Hi folks, looking for help fixing the charger - it's not about the money at this point, but understanding why
The closest similar schematic I found is for the 115(4A) version, mine is 112 (2A)
I marked all parts replaced in red
Other pics are the actual PCB

I dug through the entire high-voltage part - from diodes and power field effect transistor to Zener diodes, resistors and optocouplers... individually all the parts are intact (I unsoldered and checked and back), but the PWM iw1710-01 doesn't start. 8...10 volts appear on the power supply (it constantly oscillating in this range, the same voltage on pin 3 (Vin). The Zener diode and transistor, the capacitor through which V goes to pin 8 have been checked - everything is intact.
I replaced the PWM with a new one - still same, it does not start. Something "holds" the start. What? I have run out of thoughts ... what else to check? Yes, if you cut off the low-voltage part immediately after the transformer , and supply 24V there from another power supply - charging works, blinks, charges .. everything is fine on the low side .....
What "holds" the PWM from starting?

EDIT: One more thing I discovered is that when using the 24V bench power supply on the charger part the optocouplers PC1 and 2 (3 is not present in the DBC112 version) have 0.98V on the LED. When I reconnect the charger to 120V (the bench 24V power supply not connected) it starts charging and stops after 2 or 3 blinks. After that the PC1 has 1.2V on the LED and PC2 only 0.2V so I presume it disables the power supply controller chip ? But why?

Can someone please help me to understand why is PC2 disabling the charging? (I presume that is the case)

Thanks!

 

Did you check D21 for short circuit?

 

Did you check D21 for short circuit?

Thanks for reply! Yes I did, even took it out for the test and it's working as it should using multimeter diode check and passed using Multifunction TC1 tester as well ( I know cheap device but I presume diode test is not that complicated)

Just out of curiosity, would you know what is the PC2 monitoring in the circuit?

Thanks

 

Just to update, problem solved.
I ordered the 1710-01 (10x) from AliExpress, never again bad chips.
After ordering from reliable source all working fine.