Do you own a “speedy” Dual turntable? There is a well-known speed issue that affects SM-840 motors installed in specific belt-driven turntable models.
The speed problem is usually fixed by replacing the faulty SM-840 motor with an upgraded SM-860 motor, which are hard to find these days and quite costly.
But wait… Don’t throw out that old “speedy” SM-840 motor! Now there’s a simple fix that can restore your turntable to perfect operation without even removing the old motor.
The MSF-60 motor speed fix is a Do-It-Yourself kit, consisting of a tiny circuit board that remediates the speed problem with Dual SM-840 motors operating at 120V AC at 60 Hz. The MSF-60 works with the Dual 1249, 601, 510 and 502 turntables.
Affected turntables exhibit speed instability at startup, namely the 33-1/3 RPM rotation operates at double the speed. This “speed takeoff” occurs randomly and can be affected by any combination of line voltage, line frequency, sine wave phase, and mechanical load on the motor.
HOW IT WORKS:
A tiny microprocessor creates a timing pulse that injects a small load onto the motor for a short interval at startup. The load is controlled by a solid state relay and the circuit is powered by a self-contained miniature power supply. This startup pulse allows the motor enough time to properly synchronize and lock in the speed, thus preventing “speed takeoff”.
The new yellow, version 2.0 modification kit attaches to the underside of the deck plate with the included double-sided gel tape, and installs easily with just three wires. Our easy-to-follow installation manual in PDF format shows you step-by-step wiring guides for each turntable model.
Or, we can install the module for you for a reasonable fee, as well as any other turntable, tube audio, computer and electronic repairs and modifications you may have in the Toronto area.
Please Note: This Do-It-Yourself modification kit is easy to install, but is suited to technically-inclined Dual owners. The kit requires a certain knowledge of electronics to install, as well as soldering and schematic skills and a basic set of tools.
“I can attest that this board works perfectly, as I have had the pleasure of testing the first pre-production board on a sick 601 I have … I was well pleased with the results and can heartily recommend it!”
Former Assistant Service Manager
Noresco – Dual of Canada
“Just thought I’d let you know I installed the update today … my 1249 appears to work perfectly. The mechanism seems to work great, and the turntable speed is correct. Thanks for providing the kit and the hard work I’m suspecting you did designing it.”
PLACE AN ORDER:
All prices are in Canadian Dollars:
- The MSF-60 kits are $60.00 each
- Shipping to North America is $8.00
1. Be sure your platter drive belt is in new or good condition. A worn or stretched belt may affect the function of the module.
2. Please specify your turntable model number in the PayPal instructions box.
3. Please include your phone number (required for U.S. shipping).
** SOLD OUT **
We are currently out of stock of the MSF-60 Motor Speed Fix Kits. We will have more on January 20, 2024.
We ship by Lettermail to Canada and Small Packet Air to the US. In order to reduce cost, this economy service does not include tracking. Your order will take an average of 2-6 weeks to arrive. Please allow extra time due to COVID-19.
- The “speed takeoff” fault only occurs in 120V AC / 60 Hz model SM-840 motors, mainly from the American continents. The MSF-60 kit will have no effect on 50 Hz motors.
- The MSF-60 kit is specifically designed to remediate the “speed takeoff” fault. It will not fix other SM-840 issues caused by bad bearings, worn parts, bent shafts, etc.
- Proper operation of the MSF-60 kit is predicated on the motor having sufficient mechanical drag. Thus, it is important to use a platter drive belt in new or good condition. Old, worn-out, stretched rubber belts will be too loose and may prevent the MSF from correcting the motor speed each and every time.