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.
