LED driver board, orient electric, 7W

[claws77]

datasheet= https://www.alldatasheet.com/datashe...C/SIC9753.html
i have tried to make the schematic similar to typical application
A1 = varistor
V_C5 _measured wrt -ve = 57-60V pulsating DC, VDD_measured wrt GND_IC = 12-14, VDD_measured wrt -ve = 60-62V pulsating, V_Drain wrt -ve =309V,

1. L2 is unknown, how to measure inductance with multimeter?
2. what is happening after rectification and varistor? what does this IC do? how does it provide constant current ?
3. R8 36Kohm is to discharge the capacitor C5 100uF only, right?
4. how to test if this IC is faulty?

[stj]

it's an online buck convertor,
A1 is a VDR to supress spikes

R8 is to provide a load if the leds fail so the voltage doesnt spike really high,
you cant read the inductor with a multimeter

[claws77]

thanks, how to test if IC is faulty.

[stj]

test the leds and replace c4

[claws77]

LEDs are fine.
this is a bypass capacitor so can i replace it with any higher value for capacitance and rated voltage
the current one on board is 4.7uF and 50V

[claws77]

i have 4.7 uF and 400 V and 10 uF & 63 V

[stj]

10uf is better
and check the diodes
the fact it's pulsing means it's trying to run.

[claws77]

nothing

[claws77]

i have succesfully blown the input (AC) side of the rectifier.

[stj]

how?
is c3 shorted?

[claws77]

no, i was working on metal plate, and there was some movement and the live wire touched the plate and near the soldered joint and back plate of LED (heatsink) made a connection. i think.

R1, R2, L1, and the first LED(only) was blown(open) so i replaced them all only for them be blown again (this time i made sure everything was insulated) maybe something else is shorted too. hope its not the IC.

Can i not use this LED circuit without input filtering. if i am unable to find the right parts.

[stj]

the only input filtering is R2 and L1

[claws77]

my bad R1 is a fuse, kind off.

[CapLeaker]

If R1, R2 and L1 blow up all the time, either your bridge rectifier D1 to D4 is shorted or A1 is shorted. Check them out first. Sure you can take L1 out and solder an and replace R2 with a 1 Ohm resistor (fusible resistor fireproof) or similar.