Repaired a W185 Branson Sonifier's transducer head,
the cell-disruptor's "converter" with the piezo disk stack

TYPICAL FAILU

The meter on the power unit shows power, but apparently with no
ultrasonic output (no squealy noises, no effervescing from
degassing effect in water.)

More info:

http://staff.washington.edu/wbeaty/chem_branson.html

I've now repaired more than one of these things. Typical failu the main steel "horn" gets rotated while replacing the narrow tips, and it tears the internal connections right off the main piezo transducer. If it didn't pull the solder-tinned tabs off the piezo stack itself, then it's possible to get in there with a long soldering iron and re-attach.

Note that it usually has two piezo disks in a stack, with the "hot" lead connected to the middle electrode in the stack, and the outer piezo electrodes going to ground.

First verify that the power unit is actually working. Hold a scope probe a 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 controls 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 max. power-knob setting.

Branson "Sonifier" cell disruptor model 185, W-185D For 185 21KHz...

Transducer is "Ultrasonic Converter" model-L, a CL40194A (Four screws under label, plus one screw for phenolic terminal strip)
For W-200P Sonifier, converter "Model L" CL40443A

(controls: power, timer, duty cycle, pulse/cont switch. The hidden thumbwheel "mystery knob" is a variable inductor, tunes from 19.5KHz to 20.5KHz (tweek the output for max effervescing from piezo head into water.)

"Model L" converter heads:
CL40433A (For the W200 power unit)
CL40194A (For the W185 power unit)

USE THE CORRECT WRENCH to replace tips: Adjustable pin-spanner: 3/16" pin, range 3/4" - 2" (Williams No. O-471A about $30 each) Two wrenches, or one wrench and a vise. Don't let the steel horn rotate in the cylindrical housing.