Dell Inspiron 15 33308 Fried M/B

[orestes_]

Hello,

I have the motherboard of a dead Inspiron 15. I (think) I have narrowed it down to the root cause of the problem: there is a fried buck converter on the M/B (51225 by TI). I found this specific IC gets very very hot when plugged in.

Will replacing this IC solve the problem or is there something else causing it to overheat and possibly damage it as well? Can you help me point me to towards the right direction here?

Motherboard schematic can be found here:

https://w************************3mc.html

Additional images:

https://imgur.com/a/Q7FQeTz

Thanks!

[ruletero]

Re: Dell Inspiron 15 33308 Fried M/B

First you should to check resistence to ground in 3 / alw coils, also in 3/5 ldo pins of the IC (51225), maybe you have a short.

[mcplslg123]

Re: Dell Inspiron 15 33308 Fried M/B

@ruletero has nicely guided you. Remove the IC(Dont apply power to mb in this condition),clean the pads and then measure resistance on VREG3/VREG5 pins commonly known as LDO.You are likely to have a short on one of these LDO's

[orestes_]

Re: Dell Inspiron 15 33308 Fried M/B

First you should to check resistence to ground in 3 / alw coils, also in 3/5 ldo pins of the IC (51225), maybe you have a short.

@ruletero has nicely guided you. Remove the IC(Dont apply power to mb in this condition),clean the pads and then measure resistance on VREG3/VREG5 pins commonly known as LDO.You are likely to have a short on one of these LDO's

Hello, thank you for your replies.

I have two questions I was hoping you could help me with, I hope they aren't too oblivious.

1. Is it possible to desolder the IC with a rather large heat gun? (I do not own a hot air station unfortunately).

2. How can I tell which pin is which underneath this chip?

[mcplslg123]

Re: Dell Inspiron 15 33308 Fried M/B

There is a dot on the ic or some arrow sort of marking on the mb which denotes pin1. You have to count serially after that. If you can post a pic of your hot gun, then i can comment whether it is suitable or not. Remember, proper tools is a must for repair.

[Sametbey]

Re: Dell Inspiron 15 33308 Fried M/B

You should count clockwise from the point in the picture. Check voltage outputs 3 and 13 pins LDO, 8 and 18 pins ALWS.

[SMDFlea]

Re: Dell Inspiron 15 33308 Fried M/B

You should count clockwise from the point in the picture. Check voltage outputs 3 and 13 pins LDO, 8 and 18 pins ALWS.

Anti-clockwise

https://cdn.badcaps-static.com/pdfs/...ab1aa9ff70.pdf

[orestes_]

Re: Dell Inspiron 15 33308 Fried M/B

There is a dot on the ic or some arrow sort of marking on the mb which denotes pin1. You have to count serially after that. If you can post a pic of your hot gun, then i can comment whether it is suitable or not. Remember, proper tools is a must for repair.

Looks something like this and it has 2 settings for low airflow/heat and high airflow/heat.

I know that a hot air station would be ideal, but this is one of the very few times I had to work on SMD components, usually my T12 soldering station suffices for most of the repair work I need to do.

[SMDFlea]

Re: Dell Inspiron 15 33308 Fried M/B

You`ll burn through the board,the work bench,through your leg and the carpet with one of those, its not the ideal tool.

[mcplslg123]

Re: Dell Inspiron 15 33308 Fried M/B

Looks something like this and it has 2 settings for low airflow/heat and high airflow/heat.

I know that a hot air station would be ideal, but this is one of the very few times I had to work on SMD components, usually my T12 soldering station suffices for most of the repair work I need to do.

A clear No No with this tool.

[orestes_]

Re: Dell Inspiron 15 33308 Fried M/B

You`ll burn through the board,the work bench,through your leg and the carpet with one of those, its not the ideal tool.

A clear No No with this tool.

Yeah I thought so as well. Guess it will have to wait for now