Boost ZK 4KX low output damaged?

[marce002]

Hi
This device is a common buck boost 0v to 30v...
It was working good now shows close to 0V output whatever Volt I set. The unit is powered from good amps 12v server power supply. I took appart and shows no phisical damage... mosfet looks fine ..what can i try? see pics:

thks in advance!!

[marce002]

Changed the mosfet, and problem still there. sad

[truclacicr]

Check FP5139. Is it being turned on (BR/CTL)? Does it have a Vcc supply?

https://www.insidegadgets.com/wp-con.../07/FP5139.pdf

[marce002]

thks ... it seems low v ..(tested with output enabled 5v 3A , display showing 0.67v 2.92A no load!!) and in 5139: 0.369v in vcc pin and 0.249v in br/ctl... will check who gives vcc to ir right?

[marce002]

nope, the source power is from 7550 regulator and his output to the FP5139 is exactly 5V, so the problem is in the "load side", what else can I test...? or maybe fp5139cis fried?. thks again!

[truclacicr]

If BR/CTL is low, then the FP5139 is switched off (disabled).

[marce002]

As i stated before i have 0.249v in br/ctl... so maybe should desolder it and test if shorted ?
Now i realize that seems to be D8 shorted.