Samsung Mobile Phone Charger Repair

[BoonChai]

Hello there,
Can someone please help me to repair my charger?

When I switch on, the charger flash the spark and not charging anymore.
And I got the burnt smell.

After open the charger, I don't see any physical damage or burnt mark on circuit board.
I took out all 3 capacitors and tested with meter and all are in good condition.
And diodes too.

I measure the output voltage and voltage is around 1 volt in ON & OFF, ON & OFF, ON & OFF ....... condition.
which is causing that and how to repair?

I'm not good at electronics.
So please bear with me and guide me step by step.




Thanks in advanced.
Lim

 

[Willen]

Can you find the new same type of 8 pin IC as in your charger supply has to replace? It seems a simple circuit all controlled by the chip so maybe problem is in there. Did you test the rectifier bridge too (back side)?

 

[BoonChai]

Thanks Willen

I'm afraid that I couldn't get that IC because there is no information printed on.
I measure the rectifier and the voltage is around 50 then down to 30, then up to 50 and down to 30 ... like that

 

[absf]

Here are some more info for the samsung charger. The author also drew the schematic at 4:55

https://www.ifixit.com/Guide/Samsung+USB+Charger/17367

BTW, how did you measure the capacitors? Did you measure the ESR?

Allen

 

[unclejed613]

if the charger is pulsing, there's something shorted on the secondary side

 

[BoonChai]

Here are some more info for the samsung charger. The author also drew the schematic at 4:55

BTW, how did you measure the capacitors? Did you measure the ESR?

Allen

Thanks Allen absf

I took out from the circuit and tested with normal analog multimeter. Short the both terminal of capacitor, switch the meter to x1K ohm and connect capacitor terminal.
The meter pointer go to right and slowly return to left start point.
I don't know how to measure ESR.

if the charger is pulsing, there's something shorted on the secondary side

Thanks unclejed613
Could u please tell me more details about where is shorted at?

 

[unclejed613]

it could be a shorted diode. you said it was going to 1V when it pulses. was that with or without a load connected?

 

[BoonChai]

it could be a shorted diode. you said it was going to 1V when it pulses. was that with or without a load connected?

Thanks unclejed613
That condition is without load.
I tested the only 1 ZD near at the USB port. I thought that was little faulty. Because when I measure with meter, 1 direction gave me little resistance. That means faulty, right.
So, I replaced with new 1 and the result is the same.