Need help on how to test large inductor

[macattack600]

I am working on a Crest Ultrasonic cleaner , through the inside it leaked liquid on the corner PCB on just one almost C battery sized inductor with steel core. I've replaced diodes and transistors and the board powers the machine correctly but the bad inductor will burn if I run it more than 30 seconds. There are four inductors which feed each to one of the 4 transducers wired in series.

It seems that the inductor is prob a 20awg with what I would say at least 250+ turns with a metal core. (Looks like a speaker crossover inductor).

Could I test this to get a close enough value with something like this ?
https://www.amazon.com/Sinometer-VC6...ords=lcr+meter
or would I need something else , this meter starts at 2mH I think this would be ok given I unwound the bad inductor and got at least 250turns but the wire broke up and I could'nt properly measure more.

There is no schematic per pcb part number on the internet there is no
markings on the inductors . The company that manufactured this has no schematic due to being older model .

[Longbow]

Re: Need help on how to test large inductor

A few more bits of information could get you going on this project. Photos?
You can probably find schematics of similar cleaners that will be close enough to yours.
Are all the inductors driven by the same source, or by different sources? Inductance values on these things will likely be in the multiple Henrys, not critical and rewinding is a good possibility. What kind of transducers are used on this cleaner?

Check the frequency of operation first - that should be very easy. Remove the faulty inductor and compare the value with another good one. Or: make a guess at the frequency of operation - maybe 50KHz? Using formula for resonance, place a reasonable cap in series with the coil and manually sweep the network using an audio oscillator. (Most go up to 2 MHz) whilst watching for a resonant voltage peak.

Publish results.

[stj]

Re: Need help on how to test large inductor

if it's not open circuit, it does not smell burned, and the core is intact - it's probably fine.

it's only a coil of wire afterall.

[keeney123]

Re: Need help on how to test large inductor

I am working on a Crest Ultrasonic cleaner , through the inside it leaked liquid on the corner PCB on just one almost C battery sized inductor with steel core. I've replaced diodes and transistors and the board powers the machine correctly but the bad inductor will burn if I run it more than 30 seconds. There are four inductors which feed each to one of the 4 transducers wired in series.

It seems that the inductor is prob a 20awg with what I would say at least 250+ turns with a metal core. (Looks like a speaker crossover inductor).

Could I test this to get a close enough value with something like this ?
https://www.amazon.com/Sinometer-VC6...ords=lcr+meter
or would I need something else , this meter starts at 2mH I think this would be ok given I unwound the bad inductor and got at least 250turns but the wire broke up and I could'nt properly measure more.

There is no schematic per pcb part number on the internet there is no
markings on the inductors . The company that manufactured this has no schematic due to being older model .

So what type of transducers is it using? Perhaps some of the coil windings have shorted or are shorting. The insulation could of been compromised if you are using more than water in the cleaner and that got on the coil.

[Longbow]

Re: Need help on how to test large inductor

if it's not open circuit, it does not smell burned, and the core is intact - it's probably fine. it's only a coil of wire afterall.

Famous last words.

[R_J]

Re: Need help on how to test large inductor

Its a good idea to check the transducers, are those the piezo ceramic type? check them for cracks, if they are not cracked they should be ok, many times people drop parts into the tank and that can fracture the transducers.

[kc8adu]

Re: Need help on how to test large inductor

since you have already unwound it time to measure the diameter of the wire,get a roll of magnet wire,and start winding.measure the length of the sections as you unwind and break them.within a few feet is good enough.since it is crumbling as you unwind its probably toast pardon the pun.