Hello
I have NC-SSC05GNT charger that blow up the fuse in house. I wrote it because I dont know what to do next. I opened the charger and there was fired fuse and damaged wiring in the main transformer(primery side). I repaired that wiring(burning was on outside). The damaged wiring was only used as a power supply of driver FA5510.

After repair main transformer and replacement one rectifer diode I connected all with 100W bulb(no electronics in bulb). Unfornatelly if main transistor starts switching that makes short circuit for two seconds- I dont know why with such long delay because the driver FA5510 have a overcurrent protection. On 21 page in datasheet of FA5510 is schematic - most of it is correct with my NC-SSC05GNT(only primary side).

Things I have checked
-main cap is charging to 350V. Capacity measured with simple meter 88uF normal is 100uF. The voltage drops to 90V if main transistor switching.
-all tranzistors
-FA5510 - I connected external power supply(15V), if I make short circuit insted of transoptors the power consumption drops(so no damaged)
-on the secondary side od the charger is no short circuits but cap is charging only to 10V(should charging to 40v)
-I measured on secondary wiring of transformer an amplitude reach 170v and falls(cyclic)
-the wiring of transformer have full connections but I dont know how to check the internal damage.

If someone have any idea what to do or measure next I will be very grateful. Sorry for my bad english I didnt use it for years.

 

Try the charger with the transformer secondary disconnected, see if it performs normally or blows the fuse.
And correct secondary voltage.
Max.

 

Thanks for your reply. I tried it and its overcurrent for two seconds and overcurrent protection of FA5510 turn off the switching. I also tray without the transformer and there was no short circuit(the QPFC transistor is not the reason of the short circuit). I always testing the charger with serial bulb 200W to avoid blow up the home fuses and mass destruction on the pcb. The bulb have full brightness when transistor stars switching. I must be very carefully because this elements are rare.