Dell Inspiron 5160 - power jack and aftermath

[clearchris]

Hi. I was in a different thread, but out issues have diverged, so I'm starting my own thread. The schematic for my 5160 board (same as 5150) is in the original post here:

https://www.badcaps.net/forum/showthread.php?t=49318

So, what I see on my board is are badly cracked solder joints on the power jack, a physically blown schottky barrier diode, and a partly melted zenier diode.

My plan is to first replace all the obviously blown parts.

My question to start is: After looking at this schematic, the blown diode is part of the lead up to CPU CORE. Does this mean the CPU is probably fried?

Here's the relevant part of the schematic:



Thank you!

[Th3_uN1Qu3]

Re: Dell Inspiron 5160 - power jack and aftermath

That diode is there specifically to protect the CPU, so it has likely survived. However, if that blew, you may have a short on the CPU VRM. Check the two high side mosfets, PQ89 and PQ90 in your schematic.

[clearchris]

Re: Dell Inspiron 5160 - power jack and aftermath

Thanks!

PQ90 is going to be easy to test, it's not filled on the board. I'm looking for 3.3v on the 6,2,1,7 pins of PQ89, right?

What are the important ratings of a diode, and are there any that I can safely increase / decrease (like how you can increase voltage on a cap without affecting the circuit)?

I can't find the specific diode except in china.
https://cdn.badcaps-static.com/pdfs/...766c7b8bd9.pdf

Here's what I'm considering. I increased the forward current to 5A (is that ok, like upsizing a relay?)
https://cdn.badcaps-static.com/pdfs/...a0589b6289.pdf

Also can't get this:
https://cdn.badcaps-static.com/pdfs/...1475bfc5c2.pdf
So I want to substitue this:
https://cdn.badcaps-static.com/pdfs/...c8800232bf.pdf
They are both zener 5v 1/2watt. The mouser one is through-hole, I'll just have to make it work.



Thanks again!

[fddizon]

Re: Dell Inspiron 5160 - power jack and aftermath

modifying diode's working specifications might make a problem in terms of its functionality as protection.

[clearchris]

Re: Dell Inspiron 5160 - power jack and aftermath

The original specification is 4.71 for forward current. I can find 4A and 5A diodes domestically. Would you suggest going up or down, or waiting a month for the exact part from China?