Martwy DELL Inspiron 15 7577, płyta CKA50/CKF50 LA-E991P Rev.1

Proszę o pomoc z naprawą laptopa DELL Inspiron 15 7577, płyta CKA50/CKF50 LA-E991P Rev.1

Po podłączeniu zasilacza brak jakiejkolwiek reakcji.

Rezystancja na cewkach 3v i 5v jest bardzo niska, odpowiednio:

PL302 - 1.4Ω
PL303 - 4.4Ω



Napiecia z chargera BQ24780S (PU700):

1 - 19,9
2 - 19,9
3 - 19,5
5 - 2.85
6 - 2,63
9 - 0,9
14 - 3,3
25 -5,7
28 - 19,6

Napięcia z przetwornicy 3v 5v (PU300) oznaczenie 1285B (TPS51285B?)

3 - 3,31
6 - 3,08
9 - 1,2
12 - 19,9
17 - 2,4
20 - 3,07

Pin 13 ma zwarcie do masy ( kondensator nie jest zwarty).

przetwornica grzeje sie.

Zwarcie na mosfetach PQ304 i PQ302.

Zdjąłem przetwornicę i oba mosfety ale nie zmieniło to niskiej rezystancji na PL302 i PL303. Mosfety ok., zwarcie zostało na padach na płycie. Jedyna zmiana to pad 13 przetwornicy nie jest już zwarty do masy. Zwarcie do masy wystepuje na padach: 8, 14, 18.



Rozlutowałem zwory przy cewkach i zwarcie na nich ustąpiło.



Podałem na jedną stronę zworek odpowiednio:

3.3v - jedyny element który sie grzeje to most UH2 (INTEL GL82HM175 SR30W) przy czym napiecie spadło do 1.2V i pobór prądu był 5A (max zasilacza). Most nie grzał sie jakoś super mocno ok 60 stopni.

5v - mocno grzeje sie uklad UM3 - Winbond i załączyły sie wiatraki.

Brak schematu, doświadczenia i brak pomysłów co dalej... Proszę o pomoc w dalszej diagnozie.

tb777 ha scritto:3.3v - jedyny element który sie grzeje to most UH2 (INTEL GL82HM175 SR30W) przy czym napiecie spadło do 1.2V i pobór prądu był 5A (max zasilacza). Most nie grzał sie jakoś super mocno ok 60 stopni.

Hello!
The PCH chip is damaged for sure and needs to be replaced.
If you decide to replace it, first remove the old one from the board and check, if the short circuit on 3V power rail is disappeared.

tb777 ha scritto:5v - mocno grzeje sie uklad UM3

Which chip is UM3?
This chip is probably also damaged.

matic ha scritto:Which chip is UM3?

It's WINBOND 25X20CL.

Is it BIOS chip or what? I thought UT2 (WINBOND 25Q80DV) is BIOS chip.

tb777 ha scritto:It's WINBOND 25X20CL.

I'm not 100% sure, but it may be a "Thunderbolt" controller memory chip.
This chip is supplied from 3.3V power rail, which is probably generated from 5V by the LDO regulator inside the U4 chip.

Chips U4 and UM3 are probably also damaged.

Remove the chip UM3 from the board and repeat the short circuit test on 5V coil. Check, if the chip U4 is hot.

matic ha scritto: Check, if the chip U4 is hot

Do you mean UT4 (tps65982da) located above UM3?

tb777 ha scritto:

matic ha scritto: Check, if the chip U4 is hot

Do you mean UT4 (tps65982da) located above UM3?

Yes, exactly.

UT4 is not getting hot - its USB C controller
UT1 is hot - this is Thunderbolt controller

tb777 ha scritto:UT1 is hot - this is Thunderbolt controller

UT1 is also bad. Remove it from the board and remeasure the resistance to ground on 5V coil.

Also measure the resistance to ground on pin 8 on the place of chip UM3 (chip removed from the board).

UM3 pin 8 - 2.28kΩ
This is with UT1 still on the board.

Ok, chip UT4 may survived.

Now you need to remove all damaged chips (PCH, UT1) from the board and check the resistance to ground on 3V and 5V power rails to check, if there is even more damage.

matic ha scritto:Ok, chip UT4 may survived.

Now you need to remove all damaged chips (PCH, UT1) from the board and check the resistance to ground on 3V and 5V power rails to check, if there is even more damage.

Removed PCH & UT1 and unfortunately, there is more damage in 5v line. 3V back to normal I think - resistance now 7.6kΩ.

In 5v line still 4.4Ω, power consumption is 1.3A and getting hot more components:

US1 (marking 544cv g7009 bra) - don't know what's that?
UR1 (Realtek 5176e)
UL1 (Realtek 8111h)
U13 (Parade 8713b)



Should I take all of them off the board as well? or just one making this short?

tb777 ha scritto:Should I take all of them off the board as well? or just one making this short?

If all of this chips are warm, all are damaged.
Remove them from the board and check the resistance to ground on 5V power rail again.

tb777 ha scritto:US1 (marking 544cv g7009 bra) - don't know what's that?

This chip is probably an USB power share chip.
I don't know, which exactly is according to this markings, but it should be very similar to SLG55448V or TPS2546R.

I removed all 4 from the board. Now the short is gone but still very low resistance to the ground on 5v rail- 53Ω. There is nothing really left getting hot. I found only two guys barely warm, around 30deg. It's UZ15 & UZ9 (both marked 1334 - don't know what they are? ). Power consumption on 5v line is now 0.18A so maybe these guys are just switched on and working fine?



Resuming, to make this board working I need at least:

TPS51285B - 3v 5v power supply
UH2 (INTEL GL82HM175 SR30W) - PCH
UT1 (Intel JHL6340) - Thunderbolt controller
US1 (marking 544cv)
UL1 (Realtek 8111h)
UR1 (Realtek 5176e)
U13 (Parade 8713b)
and eventually,
UZ15 & UZ9 whatever it is.

tb777 ha scritto:I found only two guys barely warm, around 30deg. It's UZ15 & UZ9 (both marked 1334 - don't know what they are? ).

Try to remove this two chips from the board and check the resistance again.
I don't know which chips are this. They may be a load power switches, similar to APE8937.

It will be difficult to repair the board with so many damaged components.
It is possible that all chips connected to 5V power rail are damaged, even if there is no low resistance on them.

matic ha scritto:It will be difficult to repair the board with so many damaged components.
It is possible that all chips connected to 5V power rail are damaged, even if there is no low resistance on them.

I have decided not to proceed further as damage to this board is extensive and that not all components are easy to find it might be costly & difficult.
Thank you matic for your assistance.