Dell studio xps 1340 (DA0IM3MBAG0) hot System 5v/3v chip

[dwnisup91]

Hey
I'm a beginner trying to fix a dead dell laptop motherboard. When the power adapter and the FFC that connects the power button is connected I noticed the Sys 5v/3v chip gets extremely hot to touch. I disconnected the FFC and the Sys 5v/3v chip was still warm. The voltages of Pq43 and Pq46 are at 19v which I think is fine. PQ42 and PQ44 both show 3.1v which I think shows something is wrong. I checked the chemical capacitors PC170 and PC159 and I get 0v. I am not sure why this happened or what to do to fix the issue. Any help or advice is appreciated! Thanks

[mon2]

Re: Dell studio xps 1340 (DA0IM3MBAG0) hot System 5v/3v chip

If it hot to touch, the part may be defective or is overloaded.

Remove all power and check the resistance to ground of the output rails of this component. Check for a low resistance which means you have a shorted part.

[dwnisup91]

Re: Dell studio xps 1340 (DA0IM3MBAG0) hot System 5v/3v chip

I checked the resistance on the 5v/3v chip and got nothing on my multimeter. So the chip is shorted?

[mon2]

Re: Dell studio xps 1340 (DA0IM3MBAG0) hot System 5v/3v chip

What is the exact measurement on your multimeter? Can you share a pic of the measurement from the front face of the meter?

Is your meter auto-ranging for the resistance scales or is a manual select version?

If manual select, if the range is too low to measure, the meter face will show '1' or 'OL' for over limit. At that stage, select a higher resistance scale till the meter can offer a valid measurement.

[mcplslg123]

Re: Dell studio xps 1340 (DA0IM3MBAG0) hot System 5v/3v chip

Resistance on pin7 of PU9?

[dwnisup91]

Re: Dell studio xps 1340 (DA0IM3MBAG0) hot System 5v/3v chip

The angle is awkward but this is the resistance shows 98.3

[dwnisup91]

Re: Dell studio xps 1340 (DA0IM3MBAG0) hot System 5v/3v chip

What is the exact measurement on your multimeter? Can you share a pic of the measurement from the front face of the meter?

Is your meter auto-ranging for the resistance scales or is a manual select version?

If manual select, if the range is too low to measure, the meter face will show '1' or 'OL' for over limit. At that stage, select a higher resistance scale till the meter can offer a valid measurement.

This resistance of the 5v/3v chip is .117. This resistance kept increasing. I took a a picture when the reading slowed down.

[mon2]

Re: Dell studio xps 1340 (DA0IM3MBAG0) hot System 5v/3v chip

Based on the pic in post #6, the measurement is ~98k ohms.

Switch to the next lower scale of 20k. The meter should show '1' or 'OL' for over limit. This confirms that the measurement is > 20k ohms. No fault here.

[Sephir0th]

Re: Dell studio xps 1340 (DA0IM3MBAG0) hot System 5v/3v chip

Measure in 200 Ohms range. Everything else is simply useless and confusing at this point.

[dwnisup91]

Re: Dell studio xps 1340 (DA0IM3MBAG0) hot System 5v/3v chip

My multimeter doesn't give a reading when set to 20k or below for pin 7.

[mcplslg123]

Re: Dell studio xps 1340 (DA0IM3MBAG0) hot System 5v/3v chip

The pic in post#6 doesnt correspond to 3v/5v PWM. I think i have different schematic. Please link your schematic to avaoid confusion. I used Quanta im3(jolie) rev 3A

[dwnisup91]

Re: Dell studio xps 1340 (DA0IM3MBAG0) hot System 5v/3v chip

The schematic I was linked to on the forum was rev 1B. I have access to 3A and 1B and can use either moving forward.

https://www.badcaps.net/forum/showthread.php?t=118930

[mcplslg123]

Re: Dell studio xps 1340 (DA0IM3MBAG0) hot System 5v/3v chip

Both the version show 3v/5v regulator as PU9 and its MAX17020. Look for this chip and measure resistance on pin7. the chip may be with other name like TPS51427/PM6686/ISL6237