Converter In-Rush Thermistors etc, UPDATE -4
UPDATE on 17 Nov, Update 2 on 22 Nov, Update 3 on 16 Jan 14, Update 4 on 19 Oct 14. --------------- In a recent thread there was mention of how you can wreck your gizmo (in my case a converter) ...
Forum Discussion
Salvo wrote:
This is obviously a design flaw. I believe everybody in the converter business uses a NTC thermister to limit turn-on current.
Overvoltage has nothing to do with this failure. The device is not a transorb.
Sal
That's why I suggest trying a more gradual power cycling first to see if that helps. If not, then perhaps a design flaw. A hot thermistor will have very low resistance, and so will be susceptible to very large surge currents passing through it - which it will likely not be able to tolerate on a repeated basis. The caps may be discharging much faster than the thermistor is cooling, presenting a large surge next time the converter is turned on.
An overvoltage event will increase the peak surge current, and may overstress the thermistor.
