MT-4 Mini-Sonic stopping - FIX
Aug 19, 2024 23:23:01 GMT -5
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mjflinty, AzRockGeek, and 6 more like this
Post by lou23464 on Aug 19, 2024 23:23:01 GMT -5
One of the older many Sonic units I have, with a blue case, began to randomly stop after 15 to 20 minutes of running.
Using an OHM meter to troubleshoot I discovered that the magnetic electrical coil would open once it heated up from operation.
Contacted Diamond Pacific and ordered a replacement coil part number 490-401796 for $55. This fixed the problem and the unit again has become a workhorse working better than a newer model mini Sonic.
Now for a little bit of technical info...
I unwound the bad coil. Down deep in its windings I found a bad burnt area where the intermittent was. Unfortunately the wire came off in pieces here and I was unable to measure it's total length. The magnet wire diameter is .35 mm.
Before I installed the new coil from Diamond Pacific I took inductance and resistance readings of the new factory fresh coil in case you want to rewind your own.
Inductance: 314 mH @ 1 kz
DC resistance: 26.85 ohms
Some theory:
The magnetic coil creates a magnetic field, pulling in the tumbler barrel steel mount, each time it receives a half-wave pulse from the SCR controller ( the part with the on-off switch and speed control knob). This occurs 60 times a second (60 hertz). This equates to a vibration frequency of 3,600 times a minute. (60 seconds in a minute x 60 pulses per second).
The SCR controller reduces or increases the width of this half-wave pulse effectively controlling the vibration energy.
Between the controller and the coil, on the white wire under the shrink tubing, is hidden a rectifier diode. The anode of this diode points towards the controller, the arrow or banded side of the diode points towards the coil. The purpose of this diode is to isolate the controller from the coil so when the waveform drops to zero between pulses, and the magnetic field in the coil collapses, it blocks inductive kickback from the collapsing magnetic field and protects the controller from the resulting high energy pulse. If you need to replace this diode a 1N4007 diode is a good replacement. Best to be careful in this area when cutting wires that are wrapped in heat shrink.
The controller is widely available if needed. From Diamond Pacific, partno 490-401996 for $35. Or, search for controller manufacturer partno KBWC-13K for $10 online elsewhere.
While replacing the coil I also installed the available tune up kit available from DP. This Mini-Sonic, though many years old, and a little beat up, is again working good as new!
Best,
Lou Reyna
Virginia Beach, VA
Using an OHM meter to troubleshoot I discovered that the magnetic electrical coil would open once it heated up from operation.
Contacted Diamond Pacific and ordered a replacement coil part number 490-401796 for $55. This fixed the problem and the unit again has become a workhorse working better than a newer model mini Sonic.
Now for a little bit of technical info...
I unwound the bad coil. Down deep in its windings I found a bad burnt area where the intermittent was. Unfortunately the wire came off in pieces here and I was unable to measure it's total length. The magnet wire diameter is .35 mm.
Before I installed the new coil from Diamond Pacific I took inductance and resistance readings of the new factory fresh coil in case you want to rewind your own.
Inductance: 314 mH @ 1 kz
DC resistance: 26.85 ohms
Some theory:
The magnetic coil creates a magnetic field, pulling in the tumbler barrel steel mount, each time it receives a half-wave pulse from the SCR controller ( the part with the on-off switch and speed control knob). This occurs 60 times a second (60 hertz). This equates to a vibration frequency of 3,600 times a minute. (60 seconds in a minute x 60 pulses per second).
The SCR controller reduces or increases the width of this half-wave pulse effectively controlling the vibration energy.
Between the controller and the coil, on the white wire under the shrink tubing, is hidden a rectifier diode. The anode of this diode points towards the controller, the arrow or banded side of the diode points towards the coil. The purpose of this diode is to isolate the controller from the coil so when the waveform drops to zero between pulses, and the magnetic field in the coil collapses, it blocks inductive kickback from the collapsing magnetic field and protects the controller from the resulting high energy pulse. If you need to replace this diode a 1N4007 diode is a good replacement. Best to be careful in this area when cutting wires that are wrapped in heat shrink.
The controller is widely available if needed. From Diamond Pacific, partno 490-401996 for $35. Or, search for controller manufacturer partno KBWC-13K for $10 online elsewhere.
While replacing the coil I also installed the available tune up kit available from DP. This Mini-Sonic, though many years old, and a little beat up, is again working good as new!
Best,
Lou Reyna
Virginia Beach, VA
