Checked all the components. This is simple circuit only one transistor and several diodes, four capacitors and number of flame-proof resistors. I did use capacitance meter to check actual value of these capacitors (three caps is polyester and one ceramic disc, none have electrolytic).
When working properly the liquid surface should be jiggling vigorously which it did intermittently, all I get is very faint shimmer (most of time). Twice time I had had unit's liquid surface jiggling with vigor and I put test objects to test and after withdraw it, just barely a shimmer. And other time was jiggling merrily then it suddenly flattened out to a faint shimmer. Dang.
Measured 30-33KHz with my fluke multimeter (it can measure up to 100KHz and had no problem seeing 15.7KHz before on CRT tv as well as 31-33KHz CRTs.) , should be 55KHz oscillation riding on 30hz bursts (which is correct on scope but oscillation is not at 55KHz) because of one diode supplying AC pulses to the oscillator circuit. I even moved the wire on the transducer with new spot of silver bearing solder, just in case.
I even exchanged ceramic disc that measured 360pF (should be 330pF (code 331) with no difference.
Then what now? Transducer shot? This one is solidly bonded to the pot's bottom. Note I always kept liquid filled in the pot while testing runs and probing it's innards.
Background: when unit came in dead, all it had was open 1 Ohm 1W resistor, not even overheated at all, fuse intact. That feeds 115VAC thru this resistor to the one diode (forward-biased) feeding half the sine waveform to rest of the circuit.
Please talk.
Cheers, Wizard
When working properly the liquid surface should be jiggling vigorously which it did intermittently, all I get is very faint shimmer (most of time). Twice time I had had unit's liquid surface jiggling with vigor and I put test objects to test and after withdraw it, just barely a shimmer. And other time was jiggling merrily then it suddenly flattened out to a faint shimmer. Dang.
Measured 30-33KHz with my fluke multimeter (it can measure up to 100KHz and had no problem seeing 15.7KHz before on CRT tv as well as 31-33KHz CRTs.) , should be 55KHz oscillation riding on 30hz bursts (which is correct on scope but oscillation is not at 55KHz) because of one diode supplying AC pulses to the oscillator circuit. I even moved the wire on the transducer with new spot of silver bearing solder, just in case.
I even exchanged ceramic disc that measured 360pF (should be 330pF (code 331) with no difference.
Then what now? Transducer shot? This one is solidly bonded to the pot's bottom. Note I always kept liquid filled in the pot while testing runs and probing it's innards.
Background: when unit came in dead, all it had was open 1 Ohm 1W resistor, not even overheated at all, fuse intact. That feeds 115VAC thru this resistor to the one diode (forward-biased) feeding half the sine waveform to rest of the circuit.
Please talk.
Cheers, Wizard
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