broken caps - Samsung Galaxy Tab 4 10.1 - SM-T533 - almost fixed

[embedded_bert]

Hi, i got a broken SM-T533.. the repair company claims it to be water damage - i'd like to hear your opinions.



Obvously the caps are damaged and a first resistance measurement has shown ~8 Ohm (little low for a cap).. so i guess these are broken or the ugly stuff around is conductive!?

Unfortunately i could not find any service manual (from a site where i could actually download it) in order to find out some more about the the schematic of this board.
I guess they are only bulk capacitors, but i am not sure yet... i would be happy if someone could help me out with a service manual or a little knowledge... thank you!

[KhronX]

Have you considered cleaning that stuff off? Isopropyl alcohol and a toothbrush are great for that. Do remove the battery connector first, though.

See if you can find anything about the T530 (differences from T533 should be minor).

Actually, remove the whole mainboard and see whether you can see signs of liquid damage anywhere else. Does the battery still have any charge left in it?

[embedded_bert]

yes, i did consider that.. and i may report that i found a manual for T530 and T531.. unfortunately not for the T533.. but i already noticed that the designes differ...

i detached the battery, removed the board and looked for some other signs that would indicate that liquid came into the device - nothing at all!

after cleaning it with some IPA and a toothbrush i made some additional pictures with my simple USB microscope (sorry for de poor quality).


the gunk is very resistive..


i think i found a crack -  do you agree? does the part looks like it blew up??

the battery is flat.. no voltage at all.

[KhronX]

Yes, that end-cap in the first photo does indeed look a bit corroded, but if that's cleaned off, it should still be fine. There still seems to be some gunk between those two capacitors, though.

Last photo - reflow that solder joint, no big deal. And if that resistor (yes, that's a resistor, not a capacitor) WERE to have reasons to blow, i'm pretty sure that tiny trace coming off that "suspicious" end would've vaporized long before the resistor got toasted.

But if that tablet "took a bath", your problem's definitely not in that area.

One first step would be to switch your multimeter to diode-test mode, red probe on ground, black probe on the positive contacts of the battery connector on the mainboard. Normally that should be 0.6v or thereabouts.

If that's the reading you get, plug the battery back in, and a USB cable into the tablet, and probe the voltage between the red and black wires of the battery.

If nothing happens, you might need to "wake up" the battery externally, with a dedicated charger. Just look for "TP4056" on eBay (local to you, if possible), there should be plenty of those little blue charger boards for just a couple bucks.

[embedded_bert]

first of all i want to thank you for your support.. it's my first tablet repair project.

gunk is cleaned of.. but the resistance is still a little low between the two testpoints.. i called them A and B. diode test did only beep on each polarity.
the diode test has shown 0.0V in any direction as i connected the poitive lead to one metal-can of the motherboard and probed positive battery contacts.

i made some measurements and i was reading 300pF but no resistance on this cap/resistor-part. thats why i called it a cap. (see img below)

i will remove the the big coroded caps and resoldering the joint at the unknown (manual would be really interesting at this point) part and repeat the diode test.
thx for the tip. i already thought about the fact that this battery is only disabled by the BMS.. i will inform myself on how to heal the battery and order a TP4056 on aliexpress..

PS: my testleads add a little error to the measurement in ohms mode but i consider it to be unimportant.

[Nusa]

The first photo in the original post makes me think that can on the right might need to be removed to check for more liquid damage.

In the last photo above, it looks like the connector legs have broken loose from their solder pads. Or is that an illusion?

[embedded_bert]

i tried to remove the cap(s) but i had no success with my soldering irons since i could not transfer heat to the coroded cap pin properly.
I will go for the hot air.. but i have to prepare the board first with capton.. and prepare the working area.

I could see the smoke marks on the can too... but i guess it's the cause is outside the can... maybe only the cap on the right side of my first picture is broken.
the connector pins are okay.. i measured the contacts going to the same nets.. they are still low resitance paths -> pins still okay.

i tried a first jumpstart for the battery.. (with the DMM in diode mode) now it contains some voltage.

updates follow later...

[embedded_bert]

done.. the cap is gone!

the diode test looks good now. measured ~0,6V and the testpoints have a high resistance.

what would you recommend as a replacement? i thought 22µF/10V - like in the T530... or leave it as it is now?

there is still some flux around/under the second cap... the removed one has ~2 Ohm!

[KhronX]

If i had suitable spares at hand, i think i'd replace both. And yes, same as the T530 should be fine, it's essentially the same device anyway.

[embedded_bert]

I may report that a first test without the faulty cap was a success already - the tablet charged! 

I am going to order some 22µF/10V to replace the old ones.

But the second one has to be removed before.. and the first one was not easy already. I was wondering if they are glued to the PCB or if I maybe had a heat issue.
First I tried the iron with a blade tip (to heat both ends of the cap at the same time) without success. Then I changed to the hotair (280°C - 300°C).
It took quite a while till i could see melted solder and it did not felt like the part come off easy as usual (with the hot air).

[KhronX]

Have you tried adding some blobs of leaded solder onto the ends of the cap, first?

With a nice wide wedge-tip, it takes me 5-7 seconds to remove 1206 caps (with my iron set for 280C); those look like 0805's there.

But the second one has to be removed before.. and the first one was not easy already. I was wondering if they are glued to the PCB or if I maybe had a heat issue.
First I tried the iron with a blade tip (to heat both ends of the cap at the same time) without success. Then I changed to the hotair (280°C - 300°C).
It took quite a while till i could see melted solder and it did not felt like the part come off easy as usual (with the hot air).

[embedded_bert]

yes, i tried.. but maybe not enoug.. and since the cap was so corroded it did not stick well... i will try to add mor on the second one and use an other soldering-tip too.

only 280°C ? sonds quite low to me for solderig iron... i am working at 360°C today.. used to work at 450°C in former times. why so low? - are the pads so sensitive?

I think you are right.. X5R-G0805 22/16 fits quite well to the dimensions of the orig. (2x1,2x1mm). little more voltage should be fine i think.

[KhronX]

I seriously doubt my previous iron (an Atten knock-off of the venerable Hakko 936) would work that well, but this Ersa iCon Nano i've been using for the past few years is worth every penny of the 300-something euros it cost me  280C on this works at least as well (if not better) than the Atten set to 350 

And sure, there's no harm in upping the voltage for a filter cap. It'll never have more than 4.3V applied across it anyway, so it's all good.

[embedded_bert]

At home i was using an unregulated ERSA MultiTip 35W.. no idea about the temp of this. But invested into a propper soldering station last year. The decission took me quite a while. I went for a genuine Hakko FX-951 and i did not regret it yet. I also really like the FM-2032 microsoldering iron for this station. 

450°C was my standard setup at electronics school and later at work for ERSA or Wella soldering stations - well known good quality brands - which does not mean i could not have used them wrong...     i think i have to admit that i still have to learn a lot on soldering

anyway.. i will give the T15 D2.4 a try at 280°C..

thanks a lot for your help! 

[embedded_bert]

280°C.. wasn't working well.. so i went for 360°C again.. and the part popped of like it was glued. but it's gone and the pads are okay still.