Dual 1229Q Rebuild...from "Want to see a disaster..."
- Thread starter ArDrakho
- Start date
Last thing this weekend was to clean up the platter. I used Noxon 7 to remove the varnish and stains from the center washer. Some light scrubbing was necessary to remove the more stubborn varnish...but it is now bright and shiny.
Then using soap and water, I cleaned the rubber mat and its grooved threading with a toothbrush. I removed grease and oil stains...along with some dust buildup in the threads. I cleaned the mat twice...now it is darked and cleaned...
Then using soap and water, I cleaned the rubber mat and its grooved threading with a toothbrush. I removed grease and oil stains...along with some dust buildup in the threads. I cleaned the mat twice...now it is darked and cleaned...
NoTransistors
Dual Turntables Super-Restorer
Do you understand the theory behind the weight's design?
There is a fixed weight, just like any other, and this one set into a rubber isolator. It is for arm resonances and obvious counterweight duty.
Then there is the bouncing weight. It is supposed to vibrate 180 degrees opposite from whatever chassis vibrations make their way to the arm, thereby cancelling them out.. See if you can replicate the entire broken spring by using a piece of the return spring from a tape measure. The curve in the factory spring must be duplicated, as one of the two screws that can be gotten to from the back of the weight is to adjust the height/levelness of the bouncing weight. The screw uses the curve for the adjustment. Or just find a better weight assembly. Remember that the 701 weight may look less cool, but has the same innards. This is what I have on my 1229Q, only because I saw that it looks better on it than your 704/721 weight does. BTW, the 704 and 721 weights seem to have different-length shafts. The longer of the two may cut the arm wires. I hack-saw the longer shaft to prevent this. Having fun? Are we there yet?
There is a fixed weight, just like any other, and this one set into a rubber isolator. It is for arm resonances and obvious counterweight duty.
Then there is the bouncing weight. It is supposed to vibrate 180 degrees opposite from whatever chassis vibrations make their way to the arm, thereby cancelling them out.. See if you can replicate the entire broken spring by using a piece of the return spring from a tape measure. The curve in the factory spring must be duplicated, as one of the two screws that can be gotten to from the back of the weight is to adjust the height/levelness of the bouncing weight. The screw uses the curve for the adjustment. Or just find a better weight assembly. Remember that the 701 weight may look less cool, but has the same innards. This is what I have on my 1229Q, only because I saw that it looks better on it than your 704/721 weight does. BTW, the 704 and 721 weights seem to have different-length shafts. The longer of the two may cut the arm wires. I hack-saw the longer shaft to prevent this. Having fun? Are we there yet?
I would think that the spring parameters are critical to the ability to cancel resonance or to soften transient changes in tonearm angle (warped records?.) If you change the spring in any way by making it more stiff or less stiff or change the weight attached that you will change the frequency at which that weight will swing. A stiffer spring oscillates faster - all other parameters being equal. I.e. Gluing or otherwise patching the spring can affect the original design.
But having said all this you may never notice the difference. I wonder if there aren't easier ways to deal with the challenges such designs are meant to resolve. (I can't believe though that such a big weight and spring setup is going to cancel resonance which is a high frequency behavior. Such weights/spring combinations will have a low natural resonant frequency. Think small clock pendulum. I would have though damping material or different tonearm design would have worked better for real tonearm resonances.)
I have a Dual 604 with a dangling counterweight. The implementation on the 604 is different and has its' own set of problems. I had to fix it because glue used in the original design had let go. Seems to be a common theme with some of these Dual's with these dangling counterweights. Your's seems to be a more mechanical connection to the weight than just glue though. Perhaps a better design except for yours really broke.
But having said all this you may never notice the difference. I wonder if there aren't easier ways to deal with the challenges such designs are meant to resolve. (I can't believe though that such a big weight and spring setup is going to cancel resonance which is a high frequency behavior. Such weights/spring combinations will have a low natural resonant frequency. Think small clock pendulum. I would have though damping material or different tonearm design would have worked better for real tonearm resonances.)
I have a Dual 604 with a dangling counterweight. The implementation on the 604 is different and has its' own set of problems. I had to fix it because glue used in the original design had let go. Seems to be a common theme with some of these Dual's with these dangling counterweights. Your's seems to be a more mechanical connection to the weight than just glue though. Perhaps a better design except for yours really broke.
Getting there
It is a simple design but it is elegant in action. I am fully aware that mine will not fully function as new because of my repair job...but it will function. I did search for 701 and 704 counterweights...but I located this 721 instead. I am still keeping my eye out for an undamaged counterweight. Thanks for the info!! Came across an article that also explains the counterweight and has cross-sections of it. Nice article--very informative.
1) Time start where I removed that the last assembly. In preparation for installing the Tonearm Plate assembly, I am re-positioning the Rest Lever (86),
Then re-assemble the Tonearm Plate Cover (68) & Locating Lever (70):
Make sure you "hook" the Rest Lever with the Locating Lever when you are positioning the Tonearm Plate Assembly.
Once the Tonearm Plate Assembly is in position, place the Anti-Skate Knob (84) into its position and, in the underside, re-assemble the with Curve Washer (258)...
Note: From my disassembly notes, re-align the "back dot" from knob on the upside to the "hole" in the curve washer underneath.
Then re-assemble the Tonearm Plate Cover (68) & Locating Lever (70):
Make sure you "hook" the Rest Lever with the Locating Lever when you are positioning the Tonearm Plate Assembly.
Once the Tonearm Plate Assembly is in position, place the Anti-Skate Knob (84) into its position and, in the underside, re-assemble the with Curve Washer (258)...
Note: From my disassembly notes, re-align the "back dot" from knob on the upside to the "hole" in the curve washer underneath.
Switching to the upper side in preparation for the Tonearm Assembly, re-installing the Tonearm Rest Assembly (66), Rest Web (54), & Rest Stud (52)...
Next is to re-insert the Tonearm Assembly (73), ...following the instructions in the service manual...
And secure the assembly with its Tonearm Bearing (69) & Hex Nut (71).
Note: do not forget the spring...
Next is to re-insert the Tonearm Assembly (73), ...following the instructions in the service manual...
And secure the assembly with its Tonearm Bearing (69) & Hex Nut (71).
Note: do not forget the spring...
Time to re-install the Tonearm Plate (201) and the Lifting Plate (203)...but do not secure it yet...
Go to the upside and reinstall the Positioning Sleeve (200), "C" Washer (199) and the Guide (198):
Then, secure the Tonearm Plate (201) and the Lifting Plate (203) assembly.
Go to the upside and reinstall the Positioning Sleeve (200), "C" Washer (199) and the Guide (198):
Then, secure the Tonearm Plate (201) and the Lifting Plate (203) assembly.
Attachments
Next to re-install is the Cueing Assembly + Lever (216)...I placed the Damping Plate (221) down first with the Lift Cam (220) and the Torsion Spring (219), working together into position. Once there, secured it.
Using a toothpick to "twist" the hole in the Lift Cam to make the screw hole available, I installed the Lift Lever (64). Then tested it...
Using a toothpick to "twist" the hole in the Lift Cam to make the screw hole available, I installed the Lift Lever (64). Then tested it...
I installed the Bearing Pillar (208). I thoroughly cleaned the Cam Cycle Gear (165) and lubricated the gear tracks, where I installed the Cam onto the Bearing Pillar...
I re-assembled the Bearing Suport (171) and Cam Rocker (173) into one unit...and placed itno position...
Then I re-installed the Start Bracket (248)...with its Tension Spring (251)...
I re-assembled the Bearing Suport (171) and Cam Rocker (173) into one unit...and placed itno position...
Then I re-installed the Start Bracket (248)...with its Tension Spring (251)...
Shifting back to the tonearm area...it is time for the Locking Slide (212) and Equalizing Arm (210) re-installation...
Note: do not forget the Tension Springs (237 & 240).
Next for some easy work, I re-installed the Positioning Lever (276) with its respective Switch Lever (51)...do not forget to align the lever afterwards:
I re-installed the Pawl (273) and secured it with the Threaded Bolt (256).
Then, I placed the Locating Slide (255) into position and secured it by re-attaching the Tension Spring (262).
Note: do not forget the Tension Springs (237 & 240).
Next for some easy work, I re-installed the Positioning Lever (276) with its respective Switch Lever (51)...do not forget to align the lever afterwards:
I re-installed the Pawl (273) and secured it with the Threaded Bolt (256).
Then, I placed the Locating Slide (255) into position and secured it by re-attaching the Tension Spring (262).
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NoTransistors
Dual Turntables Super-Restorer
All these parts have names? 
Next thing to re-install is the Switch Arm (188). Attach the Torsion Spring (187) into the Switch Arm. Carefully wind up the Torsion Spring, holding the spring in its wound up tension, "hook" it as in the picture to maintain its tension and then carefully position the entire assembly and hold it there. Install the Grooved Shaft (192) and secure the entire assembly with the "C" Washer (194).
Next, I re-installed the Function Arm Start Lever (196) with its Switch Lever (50). As noted before, do not forget the align it the lever later.
Do not forget to re-attach the Tension Spring (252).
Then, I installed the Rocker (257), which makes contact to the Cam Cycle Gear...
Do not forget the Compression Spring (261) before you install the "C" Washers (260 & 263).
Next, I re-installed the Function Arm Start Lever (196) with its Switch Lever (50). As noted before, do not forget the align it the lever later.
Do not forget to re-attach the Tension Spring (252).
Then, I installed the Rocker (257), which makes contact to the Cam Cycle Gear...
Do not forget the Compression Spring (261) before you install the "C" Washers (260 & 263).
Now I was ready for the Main Lever (184) re-installation. First I positioned and aligned the Bushing (214), Leaf spring (181), and the Connection Lever Support (215) and secured them with the Joining Screw (182).
Then I attached the Main Lever (184) to the Connection Lever Support. Keeping the tip of the Main Lever in the Cam Cycle Gear, I manipulated the tip of the Linking Lever (270) into the wide-side of the Main Lever. (This is important because this action involves the tonearm cueing movement.)
Next, I installed the Switch Lever (195). First I installed the Bowed Lock Washer (190) upon the Switch Arm and its Grooved Shaft.
I positioned the Switch Lever by placing it upon Switch Lever and "connected" to the Function Arm Start Lever. Lastly, I secure it with a "C" Washer (193).
Then I attached the Main Lever (184) to the Connection Lever Support. Keeping the tip of the Main Lever in the Cam Cycle Gear, I manipulated the tip of the Linking Lever (270) into the wide-side of the Main Lever. (This is important because this action involves the tonearm cueing movement.)
Next, I installed the Switch Lever (195). First I installed the Bowed Lock Washer (190) upon the Switch Arm and its Grooved Shaft.
I positioned the Switch Lever by placing it upon Switch Lever and "connected" to the Function Arm Start Lever. Lastly, I secure it with a "C" Washer (193).
