Compaq CQ62 power problem

[savo.lekic]

Hi guys,
have problems with compaq cq62. Laptop sometimes starts, works fine for some time and start switching between AC and battery. AC adaptor is ok, checked voltages, so are adaptor connector going on motherboard. When working normally all voltages readings are fine (checked only few components following DCIN).

After some time LED signal (ACLED on image 1 in attachments) on connector stops shining and I hear component on motherboard clicking, as it appears to me it is coming from inductor PL7 (1R0). Also voltages which are in normal mode stable start to changle in clicking rithm. Anyone had similar problem?

Voltages reading in working mode:
DCIN = 19.48V
PQ37 Drain = 19.15V
PQ36 pin 4 = 9.59V
PQ55 Gate = 19.28V

when stops working all voltages except DCIN starts changing abnormally (for example PQ37 Drain changing between 5-19V).


Please give me some advice what to do? I can upload full schematics if needed and measure voltages in points you tell me. Also can record sound if that could shorten diagnosis.




Regards!

[naeemshahzad]

Re: Compaq CQ62 power problem

first of all cq62 have three types of motherboards you asking for which one ?
post here motherboard model number.

[JaroTech]

Re: Compaq CQ62 power problem

Hi, I think this is the schematics you need.

[savo.lekic]

Re: Compaq CQ62 power problem

Laptop model is CQ62-a20sm with AMD Athlon II P320 processor. Foxconn Motherboard, P/N: 01013TM00-575-G

I think schematics @JaroTech posted are right for this board?

[savo.lekic]

Re: Compaq CQ62 power problem

Also AC_OFF signal is 0V in working mode, and when component starts making noise it changes between 0-3V.

[savo.lekic]

Re: Compaq CQ62 power problem

Anyone have idea what could cause problem?

[khaahk]

Re: Compaq CQ62 power problem

With battery or without? Work from only battery the same behaviour? Charging battery ok without computer turned on?

[savo.lekic]

Re: Compaq CQ62 power problem

With only battery it is not making clicking sound, and can be used normally. Also it is charging batery. in windows for long time it is saying that is not charging becouse battery is bad, but orange LED is on next to AC plug. One more thing, PC must not be on to make that clicking sound, so it must be something in charging circuit gone bad.

PC works ok with battery, but board is doing same thing "pluging" in and out AC adaptor. When I plug battery in one capacitor is making noise and voltage on PCE20 is varying between 19.18V and 19.26V in loop while making noise. Not shure if noise is coming from this capacitor. When battery is out there is no noise, but just clicking sound after some time.


When it is making "click" noise there is no +5V on PCE18 (page 32.). Maye that can be usefull, as I think some component on page 31. is bad...

[Djosla]

Re: Compaq CQ62 power problem

You hear clicking of inductors most likely due to mosfet leaking...
When you pull out the battery,so that the laptop is only on adapter ,do you hear clicking...?
What are voltages in non working mode on :
+VBAT rail
ACIN,ACOK on MAX8731 ic
PQ55 drain
PQ38 gate

Acin needs to be low in order to have acok high to drive that transistor...Something could be wrong with internal comparator...
8731 is most likely culprit here,if you have it try to change it...if doesn`twork after replacement we will help you to diagnose it further...

A dje si Savo

[savo.lekic]

Re: Compaq CQ62 power problem

Ok. I will measure all voltages later and post it here.


Hahaa, a dje si ti Djosla!!!