Help needed on identifying a SMD part for repairing a QNAP TS-431X

[Geronimo]

Dear all,
as an enthusiastic viewer of the EEVBlog Youtube channel, it is now time for me to ask for advice.
I’m trying to fix a QNAP TS-431X which I bought cheap because it does not power on.

Following the incoming voltage from the power supply and using a Seek thermal camera, I identified a TSOP6 part (SOT23-6) which gets visibly hot and where the voltage drops down. This 6-pin part is marked “320” with a dash above the 3 and below the 0

After having some trouble to unsolder this part (still have not found yet the best solution for doing this neither by my rusty soldering iron nor the cheap reflow gun), I measured and identified the joints coming in for the power supply and some passive devices all around. The results are shown in the following drawing alá DaveCAD

Obviously, the unknown part has something to do with voltages regulation. The active part after that is an TPS22965 which is known as a Load Switch. I guess you would call this set up a buck converter but I might be wrong. Searching all around the Internet for “SMD marking 320” and similar on all known SMD code sites and papers, I have yet not found the brand/manufacturer or any SOT23-6 device which comes even close to this one.

There are three similar builds on the board which all use the “320” part so I have taken the burden to unsolder another one for measuring or maybe later swap. Maybe I can do some further analysis of the actual fault on the board with that. In the pictures below you can see the setup of the board and the particular areas where I have touched it.

Notice the rectangular areas marked red where one of the “320” is left on the board and the assumed faulty one is missing.

I’m thinking about taking the assumed bad part in comparison with the other to verify it is broken. Measuring it with my multimeter in Ohms range it clearly shows some differences whilst measuring some pins against others. I hope I’ll cause no damage with that.

My question to you all is about the actual part named “320” itself. Does anyone know this part or can help me to identify this?
Even if have done my very best to reverse engineer the schematic it might contain some failures. I doubt i.e. the value of the capacitors as the mostly show the same. However, I hope the meaning of it helps to identify the purpose of the unknown part so its character/type to search for will reveal some real part number and datasheet.

Kind regards to all, special thanks to Dave for showing me so much in his wonderfully entertaining way.
Stay healthy and always a little bit curious,
Geronimo

[Geronimo]

Here is the third picture which I could not upload before due to maximum limitations.

This shows where the working and assumed broken part was located, its neigbour the TPS22965 (in the doted area) an the remaining one.

Kind regards,
Geronimo

[coromonadalix]

the nearest thing i found is : XC6505 or an apl5301 or apl5302   ldo regulator,s  but it have 5 pins not 6 like yours, and yours with an inductance near it, must be or could be an switching regulator ?

if you search sot 23-6 switching regulator   say at mouser like this : 

https://www.mouser.com/Semiconductors/Power-Management-ICs/Voltage-Regulators-Voltage-Controllers/Switching-Voltage-Regulators/_/N-668jt?P=1z0z7v7

you'll have tons of models a whoping 7 pages to search and try to fit your "dave cad"  loll  on them ??

OR 

Google this : sot 23-6 switching regulator

And check your results in image format you may get a hit


the only thing who seems to give something  tps64202    : http://www.ti.com/lit/ds/symlink/tps64202.pdf

[MLXXXp]

Probably a TPS563200

http://www.ti.com/lit/ds/symlink/tps563200.pdf

[Geronimo]

Wow!

that was quick. Thank you both for your support. 
The search options I tried in a similar way but no luck. The TPS563200 looks very promising and has as far as I can see all pins in the right order.

Kind regards,
Geronimo

PS: If my wife lets me  , I'll give it a try tomorrow and let you know the results 

BTW: Looks like I still cant get it out when it is a SOT or TSO device. It was all so easy in the old days! 

[MLXXXp]

In case you care, the first place I search when trying to find a SMD part, based on markings, is AliExpress.
For this one I searched for:
320 sot23-6

[Geronimo]

Really good to know!

I actually rather used Google but could not find the right part even after a few days of search.
At first place I tried to identify the right package name, maybe this was my problem.
Reading through many so called SMD code books even took me further down, nothign seemed to be right at all.

Now that you show/tell me how, it looks so easy and all your hints give proper results.
I'll keep AliExpress on my favorites by now.

Once more thanks a lot for your support.

Kind regards,
Geronimo

[fzabkar]

Here is another way to search using Google:

https://www.google.com/search?q="sot23-6"+320+filetype:pdf+converter

[Geronimo]

Probably a TPS563200

http://www.ti.com/lit/ds/symlink/tps563200.pdf

Now that the electronics parts Mafia^* has delivered the spare parts in Germany, I can confirm that the unknown component "320" is the said TPS563200.
The actually defective left in the photo at position U55 (next to L38) supplies + 5V, the other with the name U53 (next to L37) supplies + 3.3V

However, the story is not over yet, the ZSA0 (U56) behind L38 gets + 5V in, but nothing comes out.
Now I have to make sure that this really damaged before I start the nightmare work for desoldering it.

^* Digikey would have only asked EUR 1.06 per each but outrageous EUR 18.50 for shipping. 
Develektro charges EUR 1,27 per each part, but also EUR 8.99 for a simple envelope shipment. Delivery however only took two days whis is okay.
I didn't want to go the cheap and dubious Chinese way, so I had no other coice.
Sounds liek I'll have to pay another shipping for the next damaged component. I'll keep you all updated how the story goes on.

Cheers,
Geronimo

[thinkfat]

Probably a TPS563200

http://www.ti.com/lit/ds/symlink/tps563200.pdf

Now that the electronics parts Mafia^* has delivered the spare parts in Germany, I can confirm that the unknown component "320" is the said TPS563200.
The actually defective left in the photo at position U55 (next to L38) supplies + 5V, the other with the name U53 (next to L37) supplies + 3.3V

However, the story is not over yet, the ZSA0 (U56) behind L38 gets + 5V in, but nothing comes out.
Now I have to make sure that this really damaged before I start the nightmare work for desoldering it.

^* Digikey would have only asked EUR 1.06 per each but outrageous EUR 18.50 for shipping. 
Develektro charges EUR 1,27 per each part, but also EUR 8.99 for a simple envelope shipment. Delivery however only took two days whis is okay.
I didn't want to go the cheap and dubious Chinese way, so I had no other coice.
Sounds liek I'll have to pay another shipping for the next damaged component. I'll keep you all updated how the story goes on.

Cheers,
Geronimo

My to-go source for most electronic components in  Europe is TME nowadays. Check their website, they charge around 6€ for DHL shipping which is quite reasonable.
Unfortunately they're no longer authorized to sell Texas Instruments parts. TI has been culling their distributors lately, noone left in Europe but RS, it seems.

Mouser and Digikey offer free shipping if your order is higher than 50€.

[Glenn]

Hi Geronimo

I would love to hear how this turned out. Where you able to fix the Device?

I've got one her aswell.

Thanks Glenn

[Geronimo]

Hi Glenn,

sorry I had no luck with this so far.
I followed the path down to some kind of bouncing signal for switching the ENABLE pin of the U56.
This bouncing signal however is delivered from the Weltrend WT61P803 marked as U28.

In my understanding this part is there for driving the LCD display and I don't get around why it should drive the power on or good signal.
I should have some more investigation on this circuitry, right now I lost my atraction but will come back to this soon.

Cheers,
Geronimo

[Geronimo]

Thanks, I will have a look next time I need to order parts, Looks promissing...

Probably a TPS563200

http://www.ti.com/lit/ds/symlink/tps563200.pdf

Now that the electronics parts Mafia^* has delivered the spare parts in Germany, I can confirm that the unknown component "320" is the said TPS563200.
The actually defective left in the photo at position U55 (next to L38) supplies + 5V, the other with the name U53 (next to L37) supplies + 3.3V

However, the story is not over yet, the ZSA0 (U56) behind L38 gets + 5V in, but nothing comes out.
Now I have to make sure that this really damaged before I start the nightmare work for desoldering it.

^* Digikey would have only asked EUR 1.06 per each but outrageous EUR 18.50 for shipping. 
Develektro charges EUR 1,27 per each part, but also EUR 8.99 for a simple envelope shipment. Delivery however only took two days whis is okay.
I didn't want to go the cheap and dubious Chinese way, so I had no other coice.
Sounds liek I'll have to pay another shipping for the next damaged component. I'll keep you all updated how the story goes on.

Cheers,
Geronimo

My to-go source for most electronic components in  Europe is TME nowadays. Check their website, they charge around 6€ for DHL shipping which is quite reasonable.
Unfortunately they're no longer authorized to sell Texas Instruments parts. TI has been culling their distributors lately, noone left in Europe but RS, it seems.

Mouser and Digikey offer free shipping if your order is higher than 50€.

[Glenn]

Hi Geronimo,

there is a nother Thread here: https://www.eevblog.com/forum/beginners/what-ic-is-this-s8920/

He is saying he had similar issues and fixed it by shorting the Vin with Vout of U54.

On my Device i can see the SR PIN oszilating between 0 an 5V and it is corresponding to a high pitched quitet beep.

Is it the same with yours?

[kripton2035]

FWIW : RS components sends free if you are an individual and order during the week end.
it is like so in France, but I suspect it is the same in the rest of europe
and they have a great catalog for these kind of ic to repair devices.
I almost order by them, it is at home generally by tuesday !
https://www.rs-particuliers.com/Default.aspx

[Geronimo]

Hi Geronimo,

there is a nother Thread here: https://www.eevblog.com/forum/beginners/what-ic-is-this-s8920/

He is saying he had similar issues and fixed it by shorting the Vin with Vout of U54.

On my Device i can see the SR PIN oszilating between 0 an 5V and it is corresponding to a high pitched quitet beep.

Is it the same with yours?

Sorry, I got lost on this repair. 
Tracing down the ENABLE signal of this IC, I ended up at a what I understand is a Video Chip. 
Now as I read this I will try to get back soon to the buried board and try this solution.

Will let you know when I get to it and maybe get it fixed.

Cheers,
Geronimo

[goncalo]

Hi Geronimo.

Have you managed to find the fault in your NAS?
I have an identical model with the same problem, and, I guess, 1/100 of your knowledge in troubleshooting this issue 

Gonçalo