Hi,
Finally, I put my hands on my old A6000. This model has AMD Turion CPU, Nvidia graphics with dedicated memory and SIS chipset.
Symptoms and notices:
- no video on LCD
- backlite works OK
- video OK on external monitor through 15pin VGA out
- computer boots, works OK on external monitor when LCD is disconected
- LCD is OK, tested on another laptop
- RSS090N03 MOSFET underneath SIS southbridge quickly gets very hot
- RSS090N03 MOSFET somewhere on DCDC near battery socket reads 7ohm between source and gate
- pressing chips, bending and pressing mainboard does not make a difference
- computer charges battery and works on battery OK
I have read that A6000 has major cooling problem and SIS BGA northbridge usually fails and has to be reflowed. My concern is the MOSFET underneath SIS northbridge that gets very hot after few minutes of operation. MOSFET is not shorted and it looks OK.
Should I first replace this MOSFET and than if problem persists reflow the northbridge chip? ...or maybe some short or solder ball crack underneath SIS BGA northbridge is sucking excessive current that heats up MOSFET???!
And other thing, is it normal for second MOSFET near battery socket to have 7-8ohm between source and gate when measured in circuit? Actually there are some low ohm parts near it...
Take a look at pics, zoom in to see details.
So, to reflow or not to reflow now is the question... ;-)
Cheers!
Suad
Finally, I put my hands on my old A6000. This model has AMD Turion CPU, Nvidia graphics with dedicated memory and SIS chipset.
Symptoms and notices:
- no video on LCD
- backlite works OK
- video OK on external monitor through 15pin VGA out
- computer boots, works OK on external monitor when LCD is disconected
- LCD is OK, tested on another laptop
- RSS090N03 MOSFET underneath SIS southbridge quickly gets very hot
- RSS090N03 MOSFET somewhere on DCDC near battery socket reads 7ohm between source and gate
- pressing chips, bending and pressing mainboard does not make a difference
- computer charges battery and works on battery OK
I have read that A6000 has major cooling problem and SIS BGA northbridge usually fails and has to be reflowed. My concern is the MOSFET underneath SIS northbridge that gets very hot after few minutes of operation. MOSFET is not shorted and it looks OK.
Should I first replace this MOSFET and than if problem persists reflow the northbridge chip? ...or maybe some short or solder ball crack underneath SIS BGA northbridge is sucking excessive current that heats up MOSFET???!
And other thing, is it normal for second MOSFET near battery socket to have 7-8ohm between source and gate when measured in circuit? Actually there are some low ohm parts near it...
Take a look at pics, zoom in to see details.
So, to reflow or not to reflow now is the question... ;-)
Cheers!
Suad
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