I'm attempting to repair a 12V 10A switching power supply. Although I have bought a new replacement but i think it's good to have such beefy supply handy.
During the initial stage of repair the board was having fuse and switching mosfet blown out, have replaced that.
But when connected to mains there's clicking (ticking) noise coming from the transformer. Then i googled it and found similar problems people having. According to those references i replaced all electrolytic capacitors and problem still persist.
I read on another forum that, this is because the board is getting its over current triggered and that is causing ticking. There it was advised to check for short on load side and then check shorted components on board. I found a resistor thats shorted and unfortunately the color code of that resistor is rubbed off and it's 8th of a watt resistor.
So how to find the unknown value of a resistor. Only black band is visible. And its the second band.
Datasheet for the ic is attached and the resistor is connected to pin1 and it is in series with 10nf cap which goes to ground.
During the initial stage of repair the board was having fuse and switching mosfet blown out, have replaced that.
But when connected to mains there's clicking (ticking) noise coming from the transformer. Then i googled it and found similar problems people having. According to those references i replaced all electrolytic capacitors and problem still persist.
I read on another forum that, this is because the board is getting its over current triggered and that is causing ticking. There it was advised to check for short on load side and then check shorted components on board. I found a resistor thats shorted and unfortunately the color code of that resistor is rubbed off and it's 8th of a watt resistor.
So how to find the unknown value of a resistor. Only black band is visible. And its the second band.
Datasheet for the ic is attached and the resistor is connected to pin1 and it is in series with 10nf cap which goes to ground.
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