Power plugged upside down - smoke - HDD board chip part R744

[Jack1988]

Hi,

Just now I plugged power cable to my HDD but upside down. I don't know why. It's my mistake.

And I switched it on. Then all at once I spotted a tiny spark and tiny amount of smoke + smell. Soon I unplugged from HDD. But noticed the * on the chip unit's side.

Have not tried powering again.

I'd like to purchase and replace that part.

It reads on the chip "ON QE R744.". HDD model = SP2514N

Photo attached.

 

[FvM]

It's most likely a TVS (transient voltage supression diode) with an Onsemi branding, but no standard catalog part. The fact, that the case is apparently crashed makes me think, that the device finally disconnected the short current during the polarity reversal event. In this case, I fear that more parts are permanently damaged.

The TVS has to purpose in normal operation, so you can desolder it without replacement, if you're sure about the correct power supply. Try if the HDD is still operational. If not,there isn't much hope.

If you need to recover the data, there may be a chance to replace the controller board from a same type device.

 

[Jack1988]

Re: Power plugged upside down - smoke - HDD board chip part

Thank you so much your prompt answer. It really gave me great inspiration on HDD fixing.

I have one additional question: If fortunately it's working by taking TVS off from HDD board without replacing, does it not mean that it's OK to leave TVS there to have it work again?

The TVS has to purpose in normal operation, so you can desolder it without replacement, if you're sure about the correct power supply. Try if the HDD is still operational. If not,there isn't much hope.

 

[FvM]

If the TVS has failed by "open circuit", yes. The normal behaviour would be rather short circuit, or an undefined state in between, possibly drawing high current spontaneously. Desoldering is rather easy with two solder irons, if you don't have a suitable tool.

 

[123jack]

Re: Power plugged upside down - smoke - HDD board chip part

ahh .. I love the smell of crispy electolytics in the morning...

jack

 

[Jack1988]

SUCCESSFUL!

Hi FvM,

I tried to power on with it still stayin on the board. It made thick white smoke again.

Took it off the board and tried again. It's working now. Checked with Crystal Disk Info for S.M.A.R.T.. It's showing "GOOD". Copying files from & to the HDD is OK.

Thank you for your kind advice.

If the TVS has failed by "open circuit", yes. The normal behaviour would be rather short circuit, or an undefined state in between, possibly drawing high current spontaneously. Desoldering is rather easy with two solder irons, if you don't have a suitable tool.