Hoover HPI430BLA/1 induction hob repair

[chema.rb]

Hi!

Half of my Hoover induction hob is not working. One of the control boards seems to be the problem:




R3 looks cracked and open circuit. Might it be that simple?

[T3sl4co1l]

Yeah, seems suspicious.  Ohm it out, and everything after it.  Why did it fail?  Perhaps its load failed shorted -- I would hazard a guess, the axial diodes nearby are rectifiers for the nearby small HV electrolytic, and the DIP is a TinySwitch or something like that, and the E-core part is a flyback transformer; and this is all for LV control supply.  Of those, the regulator (the DIP) would be the most likely culprit?

Tim

[perieanuo]

R3 is series limiting resistor for some voltage filtered with EC8 which in his turn makes another voltages with the transformer near him MD-EE19B, some smps I guess
so yes, no R3, no 5V and 18V voltages marked on bottom side
resolder well all current paths, like D3 and so on

[chema.rb]

Yes, is an SMPS, the DIP next to it is an ST Viper12A. Can't find any obvious short, I will replace the resistor (is a wire wound one) and see if it comes back to life.

[perieanuo]

check also for short the EC8 rails and around that viper, the resistor died of old age, bad design (my favourite) or short between those rails

[chema.rb]

Thanks,

Gave it a go with a 2W resistor, and it blew straightaway. I have been measuring the caps and the test fine, but it seems the secondary of the transformer is shorted (measuring 0.1 ohm).

[T3sl4co1l]

The transformer will tend to have low resistance.  More likely one of its outputs has a shorted load?

Tim

[perieanuo]

0.1 ohm on secondary winding is normal.
usually is the smps acting abnormal, like dead/shorted viper (my first doubt)
anyway, check the smps outputs for shorts (diode d4 and diode from his left, rails 5V and 18V (maybe you got 18V shorted, like dome dead inverter on tis rail)

[chema.rb]

I've been testing caps, the 7805... everything measures fine. Everyting points to the VIPer12A.