YOGA 900-13ISK NM-A411 rev 1.0 nie uruchamia się

Witam serdecznie,
laptop miał uszkodzony chiński zasilacz. Na wejściu płyty zastałem zwarcie; wymieniłem uszkodzone PQ12 (AON7405) oraz zenerkę PD7 (DFLZ5V6) i kondensator C282 150U/6.3v. Po wymianie elementów zwarcie ustąpiło ale płyta nie daje oznak życia, gdzie dalej szukać? PQ14 i PQ23 nie mają przebicia i wydają się sprawne.

Bardzo proszę o jakąś sugestię.
Pozdrawiam

Jaki prąd pobiera płyta na zasilaczu serwisowym? Są jakieś napięcia na dławikach po podłączeniu zasilacza? Podaj rezystancje do masy ze wszystkich dławików.

Jaki prąd pobiera płyta na zasilaczu serwisowym?
<0,001A

Brak napięc na dużych dławikach


Podaj rezystancje do masy ze wszystkich dławików.

PL10 572 Ohm
pl4 1,924 kOhm
mały pl8 1,836 kOhm
pl3001 59,3Ohm
pl7 2,64 kOhm
pl9 7,97 kOhm
pl3000?(nie jestem pewien) 358 Ohm

pl16 13,05 Ohm
pl25 5,68 Ohm
pl26 5,07 Ohm
pl29 4,95 Ohm
pl27 70,9 Ohm

Measure the voltages to ground on pins 1, 4, 8 of transistors PQ5, PQ6.
Measure the voltage to ground on coil PL10.

PQ5 1- 0,2V, 4-0,12V-, 5-20,1V

PQ6 1-0,18V, 4-0,03V, 5-0,20V


on coil PL10 0V

Sorry, measured again (my fault)

resistance to ground on pin 8 of transistor PQ6 is 150kOhm and slowly growing, so measure PU4?

Measure the resistance to ground on pin 8 of transistor PQ6.

If the resistance is high (in kΩ range or greater), measure the voltages to ground on pins 1, 3, 4, 5, 6, 15, 17, 18, 20, 24, 25, 28 of charger chip PU4 with connected power supply only (without battery connected).

Have you measured this voltages without battery connected?

Remeasure the voltages to ground on pins 6, 25, 25 of chip PU4 with connected power supply only (without battery).

It was measured without battery... but i mistake with upper pinout (I counted a powerpad as a pin .... should be - pin24: 0V pin25: 13,5V but never mind, see new measurements at the end) i've got a damaged input connector jp23 by "pervious technician" so i decided to solder cables. Now i've got a voltage on pl10, its 4,75V, no voltages on other coils -but pu3 and mostly pu4 is going warm...... Currently motherboard takes about 260mA on input.

Resistance to ground on colis changed:
PL10 1MOhm
pl4 rising to 85 kOhm
small pl8 112 kOhm
pl3001 40 Ohm
pl7 2,65 kOhm
pl9 53 kOhm
pl3000?(unsure marking) 266 Ohm

Going back to voltages on pu4 without battery connected after soldering jp23 :
1 - 13,35V
3- 11,82V
4- 15,2V
5- 0V
6-5,53V
15-0V
17-4,55V
18-0,4V
20-4,55V
24-5V for a half second after pwron then 0V
25-11V
28-16,75V

I am very grateful for your and others commitment.

Remeasure the voltages to ground on pins 1, 4, 8 of transistors PQ5, PQ6 with connected power supply only (without battery connected).

Battery disconnected;
PQ5: 1 -13,3V, 4 - 15,2V, 5 - 20V
PQ6: 1 - 13,3V, 4 - 15,2V, 5 - 13,32V

Measure the voltages to ground on both pins of diode PD2 and resistor PR71.

Sorry.

Again:



There is no short. It was caused by power supply when its disconnected. Now its 178kOhm to ground from this point.
Resistor is ok, 10 Ohm. Capacitor pc103 also (measured 1,08uF).

Check your measurements again.

EDIT1:
The resistor PR71 (10Ω) is probably bad. Check it.

EDIT2:
If the resistor PR71 is okay, replace the charger chip PU4 (BQ24770).

Is there something what i could check with desoldered pu4 before i will have a new one?

sitoslaw napisał(a):Is there something what i could check with desoldered pu4 before i will have a new one?

If you want, you can remove the chip PU4 and transistor PQ5 from the board and check, if there is 19V on pad 28 on the place of this chip. If so, solder a new chip and solder back the PQ5.

It is important to remove the PQ5 from the board during the measurement to prevent possible additional damage on the board without charger chip.

Hi, thank You very much; PU4 replaced, its much better but there is something more- current is about 120mA and i can't see anything hot. I've got 9V on PL10. Here are new measurements after PU4 replaced:

1 ACN- 20V
3 CMSRC- 20V
4 ACDRV- 26V
5 ACOK - 0V
6 ACDET - 15,2
15 BATPRES- 0V
17 BAT- 7,1V
18 BATDRV - 9V
20 SRP - 9V
24 REGN - 5,38V
25 BTST - 14,27V
28 VCC - 19,7v

ACOK should be high when:
- ACDET is above 2.4 V (I've got it)
and
- VCC is above UVLO but below ACOV and VCC above BAT).
What is UVLO and ACOV?

From datasheet of bq24773 i know that UVLO is "under voltage lockout comparator" and voltage should be beetween 2,3-2,7V and ACOV is propably "input overvoltage comparator"?

What could i check now?

sitoslaw napisał(a):From datasheet of bq24773 i know that UVLO is "under voltage lockout comparator" and voltage should be beetween 2,3-2,7V and ACOV is propably "input overvoltage comparator"?

Yes, this chip "measure" the input voltage and shuts down, if the input voltage is too low, or too high. There are two comparators inside the chip to detect input under voltage (UVLO) or over voltage (ACOV).

Measure the voltages to ground on coils PL4, PL10.

I measured it yesterday - no changes with resistances ; PL10 -9V, PL4 if I remember 0V (i will double check afternoon).

6 ACDET - 15,2

Correct value 2.70V.
Check PR57=68k.