Xiaomi Vacuum Cleaner Charger PSU

[rtstorm]

Hello my vacuum cleaner dock died, 0V on output. I replace the caps but still no voltage. I found out that this resistor is broken (showing 0 Ohm) do know the value of this? Is this really 0 Ohm resistor?

[R_J]

That is a coil (L2) not a resistor, did you check the ac fuse?

[rtstorm]

Yes fuse is oke, i have ac voltage up to transformator

[R_J]

You should only have AC voltage going into the Bridge rectifier, after the bridge rectifier it should be DC voltage

[rtstorm]

Sorry this is what i ment, and than i have Dc up to the transformator

[R_J]

Do you have any DC voltage on the output (red and black wires) it should be around 20vdc
I found this site where someone else is working on one Зарядная док-станция для робота-пылесоса Mi Robot Vacuum Mop. Что внутри? (go-radio.ru)

[rtstorm]

I do not have any voltage on output

[R_J]

It is a simple smps circuit, If the mosfet is not shorted and R8,R9 are not open, it may be that U1 is defective. You could also try disconnecting the red wire that goes to the other board to make sure there is nothing shorted on the other board killing the 20vdc.
There is a small electrolytic next to U1, this cap is for the ic's VCC voltage, check the voltage ACROSS that capacitor, It's voltage will tell you the state of U1
Can you post the numbers on U1, you may need to clean the top with alcohol to see them.

other components to check are D1 and R1 and R2, these resistors are 1.5 MEG Ω each and sometimes one may go open.

[rtstorm]

R8,R9 are not open, when i disconnect the red wire i still have 0V output so no short on other board. Voltage across the small cap is 1.5V
U1 have mark: 362L49

[R_J]

The ic is a ON-BRIGHT OB2362, it needs at least 7 volts dc across the small (vcc) cap. so check if R1 and R2 are not open, they supply the initial vcc voltage, If they are ok and the cap you replaced is not bad, I suspect the ic is defective

I found this similar schematic which may help
Yor R1 and R2 would be the same as on the schematic R3 and R9; Your D1 would be D6 on schematic

[rtstorm]

Thank you, i check R1 and R2 and they are fine, also D1 is fine too. I think that the Ic is bad. I try ti freezee it with spray and i get 5V on output for a few seconds. This unit need to have 5V on standBy so i guess the faulr is in thet IC

[R_J]

R1 and R2 can be hard to check in circuit because of their high resistance value. Also chek that R13 is 2R2Ω

You can also check the voltage on R1 and R2 (you must use the main cap [-] ) for ground. the voltage on R1 will be full dc as measured on the main filter cap, it should drop to aprox half at R1 R2 junction.

[rtstorm]

I remove the R1 and R2 and test them separatly

[harp]

What is resistance on output capacitor, and what is resistance on small blue vertical capacitor near heatsink? Diode like D4 can die...

[rtstorm]

Resistance on output cap is arount 25kOhm. I disconnect the D4 and test it is ok.

[SapFirooz]

Try To check resistors to voltage! The resistor have two foots so chek first and second! Sometimes works!