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Chemistry Electronics Services
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Repair a W185 Branson Sonifier's transducer head,
the cell-disruptor's "converter" with the piezo disk stack


TYPICAL FAILURE:

The meter on the power unit shows power, but apparently with no ultrasonic output (no squealy noises, no effervescing from water-degassing effect.) Old failed cable? Or perhaps the main output horn was rotated while installing new tips, which tore loose the internal piezo terminals.

First verify that the power unit is actually working. Hold a scope probe one half-inch away from the transducer cable (or perhaps unplug the cable and hold the probe near the connector.) It's an unshielded high-voltage signal, so it's easy to pick up a 100mV signal through the air. Turn the power knob down, turn on the power switch and timer, and you should get a 20KHz square wave. The power knob should control the amplitude.


IF NO OSCILLOSCOPE AVAILABLE, at least open up the power supply and verify that the light bulbs (load resistance) will glow when the power knob is briefly turned to max. Also, the large electrolytic capacitor should have 24VDC on it with power set to minimum and no transducer connected. This voltage rises to 165VDC for maximum power knob setting.


Branson "Sonifier" cell disruptor model 185, W-185D


For model 185 Sonifier, use Ultrasonic Converter "model L" CL40194A (21KHz?)
(To open the converter, find four screws under round silver label, plus one screw for phenolic terminal strip)


For model W-200P Sonifier, converter "Model L" CL40443A


controls: power, timer, duty cycle, pulse/cont switch. The hidden "mystery knob" under the upper front edge is an inductor, tunes the main output from 19.5KHz to 20.5KHz (tweek the output for 20KHz piezo head)


"Model L" converter heads:
CL40433A (For the W200 power unit)
CL40194A (For the W185 power unit)
Tip-change, required wrench: Adjustable pin-spanner: 3/16" pin, range 3/4" - 2" (Williams No. O-471A or Stanley JC492 )






LINKS

PS
I haven't yet tried to replace dead (fractured) piezo elements. Probably these have a recommended torque-wrench setting. Are they tuned to resonanate with the ~20KHz drive? Probably, and in that case it may be possible to crank the torque higher while viewing node-trapped bubbles and listening for maximum sound-artifacts in a small beaker of water. That, and vary the tuning thumbwheel under the top edge of the front panel. If possible, adjust transducer-bolt's torque so the maximum effect occurs in the center of tuning range.


Created and maintained by Bill Beaty.



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