Help in identifying MOV rating.

[asimov_18]

Hwll All,
I was recently fixing a 500W UV lamp electronic ballast that is used with a mask aligner.
This unit blows up fuses. On opening and inspecting the unit I find this unit uses two MOV in serries and
both of these have failed. The MOV are shorted out and physically disintegrated with obvious burnout marking and case cracking.

Incidentally the marking on the unit is as follows.
MS32 or M532 (line 1)
20010 (second line)
4312 (third line)

I cant find this part number nor I am able to decipher the ratings from this cryptic marking.
Attaching the photograph for the same any inputs will be highly appreciated.

Warm Regards

Asimov

 

[asimov_18]

Hi All,
I found out about this device. This is not a MOV as initially thought but this is a Inrush Current Limiters by a company called Ametherm. availabel at mouser
with the part number MS32-20010.

 

[neonwarrior]

Hi Asimov, you must be careful if that inrush current limiter (thermistor) brake. You probably have a short circuit downstream that part.
You can measure with ohmmeter between one leg of thermistor on the PCB and ground ( or Line or neutral) you should trace the circuit a little bit.

 

[asimov_18]

Dear Nonwarrior,
Thanks for the reply and your inputs. Incidentally I had checked the the circuit post the inrush current limiter and had discovered faulty MOSFETS
where the gate drain and source had shorted out effectively destroying these inrush current limiters. Thanks again for the inputs.