Dell Inspiron 5150 Laptop

[MEB]

Re: Dell Inspiron 5150 Laptop

I found U16 and at the start of the evening, I indeed had 3.3V on 10, 31 and 30.

I then tried to find some signals on the requested pins with a scope and was unable to find anything. I went back and have lost the 3.3V to U16. So I guess now I will attempt to restore the 3V which I evidently destroyed. I knew the scope probe was too big for those pins, but I guess I learned a valuable lesson although at this particular moment, I don't know exactly what that is.

[samanthban]

Re: Dell Inspiron 5150 Laptop

check pl 11 if 3.3 v not present then more difficult .

[MEB]

Re: Dell Inspiron 5150 Laptop

Thanks for your help. I found PL11, and although I have no idea what that device is, I am sorry to say that there is no 3V present on either side of it or
PR101 who is nearby. With power removed there is .4 ohms measured across the device PL11 in circuit.

[samanthban]

Re: Dell Inspiron 5150 Laptop

This section is called as power section 4 fet and one power Ic will be there. I think one of them or near by capacitor or resistor is bad.

[clearchris]

Re: Dell Inspiron 5150 Laptop

Ok folks, I have some red meat for you.

Cracked solder joints on power connector:


Blown up diode(?)


Flux left from previous repair?


Melted zener diode?


Well, I have many obvious clues to go on here. Maybe this can give you some clues about your board too.

[MEB]

Re: Dell Inspiron 5150 Laptop

clearchris - My board doesn't look like that, but if I continue on in my usual fashion, it just might!

samanthban - Thanks for all your direction. I am pretty slow at troubleshooting because I know very little. I stared at the schematic and the board and thought about what you said. About 3 hours later, I removed PL10 to see what B+ would do. It shot right up to 19.52V. So that tells me, what you already knew. Something is pulling the voltage down. Now I just need to find out what. I'll be back when I find something.

[clearchris]

Re: Dell Inspiron 5150 Laptop

Lol. I think this is the third board too. One was replaced under extended warranty, and another was replaced under the classaction extended extended warranty. Refurbs obviously.

Just for funsies, who needs caps?



I may replace them before this is over...

[MEB]

Re: Dell Inspiron 5150 Laptop

OK continuing on. As stated I removed PL10 and was getting 19.5 VDC at that point. With it out the problem part of the circuit is eliminated so I get higher voltage. With it in the voltage drops to around 3 VDC. So I assumed something beyond is pulling it down. Samanthban led me to the area containing PQ21 and PQ23 Mosfets and what I think may be the power IC PU8. I checked around that area and didn't find anything definite so I decided to remove PQ23. I put PQ10 back and applied power. PQ23 was not the problem so I removed PQ21. Voltage still being pulled down at PQ10. So am I right in thinking it must be PC80, PC81, PC82 or PC83? Or am I confusing myself.

[clearchris]

Re: Dell Inspiron 5150 Laptop

After the repairs I have made to the blown diodes and bad power jack, it seems that we are exhibiting the same symptoms.

What voltages do you see at all pins of Q33?

[MEB]

Re: Dell Inspiron 5150 Laptop

samanthban, clearchris and any others...

sorry to disappear on this thread. My son drove his truck through a large puddle and water locked his engine so being the good father I try to be, I have been trying to resurrect it before winter. here is a photo of where I am at.

I will be back to fix this laptop, hopefully next week.

[clearchris]

Re: Dell Inspiron 5150 Laptop

Oof. Hydrolocked engine. Thats no fun at all. Good luck.