Presario CQ71 not powering

HpPresarioCQ71 OP6

-first problem was viewtopic.php?f=213&t=28302
-laptop is dead.
-it can not be powered on.
-no any signal or light.Only white led on charging connector when charger is pluged in.
-charger ok 19.5V and id 18.8V
-if charger pluged in id drop to 0.4V
-quick messured resistance,no shortcut ,only on PQ26,C849 and PC161 have arround 25ohm

regarding part of schematic that i find and my knowledge:
-on +VA 19.5V
-on +VAD 19.5V
-on +VH28 28V
-on PQ48 4pin - 19.5 V
3pin - 2.3 V
1pin - 3.6 V

any suggestion is welcome

Hi,
First program Bios.

Hi, AD_ID must be about 1.4V, measure the resistance to ground at n.64 KBC.

daniel508
I suppose I should programing it with externa programator ?

iras72
I´m not shure what is n.64 KBC

Measure the voltage on both sides of R272.

Misurale the voltages on pins 1, 2, 3, 8, 23, 24 of PU5
voltages on all pins of PQ9

It looks like resistor R272 is burned.
I desolder it to measure resistance.It has 260 ohm.
Don´t know is that correct value (no schematic).
Measured resistance to GND:
-left side of R272 to gnd - no resistance
-right side of R272 (goes to D14) to gnd - 24 Kohm

as I find that resistor is burned I did not try to power it.
I like to do it when resistor is replaced if necessary.

Correct voltage is 1.4V at R272.
Measure the voltage on pin.3 DC-IN CONN

Power supply is original?

Should R272 be 260 ohm ? I remove them since it looks like it is burned it has hole.
I remove resistor.
Without resistor - pin3 on dc-in is 18.8 V
left side of resistor place to gnd is 18.8V
right side of resistor place to gnd is 0V
measured without resistor (resistor removed from board).
when resistor was on board AD_ID drop from 18.8 to 0.4 when insert charger
orginal power supplay (have two chargers) both work good on presario cq56

R272 must be 100Ω

ok

-r272 replaced.
-AD_ID now again 0.4V on both side of r272 (also on pin.3 DC-IN CONN)
-on showed picture I try to measure +3VPCU , I do not have 3V

Machine,since I replaced r272
measured:
PU5
1- 5V
2- 2.1V
3- 1.2V
8- 2.4V
23- 0V
24- 18.2V

PQ9
1- 0V gnd
2- 0V
3- 2V

on +VIN 0.96V
on PQ48
pin4-19.5V
pin3-0.96V
pin1-2V

Measure the resistance to gnd on pins 1, 3 PQ48
voltages on all pins of FP3
voltages on all pins PD2
Check whether short or failure PC23

-resistance PQ48
pin1- start and rasing to 160K
pin3- start and rasing very slowly to 330K

-PD2
theres no diode PD2 , only PR1.
No any voltrage on PR1 ( D/C# ).I check connection to U20 pin72.It is OK.
on PQ3 pin3 ACOK_IN have 2V

-PC23
replaced ,checked, same measuring

-FP3
dont know what is , please direct me

Zmierz rezystancję na C525 (n.64 KBC), jeśli będzie 0Ω to KBC do wymiany, lub sam kondensator C525 może być zwarty. Jeśli był spalony R272 to prawdopodobnie było zwarcie w zasilaczu pomiędzy AD_ID i 19V, powiniem je rozdzielać rezystor 330kom.

Measure the resistance of the C525 (n.64 KBC), if it 0Ω KBC for exchange, or the same capacitor C525 may be closed. If it was burnt R272 was probably a short circuit in the power supply between AD_ID and 19V, should preferably be separated by a resistor 330kom.

-on showed picture I try to measure +3VPCU , I do not have 3V

If you don`t have +3VPCU, then current across R272, goes to gnd trough D14.
So it is normal 0.4v at R272.

ricardo napisał(a):

-on showed picture I try to measure +3VPCU , I do not have 3V

If you don`t have +3VPCU, then current across R272, goes to gnd trough D14.
So it is normal 0.4v at R272.

Dokładnie tak, pod warunkiem że +3VPCU jest zwarty do masy, mam 2 sprawne takie płyty i rezystancja na +3VPCU jest około 100KΩ jeżeli nie pracują przetwornice 3/5V. Warunkiem uruchomienia klucza PQ48 jest 1.4V na AD_ID.
Zmierz rezystancję do masy PL8, PL9, PL12, PL11, PL5, PL6, PL10.

That's right, provided that three +3VPCU is shorted to ground, I have two smooth the board (OP6) and resistance to three +3VPCU is about 100KΩ if 3/5V converters do not work. Key condition for the PQ48 is 1.4V to AD_ID.
Measure the resistance to gnd PL8, PL9, PL12, PL11, PL5, PL6, PL10.

Measure the voltage on both sides of PR177
sorry "voltages on all pins of FP3" mean FQ3 (notified measure)

Since I didnt get charger with it,I was also think that is posible that AD_ID was
connected (wire shorted on charger) to 19V since R272 burned...
I will ask stupid if AD_IN was 19V so AD_TYPE also get 19V trought R272.Will this damage U20.
C525 Was checked No short on C525 resistance is 25K.

+3VPCU resistance to gnd start at 5K and slowly rise to arround 60K

PL5- 30 Ohm
PL6- 30 Ohm
PL8- 530 Ohm
PL9- 18 K
PL10- can not find on board
PL11- 1.5 K
PL12- 22 Ohm

PR177- 28V and 2V on other side pin1PQ48
FQ3 sorry I cant find that part also on schm.

Jesteś pewien rezystancji na PL8 (+5VPCU)? Musi być porównywalna z PL9 (+3VPCU) 10KΩ-100KΩ.
Jeśli tak, to będziemy szukać usterki w linii +5V.


Are you sure resistance PL8 (+5VPCU)? Must be comparable with PL9 (+3VPCU) 10KΩ-100KΩ.
If so, then we will look for the defect in the +5V line.

Checked again , resistance 530 Ohm.