dell inspiron 15 5578 memory or systemboard error

[bingbadaboem]

hello all,

got a dell inspiron 15 5578 which had a bios issue which is hopefully sorted.
I did however find three fried components on the mb.
the system indicators indicate systemboard or memory fault.
the fried components on mainport are on the picture and marked:

pr5420
pc5411
pr5419

Now the question is what are these and where could I get those parts so I can soder new ones in.
the mainboard p/n: 0pg0mh

thanks,

[petehall347]

Re: dell inspiron 15 5578 memory or systemboard error

you will likely find they got sacrificed because something else went shorted . so replacing might make things worse .
wait for someone that has time to check the schematics if available

[Techtiger]

Re: dell inspiron 15 5578 memory or systemboard error

2 Resistors ,1Capacitor non polore blown out , PR stands for POWER, You can replace it higher value or from a donor board , for the cap if one side is ground you can leave it , for the resistors if you understand what is a resistor !you can Bridg them but that’s up to you taking that Risk

[bingbadaboem]

Re: dell inspiron 15 5578 memory or systemboard error

Don't know the reason they blew. The board looks fine on all other points.
If I only had a donor board...
Without schematics its hard to tell for me but the part seems related to the memory slots. Rather not bridge the resistors.

[mcplslg123]

Re: dell inspiron 15 5578 memory or systemboard error

Yeh, Without schematic its difficult. Is there any IC just below the burnt area(i mean on the other side of the board)?? If so, then which IC??

[bingbadaboem]

Re: dell inspiron 15 5578 memory or systemboard error

Yes there is a chip on the other side, it reads: apl5930 pt2cx

[mcplslg123]

Re: dell inspiron 15 5578 memory or systemboard error

What is the readings on APL5930-ALL 8 Pins?? Next step should be to remove all the burnt element and check connectivity with apl5930 pins. That will give an idea about the signal line which is affected. cap we can ignore for the time being, we need to findout out about the two resistors in the picture.

[mcplslg123]

Re: dell inspiron 15 5578 memory or systemboard error

Here is the datasheet for APL5930

[bingbadaboem]

Re: dell inspiron 15 5578 memory or systemboard error

Hi thanks for the datasheet.
This are my findings:

Gnd to fb - 0 V
Gnd to both Vout - 0 V
Gnd to en - 192.2 mV
Gnd to pok - 0 V
Gnd to Vcntl - 5.2 V
Gnd to Vin - 1.51 mV

Also posted better pic of area

[mcplslg123]

Re: dell inspiron 15 5578 memory or systemboard error

The readings are not correct in value. VIN must be 5V. Since you dont have vin, there is no question of having vout or en signal etc. I'll suggest to remove all the burnt components first from mobo and then recheck voltage on apl5930. If VIN still missing, you can try to jumper its VIn pin to any 5v source from motherboard and see if it switches correctly and other voltages appear on APL5930. Remove ram from dimm slot to avoid any damages while experimenting.

[bingbadaboem]

Re: dell inspiron 15 5578 memory or systemboard error

I cleaned the burned area and now get the following readings:

Gnd to fb - 0 V
Gnd to both Vout - 3.37 V
Gnd to en - 3.37 V
Gnd to pok - 7.19 mV
Gnd to Vcntl - 5.24 V
Gnd to Vin - 3.37 V

Also pr5420 seems ok - at least I read 13.68 kΩ both ways.

[bingbadaboem]

Re: dell inspiron 15 5578 memory or systemboard error

Looking at the schema of the ic an I correct to assume we are looking at r1 r2 and c1 in the burned area?

And that

pr5420 = r2
pc5411 = c1
Pr5419 = r1
?

Also checked the copper collored connection next to the pr5419 writing it reads 3.37 V

[mcplslg123]

Re: dell inspiron 15 5578 memory or systemboard error

ok, so atleast some progress. i think PR5420=R1 and Pr5419=R2(Not sure though-we can try altering the resistors also later on). So lets put these two resistors(12K and 24K) and see how the mobo behaves.

[bingbadaboem]

Re: dell inspiron 15 5578 memory or systemboard error

Ok I don't have the resistors in so Will have to order Some. Will be Some time.
What tolerance should they be?
Also for the cap. Will order that in also cause that Will take Some time too.

[bingbadaboem]

Re: dell inspiron 15 5578 memory or systemboard error

Finally got them in. You was right about the position of the 12k and 24k resistor.
I did not place the cap as I couldn't get one of the pads clean and ok. Don't have the tools for it, but it states optional on the chip info.
Any idea of the risks involved not having one in?

Best part is that the laptop runs again 😁
Hope it will have a long life ahead.

Thanks for helping out 👍

[mcplslg123]

Re: dell inspiron 15 5578 memory or systemboard error

Finally got them in. You was right about the position of the 12k and 24k resistor.
I did not place the cap as I couldn't get one of the pads clean and ok. Don't have the tools for it, but it states optional on the chip info.
Any idea of the risks involved not having one in?

Best part is that the laptop runs again 😁
Hope it will have a long life ahead.

Thanks for helping out 👍

Feeling happy for you friend. You can ignore the cap-wont harm.