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Marcel, i just looked through the other pictures of the other circuit board and saw that one board had several of these cap/Varistors on it. Can you locate one off those which preferably has the same number / letters as the burnt one and post a pic of the other side of a good one. This way I...

Marcel, i didn’t mean to ignore this vital question here, but I wanted to see first the cap/varistor. Because if it is only this part which went bad besides aging electrolytic’s then there is nothing to worry about. In either case, the burnt cap/varistor serve more or less the same function...

The PCB even though burnt seems to be ok. When you remove the electrolytic’s then you will be able to see the traces and continuity check them

Ok, the next thing then would be to remove the electrolytic’s since you had mentioned before that you had received replacements if I remember that correctly I would check the diodes etc on the other board now too

this damage is more consistent with metal oxide. It burns hotter then ceramics. Anyway, let’s say it’s a ceramic cap then it would be a 0.01uF 1000V 20% cap I cannot clearly locate the manufacturer of this cap - usually the letters gives you an idea unless that info was on the other side of cap

thank you Marcel. Quite a violent distraction. I was not able to clarify by the Markings if this is a varistor or ceramic capacitor yet However, the damage to the part is more inline with the way Varistors fail then Ceramic Capacitors. Ceramic Capacitors usually just blow a small hole on one...

Marcel, once you remove the part could you please check for continuity between both pins? Ceramic Capacitors can fail. They start decreasing their DC Resistance from near infinite Ohm down to full short. But this usually takes quite a while for this happen. A system with a failing ceramic cap...

Marcel, i still would like to see a picture of both sides of your failed part to see how it failed besides the obvious that it got hot Peter

Kurt, the one you got is Cermaic Cap, no question. Is there anywhere in your circuit a inrush limiter that your aware off? It is hard to believe that they have no inrush current limiting with those 12 large caps. The inrush current is pretty high when they are empty and the system first fires up

I would like to see the defective part

Marcel, Could you please desolder this part now and post a pictures of it from both sides? This way I can get better understanding of what actually happened. Since this part is directly next to the large caps it is most likely a inrush current limiter But I need to verify this

Inrush Current Limiters look the same as Varistors but are a NTC. Thought I had to clarify this

Is also used as transient voltage suppressor

A metal oxide varistor has usually a bulge on both sides when compared to a ceramic disc capacitor . your picture is not that clear, so we will find out if it is a ceramic capacitor or a varistor once you remove the part in question

this is probably a variastor and is used as inrush current limiter. This burning up of the Varistor indicates that the high voltage side has a severe short(s) to ground. At this point, any semi conductor, any capacitor in the HV part of this circuit is suspect. That’s pretty much a major repair...

I am glad you got them from arrow. I also use Future Electronics and Newark. I buy almost all semis from manufacturer (TI, STM etc) direct because of the cloning and counterfeit’s as to testing: in circuits continuity / diode against Ground or 0V plane on PCB and between pins of each semi Peter

great, they are of a better quality then the Panasonic but also almost twice as expensive. Glad you found some one who had stock. Mouser shows 0 stock with 200 on order Expected 21-Nov-22 And Digi Key shows 0 stock with 76 week lead time ARO I suspect that some of the power semi’s and maybe...

That’s correct for Audio DC Power supplies for sure, but here you would have to use the values for capacitance and working voltage from the currently installed caps, but you can choose any cap manufacturer as long as they fit the PCB pattern (lead spacing) and dimensions i just happened to open...

We at INOVA HIGHTECH Ltd. use these Electrolytic Capacitors (MIL-STD): The slightly lower cost and smaller footprint version is this here (Industrial Grade): Nichicon has the highest grade Electrolytic Caps for Industrial Equipment which are by far better but also more expensive then...

There might be a lot more wrong then the inductors. The large caps are probably all dried out as well. You would have to disassemble the entire unit and check all power semi conductors as well. What is the DC Resistance of your exciter coil?