Minghe B3606 - higher input voltage

[asymcon]

Hi,
I had a little accident with my B3606 today, I plugged 48VDC into its input, forgetting to look at the specs, which only list 40VDC. Almost inaudible pop later, and now I see input voltage on the output, impossible to set.
Looking over the board, nothing seems to be visibly burned. Any kind of assistance on what component might need replacing would be appreciated.

[coromonadalix]

Thread : https://www.eevblog.com/forum/reviews/b3603-dcdc-buck-converter-mini-review-and-how-the-set-key-could-be-fatal/75/

Schematic : https://www.eevblog.com/forum/reviews/b3603-dcdc-buck-converter-mini-review-and-how-the-set-key-could-be-fatal/?action=dlattach;attach=137507;image

Maybe 1 or 2 regulators have failed on the +  line

[asymcon]

Just to be sure, this is B3606 not 3603

[coromonadalix]

Sorry  i should have wrote  maybe there is some ressemblance in the input stage ??

[asymcon]

This is how the PCB looks like. D4 was obviously blown, so I replaced it. I assume you mean these two components?

[coromonadalix]

thoses are lm272 op amps

ooooooooooooh   found this:
https://github.com/UsrnameTaken/B3606

Check the docs folder you have B3606.pdf  you have the schematic,  hit the download

US1 and US2  are the main regulators circuitry, maybe one of them is kaput ? or power diodes need to be checked too ?


You have an small blog about the 3303 with some upgrades, need translation (russian).
https://mysku.ru/blog/aliexpress/33406.html

good luck

[asymcon]

D4 terminals are shorted, even if the SS14 is lifted, so my totally illiterate guess would be that XL4016 is dead because Vin = SW.
Hopefully anyone with more proficiency in reading schematic can confirm this. 

[coromonadalix]

ss14 should protect against reverse voltages

[limces00]

Hi. I did the same mistake and after that the output voltage become the same as input voltage. So by trying I discovered that the LM2596 was damaged. I replaced the LM2596 by a LM2596HVS and added a resistor before the imput of the XL1509. Now my B3603 accept till 55-60 volts input and regulate till 40 volts output.