Blown Inductor - HP Envy 17 - J184NA

[pjzz2000]

Hi

Totally new to this website/forum, so apologies if not the appropriate place to ask, but.....

I'm trying to diagnose my son's laptop motherboard.

Power jack led on, power button led on, but I think post fails. CPU cold and no voltage around CPU graphics card.

I start to suspect power rails, or PCH or CPU.

I did a close visual check and find an inductor that looks in a sorry state, next to what I think might be the PCH. I can only see 2R2 I (or L), but from reading, this is not enough to identify the various specs required to get a like requirement.

I have no board schematic or board view.

Can anybody help with what to look for? I don't want to blow up the PCH, CPU and/or graphics card by guessing!

[pjzz2000]

Location of PCH and bad inductor

[SMDFlea]

Post the motherboard model number

https://www.badcaps.net/forum/troubl...r-s-guidelines
1.1.3 Motherboard model number

[pjzz2000]

Wider view

Not the bad board, I lost the photo. But this is the same location on the actual board

[pjzz2000]

I believe the bad board with bad inductor is:

For HP ENVY 17 - J184na

SPS 720266-501

[SMDFlea]

I believe the bad board with bad inductor is:

For HP ENVY 17 - J184na

SPS 720266-501

Inventec 17SBGV2D 6050A2549801 ,there`s no schematic available. The inductor is 2.2uH ,desolder it completely or on one side and lift it so the its not touching the pad, then measure the exact resistance to ground on both pads and post your results

[pjzz2000]

Thanks very much. Tried with an old soldering iron and it didnt go very well. Will need to get proper equipment, so will respond as soon as possible.

[mcplslg123]

Usually an inductor blows when there is excessive current draw.Follow smdflea's advice and remove the inductor. However, I'm afraid that very likely you'll find a short to Ground on the PCH side of inductor.If so,Then PCH has to be replaced and there may be even more damaged components. But first the resistance to GND readings on both pads of the blown inductor(after removal of inductor,no power attached).

[pjzz2000]

Thank you so much.

This is going to take time; limited soldering skills and no proper equipment, yet.

I'll be back!

[mon2]

To me, the inductor does not appear to be defective. The broken corner looks like the shield casing was chipped from a physical drop of a tool or similar event. Inductors are available in shielded and non-shielded variations. This is a shielded version.

remove all power. Meter in resistance mode. Measure the resistance across this inductor. It should be close to 0hms.

measure the resistance to ground to check if the power rail is shorted or not.

[pjzz2000]

Interesting, thank you.It's easy to jump to conclusions!

I guess the reason I suspected this one particularly, was not only that it looked sick but also that I thought it could be shorting to ground before PCH which may be preventing power or any signals to CPU to do anything.

Total guess, but sounded logical. I dont know WHEN we should expect to see voltage at all the inductors near the CpU, graphics, PCH.

The now "bad" inductor is hanging half off the mobo pending some better soldering equipment. I may have bridged the two pads in attempt to desolder, so will wait to get it off clean and then take the measurements.

I had checked resistance across all these inductors around the processors and pch and they were all 0v.

I also checked them all for resistance and all around 0.06ohms, which I gather is good (which maybe confirms what you suggest).

I'll get back to you again on once I've tidied up!

Thanks loads for your interest and help.

[pjzz2000]

Miraculously, the board looks like it might have survived.

I tries taking some measurements from the two sidea of the inductor, after removal.

In resistance mode, hardly anything useful; stays at "1", on both sides to ground, which i think is "out of range", or open loop?

I tried in diode mode to ground, left pad "554", right pad, "1".

Any ideas?

[mcplslg123]

The resistance is high enough. proceed to solder the rated inductor.

[pjzz2000]

Hi,

Problem is, the inductor looked broken which is what drew my attention to it, among other things.

And it got broken further in my desoldering, so I need to replace it.

I read somewhere that a 2R2 L can have different specifications, such as amps and, as there are no product markings and no schematic I have no idea what to buy.

it is very close to the PCH, so does that give any clue?

thanks

[mon2]

Share the physical size of this inductor. We know with 2R2 = 2.2 uH. We have found that brands like Bourns / Pulse and a few others offer higher current rated parts than offshore companies. Do also measure the height of the part. Then can go on the hunt for a suitable device. The inductor will have a normal operating current rating and then a saturated current rating. At the saturated point, the current will heat up so will be an increase in temp over ambient. We do not want this logic board to become an air fryer so best to find the highest rated device for the physical footprint.

[pjzz2000]

Thank you, I'll get on to it tomorrow.

[pjzz2000]

The measurements seem to be around:

4.6mm x 4mm x 1.5mm


I tried, ac adaptor connected and shorting power button pins.

Now that the inductor is off the board, the behaviour has changed a little:

Original problem: ac adapter led on and power button led on, a 0.5 second spin of fan, then nothing else, just frozen

With damaged inductor adjacent to PCH off the board, the fan now spins for 2 seconds, noticibly longer, followed by repetition in loop every 3 seconds.

If you know how to find a suitable 2r2 inductor with a reasonable current rating, that would be very helpful.

Many thanks

[mon2]

The inductor is required to complete the DC-DC switching regulator (BUCK mode) design. Without it, this power rail will be off.

The following should be suitable (just a bit taller) - do confirm if the height is acceptable to your enclosure.

SRP4020FA-2R2M Bourns Inc. | Inductors, Coils, Chokes | DigiKey

[pjzz2000]

I think that will fit fine, thanks

[pjzz2000]

Just tried to order a few but looks like they only deliver to Canada.

I'm in: London, United Kingdom

Update: have managed to order same from a UK importer, mouser.co.uk

Thanks