249 and that motors from the 1237 do not fit.
Mine has not failed to switch from 45rpm to 33-1/3rpm every time for the last several days......and it sounds great with the AT140LC.
You can swap the upper end bellies that carry the mounting bolts. They're compatible between all of these motors.
Best regards!
Best regards!
Tonearm auto set down problem
I am in the final throes of refurbishing another 1249 and I’m stumped by, when starting in auto mode, the tonearm moves smoothly(after the usual pause) to the correct position over the lead in section of a 12” record, but just has the tonearm begins to lower, it moves abruptly about 1/2” towards the spindle.
All other functions in auto and manual work perfectly. A new steuerpimpel has been fitted.
Anyone had a similar problem or knows where to look?
Thanks
Peter
I am in the final throes of refurbishing another 1249 and I’m stumped by, when starting in auto mode, the tonearm moves smoothly(after the usual pause) to the correct position over the lead in section of a 12” record, but just has the tonearm begins to lower, it moves abruptly about 1/2” towards the spindle.
All other functions in auto and manual work perfectly. A new steuerpimpel has been fitted.
Anyone had a similar problem or knows where to look?
Thanks
Peter
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Hi Peter,
did you observe the fin like main lever's plane which presses and moves the steuerpimpel ? There mustn't be any grease. Did you clean it?
Best regards!
did you observe the fin like main lever's plane which presses and moves the steuerpimpel ? There mustn't be any grease. Did you clean it?
Best regards!
Hello Kay...thanks for the response.
Yes, the textured surface of the main lever is clean. The steuerpimpel I used is quite a soft rubber. Maybe I will fabricate one from a little stiffer material such as the white core of coax cable.
When the tonearm makes the final 1/2” movement toward the spindle, it is very abrupt. Certainly not a slow sliding motion.
Peter
Yes, the textured surface of the main lever is clean. The steuerpimpel I used is quite a soft rubber. Maybe I will fabricate one from a little stiffer material such as the white core of coax cable.
When the tonearm makes the final 1/2” movement toward the spindle, it is very abrupt. Certainly not a slow sliding motion.
Peter
Hi peter,
that's exactly how I do my steuerpimpels 😀! I cut 4 millimeters of the core isolation, so I have a cylinder of 4 mm diameter and 4 mm length. Then I drill 2 mm deep into the center, using a 2 mm bit. That's all, and these pimpels work perfectly!
Best regards!
Dual 1249 was the first TT I ever bought! Crazy Eddies in the Bronx, right on Fordham Road! It didn't make it past my #1 son's teen years.
The 1249 appears to be a fine player! It is Dual's biggest belt driven record changer and was only made in 1975 to celebrate their 75th anniversary.
Best regards!
Best regards!
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