laptop power IC died, help iding it, yQDQA/yQDQ4 marking, acer ph315-55 - Page 1
Forum section: electronics / repair

author: Anthocyanina
author_rank: Frequent Contributor
timestamp: December 02, 2023, 11:33:07 pm
content: hi, typing on phone, short descriptions. the computer was working fine, then after shutdown, no charging light, wouldnt turn on, battery voltage is present, charger voltage is present where it should be, no signs of life. IC found exploded as in picture, no success IDing it, any help welcome. Thank you

author: fzabkar
author_rank: Super Contributor
timestamp: December 02, 2023, 11:40:31 pm
content: I'm betting it's a Silergy part.

author: Anthocyanina
author_rank: Frequent Contributor
timestamp: December 02, 2023, 11:49:01 pm
content: thanks, looking for silergy power IC i found this:https://groups.google.com/g/datarecoverycertification/c/GOf_vB-c5o8?pli=1the picture of it shows basically the same layout as my exploded chip. how likely is it that the same chip will have different markings?thank you

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 03, 2023, 12:05:17 am
content: - wrong schematic, deleted -

author: fzabkar
author_rank: Super Contributor
timestamp: December 03, 2023, 12:22:44 am
content: Quote from: Anthocyanina on December 02, 2023, 11:49:01 pmThat thread is talking about this chip:https://www.semiee.com/file/SILERGY/SILERGY-SY8386BRHC.pdfIts marking is Qqxyz - Device code: Qq, x=year code, y=week code, z= lot number codeThe case is important. For example, yQxyz and YQxyz refer to two completely different Silergy parts:https://datasheet.lcsc.com/lcsc/2204071830_Silergy-Corp-SY7311AADC_C2986879.pdf

author: Anthocyanina
author_rank: Frequent Contributor
timestamp: December 03, 2023, 12:22:59 am
content: thank you David! that is a different model, but i will take a look and see how different that section is.

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 03, 2023, 12:24:29 am
content: Attached correct schematic now!

author: fzabkar
author_rank: Super Contributor
timestamp: December 03, 2023, 01:34:53 am
content: Quote from: DavidAlfa on December 03, 2023, 12:24:29 amLooks like different IC to me (wrong pin count):No luck here either:https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-laptops-tablets-and-mobile-devices/80630-ic-marking-codes-and-datasheets?p=1538202#post1538202

author: Anthocyanina
author_rank: Frequent Contributor
timestamp: December 03, 2023, 01:45:55 am
content: thanks David, that again isn't the right model, the chip, PUB1 is indeed the charger ic but isnt accompanied by the inductors mentioned. attaching more pictures. Thanks again!(attaching one picture, phone wont resize to a low enough size for more)in this picture, the red arrow shows the exploded ic, the yellow circle the charging circuit, and the red dot is connected to the battery's red dot with a diode, green dot to ground directly, that is what the capacitor was connected across. whe the charger is plugged in, i get 20v across what was the capacitor(it fell off when i tried to measure)so that explains the diode to battery+.the battery charging circuit is the bq 24800, and is getting the 20v from charger. i will check the pinout and see if there is any output to battery, but wuthout charging light on, i guess the charger ic isnt being enabled, maybe dependant on the blown ic.thanks!

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 03, 2023, 01:55:54 am
content: Then find the motherboard name and search it!

author: Anthocyanina
author_rank: Frequent Contributor
timestamp: December 03, 2023, 02:00:39 am
content: yes, i've been trying to find it, no luck yet. thanks! it is a hh53a la-l992p rev 1c if anyone could share the schematic or has it and can give me the part name. thank you!

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 03, 2023, 02:23:41 am
content: LA-992 r1b schematics, I don't think it's very different from r1c?The pinout of the SY8388BRHC seems identical.https://www.aliexpress.com/item/1005003630991643.html

author: Anthocyanina
author_rank: Frequent Contributor
timestamp: December 03, 2023, 02:32:09 am
content: and it is the yQ part. thanks a lot David!

author: fzabkar
author_rank: Super Contributor
timestamp: December 03, 2023, 03:18:45 am
content: FYI, I notice that the "B" part is a fixed 3V regulator whereas the "A" and "D" parts are variable, and have slight pinout differences.https://datasheet.lcsc.com/lcsc/2207201830_Silergy-Corp-SY8388ARHC_C5110279.pdfhttps://www.semiee.com/file/SILERGY/SILERGY-SY8388D3RHC.pdf

author: Anthocyanina
author_rank: Frequent Contributor
timestamp: December 11, 2023, 11:22:07 am
content: alright, tonight i'm finally able to work on this. I've removed the bridge PJ302 which makes the output of that supply available to the system, but now, between +3VALW and ground, a 1 ohm path remains. between the output of PU301 and ground, it's a direct 0 ohm short, measures 0.1 ohm on my meter(same as shorting the probes) so this 1 ohm i measure between +3VALW and ground must be from something else that died that is connected on that rail. I've gone through the schematic probing at everything on that rail that i can find by eye, but i haven't been able to find all the ICs or other components connected to it.searching by eye becomes very tedious, so, does anyone have the boardview and would be willing to share?i'm completely broke and can't afford the ~10$ repair websites charge for it. this is not a job, i'm repairing this laptop for myself. i got it from a friend for very cheap cause it has some physical damage(it's bent and has some serious dents behind the display) so it's something i really would love to be able to fix it as i can't afford another laptop, much less one like this one, so any help with the files is extremely appreciated.thank you all!

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 11, 2023, 11:40:14 am
content: Ceramic caps LOVE to short out.I've fixed a ton of expensive laptops where the culprit was a shorted 3.3Vaux cap, happened specially in Lenovo and Acer devices.Inject 3.3V limited to 1A and see what heats up, if the short is very hard then it might need a lot more current, sometimes up to 5 Amps!3.3V is basically connected to a thousand parts, you can't really diagnose a hard short even with the schematic and / or boardview, maybe with a microOhm meter, but not a common device.A typical DMM won't be able to show anything either, as the smallest step is usually 0.1Ohms.The easiest way is the current injection, if you have any small PSU at home.You could make your own with an ATX PSU, connecting the 3.3V output through 2.2R 5W power resistors.Buy two, first connect only one, so the current is limited to 1.5A.If nothing heats up, connect the second resistor in parallel for 3A.The resistors will get pretty hot, so keep them away from everything, will melt plastic parts and cause burns if not handled properly.

author: SeanB
author_rank: Super Contributor
timestamp: December 11, 2023, 12:22:47 pm
content: You can see the cooked ceramic capacitor next to the PL silkscreen on the board, 2 ceramic chip capacitors, and an inline ferrite, with the capacitor looking very smoked, and a bead of silver extruding from it. Remove and replace with a new one, probably something around 22uF 10V, not too critical as it is X7R, and likely varies wildly anyway. you can even scrape off more of that soldermask by the capacitor, avoiding the tented vias, and solder in a 22uF 16V tantalum there, and get the same performance, just with less fireworks, as there is room, and there is enough height for a tant there anyway,.

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 11, 2023, 12:34:06 pm
content: But PL311 is the input (19V), not the output.

author: SeanB
author_rank: Super Contributor
timestamp: December 11, 2023, 02:29:36 pm
content: Then use a 25V part, again with replacing a multilayer ceramic any value from 4u7 to 22uF will work there.

author: Anthocyanina
author_rank: Frequent Contributor
timestamp: December 11, 2023, 02:31:50 pm
content: thank you, i'll see if i have a supply that can source enough current to try that.about the capacitor. it fell off when i was probing last week when i first encounter the problem. i cleaned the pads today, the only new development, regarding the hardware, is seeing there is still a short on that rail. there's another development, i plugged the os drive to my desktop, booted from it, and see the shutdown happened as scheduled according to the event viewer, so whatever killed that chip and anything else that is dead happened either on shutdown or after the computer was already off. I had scheduled a shutdown(falling asleep to a netflix show) so i was asleep when the computer died, but good to know it didn't happen when the computer was still on, that could be a clue, at least going from the power sequence timing in the pdf.thanks again!(still would appreciate a boardview if anyone would like to share)edit:thinking about it a bit more, it seems whatever happened at the exploded IC's location was not the cause, but a symptom. its output doesn't have current limiting protections in place, so i think it likely that the 1 ohm short on the rail pulled too much current and caused the explosion. this does not explain the shorted cap at its input tho, nor how it could have happened at or after shutdown, hmmm!

author: Anthocyanina
author_rank: Frequent Contributor
timestamp: December 11, 2023, 02:32:57 pm
content: Quote from: SeanB on December 11, 2023, 02:29:36 pmyes, thank you, i know that will need to be replaced, but since there are still other dead parts in the board, i'll need to find them before replacing other parts

author: Anthocyanina
author_rank: Frequent Contributor
timestamp: August 01, 2024, 06:59:50 am
content: so a few months i won a proper bench power supply and have been using it for regular home lab stuff as well as to try to find the short in this board, i've current-limited it to about 500mA and have been trying to find what gets hot, and nothing, so i set the limit to 1A, and at 1A i get about 300mV at the soldered terminals on the board, but with the 3.3V bus having so many components connected to it, the short might be very far from it, and i still can't find what gets hot, maybe the ~1W that's being put through the circuit it spread too thin and nothing gets hot with that? i've been trying the alcohol method, but everywhere it evaporates equally fast, so i haven't detected the short that way, so, what would you recommend? should i try with higher currents? any tips for finding shorts? i've seen people using the flux mist method, but i don't have access to that as i'm completely broke.finding shorts in other stuff i've repaired has never been this difficult.thank you

author: perieanuo
author_rank: Frequent Contributor
timestamp: August 01, 2024, 08:02:24 am
content: usually my current limit was at least 8A to find what component is heating with back of my hand. thermal camera if you can get one will point also.of course, at that current, the shorted capacitor just burns out, but i was on time constraints. most of laptops worked without even replacing the shorted cap, eliminating him was enough.of course, try to raise current from 3A up if you wanna play.br

author: DavidAlfa
author_rank: Super Contributor
timestamp: August 01, 2024, 01:56:04 pm
content: Keep increasing the current 1A at a time, waiting at least 30 seconds before increasing again and touching here and there for something getting hot.Don't go right away to 5A or whatever, you will cause more damage to the the board if something burns out.

author: Anthocyanina
author_rank: Frequent Contributor
timestamp: December 03, 2024, 07:51:48 am
content: ok! so today i decided to pick this thing up again for more testing, and i had given up on this laptop so i just turned the current to the max, at 3v and that surprisingly was using 10w, so i start poking around with my finger and found a seemingly empty spot on the board getting uncomfortably hot after a few seconds. i turned the board around, and i don't see anything, just some tape+shielding material that i had completely ignored last time, so this time i just peeled it off a little bit not expecting to see anything there, but this is what i found. this IC by the USB ports(in the attached image (it looked physically ok)). i removed it, tested again, this time the draw was about 3w, but it was getting hot in the same area, so i completely removed the tape and found another identical IC also getting very hot. I removed that one, and the short on the 3v rail was gone.while removing the originally exploded IC, i accidentally removed some passives around it, easy enough to repopulate. But! now that i found the short on the 3v rail, i wanted to try powering up the laptop using the soldered wires that i used to find the short to get 3v up.I tried this, and nothing at all happened. no charging lights, no signs of life at all. i only supplied +3VALWP, but the exploded IC also seemed to supply +3VLP. Looking at the power sequence, +3VLP comes on when the power button is pressed, or 2.23ms after AC_IN, not clear if it's the delay that brings it on, or if it's the power button press.What would you recommend? should i also supply +3VLP with another psu?as i'm still broke, i think i would only buy the exploded IC if it was confirmed that the problem is gone, but maybe that IC itself is necessary to dtermine if the problem is gone.It's been about a year now since this died, and i've been taking a look at it every now and then, to see if i come up with something, and today has been the most productive day in finding the problem with this laptop!