Power board using LNK304PN not giving output.
The whirlpool washing machine display is blank.When checked the power pcb, the power resistor burnt(value may be 100 ohm, 2W).Even after replacing it with normal one, it again got burnt. The DC o/p is not available. The Drain and source pins show around 35 ohm value. what is wrong with the board? kindly suggest.
Comments
as per ur advice u have mentioned conveter failed.Do u mean the diodes in series with resistor to rectify the ac?
Also as per the data sheet, it has provided as the on resistance between drain and source is around 30 ohm. but this value i can measure. still any chance of LNK304 failure.? pl suggest...
30 ohm in data sheet is RDSon when internal MOFET is switched on. When not operating device should have much higher resistance reading with ohmeter. It is likely the device(LNK304) is damaged
Kindly clarify me, what you like to say as converter. Whether LNK 304 or mains input rectifier diodes or any other thing?
It is likely LNK304 is damged. It is unclear whether it was the root cause of failure
This circuit uses 2 opto couplers 817B,817C. In shop they tell both are same.For checking this ,If I am right, the forward led should show in diode mode as diode. the collector emitter should be open or 1k? pl suggest me.
LED diode voltage is about 1V. E to C of opto transisor should read very high resistance with positive lead of ohmeter on collector. Opto's need to out od ckt to test.
thanks for suggestions. finally i was able to bring the washing machine to working condition. my optos were good. the resistor and LNK304PN change did all good.
once again thanks a lot.
Converter and LNK304 is damaged. I do not know what could have caused the converter to fail.