Acer aspire v3-531 dead, b+ short?

[_RicH_]

Hi,

I have an Acer Aspire v3-531 (compal LA-7912P) which is dead, no lights at all.

Board looks good, no sign of damage or blown components.

I'm new to component level diagnostics but testing and tracing I find that B+ rail only has 0.2v, looking at the circuit diagram (found here I presume this is fed from PQ1.

VIN is good (18.6v) and PQ1 is getting around 6v at pin 3, but only 0.2v reading at pin 1.

I've checked resistance from B+ to ground and see 0 ohm - I presume there is a short? B+ feeds many areas of the laptop so what would be most likely area to cause this short?

Many thanks.

[_RicH_]

Re: Acer aspire v3-531 dead, b+ short?

After some searching I read that running some power through B+ should heat up the faulty component, so I did this and found the marked capacitor gets hot.

I cannot locate this component on the circuit diagram to find its value and replace - can anyone help?

It appears the bottom of the cap goes around to the other side of the board to 0v, the top goes to a ferrite bead (I think that's what it is) and then on to +5V for the HDD.

I cant see any ferrite bead marked on the circuit diagram for this area. My board is marked as Rev 1.0 and the circuit diagram rev 2 if it makes a difference.

Can anyone please help identify this overheating component?

[dellxps15]

Re: Acer aspire v3-531 dead, b+ short?

if u remove that capacitor, light goes up ?

check also after removing voltage on both pins