Troubleshooting/ Repairing a Dead HP G6000 Motherboard

Things that are likely to be diagnosed :

• Bad capacitors. Most common issue of a dead motherboard.

• Most of the IC’s on board having 4-20 pin, such as the power distribution IC as it fails on shorting cases and are swappable easily.

• Blown fuses. Easy to diagnose easy to replace.

• Damaged jacks. Power and audio being the most commonly broken.

• Resistors. Easy to find easy to replace.

• Mosfets and diodes can be more problematic to diagnose and to fix for a beginner but they are swappable too with just a soldering iron.

• CPU Issues – Obviously you can swap CPU too so you should be able to diagnose that as well.

Likely Cause Scenario –

Machine: HP G6000 ( Same motherboard as DV6000, Compaq Presario F500, F700,F750 )

Issue: Laptop is not powering – Completely dead

Description: The machine has been water logged. It does not have step down power, which are 3V and 5V.

Let’s Diagnose The Fault: Refer Schematics if you feel any issues while checking voltages

Check Max8724 (the battery charging chip) first, because to make step down voltage this chip must work properly. This is a 28 pin chip, we only need to test 1, 2, 4, 8, 10, 11 pin. They are VIN (main power for chip), LDO (provide 3.3V for chip itself in order to set REF voltage, also provide signal to drive 2 MOS to charge battery), REF (set reference voltage of the chip), SHDN# (enable/disable chip, a switch), ACIN (indicate the power supply has plugged in), ACOK# (power adapter Ok sign with Motherboard).

Everything is OK except 10 pin, ACIN is 0V. This is incorrect as per this IC voltage regulation for this board, so the issues is Motherboard doesn’t detect there is an adapter plugged in ! Trace it backward and find it is very simple? Motherboard use 2 resistors to pull the input voltage (19V, directly from dc socket) down to about 4V, so test the first resistor and find it opened. Change it and 3V/5V power will come up and Motherboard be able to switch on.

Then the trouble starts when I try to charge the battery. The charging current never goes beyond 0.15A and after 10 seconds the charging light starts  flashing. Also can’t switch on from battery. First, change Max8724, still same problem. Next check all the resistors around max8https://acmatech.com/blog/wp-admin/post-new.php724 and change it if it has any sign of watering, still no good. Then change KB3926 (EC/KBC, chip monitors the statue of battery), still same.

Decide to check MBDATA and MBCLCK, 2 signals that send battery information from battery to KB3926 before I give up. I find the MBDATA is short!

Finally, find there are 2 pins stick together on CN10 (the connector of multimedia switch board). Fix it and it will start charging battery. Switch on with power adapter– OK sign, Remove the power adapter once switch on, battery keep the Motherboard running, OK sign. But still can’t switch on from battery once remove the power adapter. Think, think, do I miss something here or there? Oh, the CMOS battery not installed, put the CMOS battery back and everything work perfectly. The battery part of troubleshooting will takes your 1 hour max after reading this post.

Note :- System may not run if you don’t have CMOS battery or the CMOS battery is low for some AMD CPU Motherboard.

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Laptop Dead /Water Logged /Not Charging Solution