How to replace the regulator (U5) on AVNET Azure Sphere Starter Kit!

peterfenn

bwilless

Hi folks, any insights regarding the above question?

Thanks for the BOOST!

But why isn't anyone interested in repairing this component!

If you know enough to be sure that this is the problem, then I'm surprised that you're confused how to replace it. It seems to be a 14 pin QFN style (i.e. no leads) package. It should be possible to replace it using a hot air rework station. Personally, I wouldn't want to try with a soldering iron but it might be possible.

Well see I did like what you said but is it possible to connect something externally without removing the component!

As I don't own a hot air gun. I do have a soldering gun but that's gonna be really difficult as the component is too small to be removed with any soldering gun!

xeonaj  wrote:

 

but is it possible to connect something externally without removing the component!

 

Hi Alphons,

I can help you find out how to help yourself : )

The easiest way is to search out the schematic of the board, and look up U5. Once you have the part number, you can search out the datasheet for the chip, and see what the pins do, and see if you can probe with a multimeter to confirm that it really is faulty, before you try to remove or modify the board.

If you have no multimeter, borrow one. If you cannot borrow one, buy one. They are only $5 USD.

You can also consider the failure conditions. For example, the data sheet may state the part is short-circuit-proof. Then you need to consider, was power applied the wrong way, or could something else have damaged that chip that you're assuming to be faulty? Just because a part gets hot doesn't mean it is faulty. Some parts are supposed to run hot in a design, or it could point to a fault elsewhere. Touching with a finger only tells you a part is hot, not that it is abnormal, or faulty, without further knowledge of the part or what it does (read the datasheet).

Once you have confirmed it really is faulty, then consider your options (including returning the board under warranty if you purchased it, if a warranty return is feasible in your country). If you are down to the option of "doing something externally" then you need to see if you have the capability to attach an external circuit that can replace the functionality, whether you need to remove any parts or cut any tracks, and whether you have the ability to solder down to the fine tracks that are on the board.

The way you're going about it, is not usual (or at least has a low chance of success) without doing the due dilligence in the steps outlined above, so you should strongly consider the above - this is just an opinion.

I understood what you said!

OKAY I just got my hands on a multi-meter tested the current flow across the board! (Visited my neighbor they run a mobile repair shop)

The current goes over 5.xxx on component C8.

U5, C10 doesn't show any changes.

And as far as I know U5 is the regulator which converts 5v to 3.3v.

So if replaced should work good back to normal but I seriously dont know how to remove this component and attach something else!

And about the heat, it heated just once or twice after it never responded in any way.

I had recently worked on a small project were I had to solder some capacitors and regulators on educational soldering board. There I had put the regulator the wrong way after powering the circuit it become very hot and automatically switched off, never worked again!

Thank You! But please somebody with an experience please help!

Sir even if I manage to remove the component what should I use in its place! Of-course it wont run without that very component!

MIne is a QNF 18 - MPM3822CGRH - ULTRA SMALL STEP DOWN MODULE 6V 2A QFN-18

Hi Alphons,

This is a great start! Now you can move on to the next step, reproduced here:

Once you have the part number, you can search out the datasheet for the chip, and see what the pins do, and see if you can probe with a multimeter to confirm that it really is faulty, before you try to remove or modify the board.

(To be clear, I think you should do this step, because then you'll know what to do for the next similar issue you ever encounter).

(1) If Drop-In Repair

I typed your part number into the internet and found this in 15 seconds: https://www.avnet.com/shop/emea/products/mps/mpm3822cgrh-z-3074457345642032999/

Luckily the device could be hand soldered IMO as the two hidden pads are marked in the datasheet as DNC which means Do Not Connect.

There is loads of helpful comments on Element14 for soldering SMT....[ps: you'll need plenty of liquid flux, magnifying lens, a fine tipped soldering iron, thin solder, desolder braid and coffee]

(2) External Supply

If this is your chosen route, you'll need to work out what voltages the MPM3822CGRH device was supplying, what currents were being drawn by your board to enable you to find or build a replacement.