Help a newbie with his first project

[jacobtc]

So, I recently acquired a Alienware 15 R1 (LA-B753P) as the guy told me it was completely dead, and I saw it as a fun project.

I have done every ordinary thing, such as resetting CMOS and leaving the RTC battery out for a while. It is completely dead, no light, nothing. The powersupply outputs 19.5V and the DC plug measures fine. I have inspected the board, and nothing seems to be obviously damaged, no burn marks, and no apparent water damage. The next step is to check for shorts, however, how would I go about doing that? I don't have a bench powersupply, so it is difficult for me to inject voltage and check with alcohol evaporation etc.



Anyone willing to give a bit of guidance?

[caspian]

Re: Help a newbie with his first project

is there any other voltages on the mainboard?

[jacobtc]

Re: Help a newbie with his first project

is there any other voltages on the mainboard?

What do you mean? Plugged in to the DC adaptor?

[caspian]

Re: Help a newbie with his first project

measure voltage on big coils and capacitors to see whether there are any voltages on the board other than the 19v.

[jacobtc]

Re: Help a newbie with his first project

measure voltage on big coils and capacitors to see whether there are any voltages on the board other than the 19v.

Will do that later! Just got back from work... Thank you so much! Really hope I can get this working!

[jacobtc]

Re: Help a newbie with his first project

So just got done meassuring some coils and caps. Where I have not written anything is due to also being 0V.

https://i.imgur.com/40dINwh.jpg

Also, nothing felt varm to the touch.

UPDATE: I did not feel around the lower right corner, that gets really hot, around the two medium sized coils...

[jacobtc]

Re: Help a newbie with his first project

These get hot:
https://i.imgur.com/ao3Unj3.jpg

PL102
PL101
PC107
PC108

[dspok]

Re: Help a newbie with his first project

check resistance to ground on those coils. it looks like those coils are for ALW voltages, not sure though because I can't find schematics.

[jacobtc]

Re: Help a newbie with his first project

Also, on the back, the IC called PU100, is getting burning hot, I can't keep my finger on it...

[jacobtc]

Re: Help a newbie with his first project

check resistance to ground on those coils. it looks like those coils are for ALW voltages, not sure though because I can't find schematics.

PL102 resistance to ground is 0.5 kOhm and increasing constantly, PL101 resistance to ground is 2.8 kOhm and increasing. I guess they are getting more resistant, due to getting colder over time? If I plug in power, they go down to 5ohm on PL102 and around 96ohm on PL101 when they become slightly warm.


This is the IC on the back that gets way to hot to touch: https://i.imgur.com/hJbHhtS.jpg

[jacobtc]

Re: Help a newbie with his first project

Anyone?

[caspian]

Re: Help a newbie with his first project

Now, you should read what is marked on top of the IC to identify it.

[jacobtc]

Re: Help a newbie with his first project

Now, you should read what is marked on top of the IC to identify it.

The IC has the following written on it: 3h=2b q2b

Now, I've searched for the PU100 IC, and another forum says that it is a TPS51285BRUKR...

[caspian]

Re: Help a newbie with his first project

it does not seem to be TPS51285BRUKR. or maybe it is. I do not know. I hope someone help identify it.

[jacobtc]

Re: Help a newbie with his first project

it does not seem to be TPS51285BRUKR. or maybe it is. I do not know. I hope someone help identify it.

This guy identified it as TPS51285BRUKR

https://ascnb1.ru/forma1/viewtopic.php?f=31&t=130165

[vinceroger69]

Re: Help a newbie with his first project

This guy identified it as TPS51285BRUKR

https://ascnb1.ru/forma1/viewtopic.php?f=31&t=130165

data sheet

[jacobtc]

Re: Help a newbie with his first project

data sheet

The package looks different to what is in the data sheet, this one has five pins on four sides, the one on the data sheet has only pins on two sides.

[Johndill]

Re: Help a newbie with his first project

The IC has the following written on it: 3h=2b q2b

Now, I've searched for the PU100 IC, and another forum says that it is a TPS51285BRUKR...

Is this the correct schematics for your board?

PU100 page 60.

[JaroTech]

Re: Help a newbie with his first project

Hi, the code '3H =' comes from Richtek, the chip is a RT6585B, it is compatible with the chip TPS51285B.

[jacobtc]

Re: Help a newbie with his first project

Is this the correct schematics for your board?

PU100 page 60.

Looks like it, thanks!