I have a circuit board with a surface mounted inductor which I believe is a film inductor. The board is not working properly and there is a loud squealing sound coming from said inductor so I am trying to replace it. I have located it in the data sheet for the board but I am inexperienced at identifying and specifying inductors so I am having trouble identifying a suitable replacement or testing the inductor to confirm that it is indeed the malfunctioning component. Could anyone here advise on how to determine the specs of the inductor, how to make sure I find a replacement that is suitable, or how to test the current inductor to make sure it is actually the malfunctioning component? Advice on any of these topics would be much appreciated, pictures are below for reference.

The inductor says 2R2 135S as far as I can tell and the schematic has two annotations to the component: FDA1055-2R2M=P3 and IND-2D2UH-100-GP.

The only thing I have been able to find on my own is that the inductor must be 2.2 uH (That's what the 2R2 is, I think) but I'm not sure of any other specs.

Inductor Pic Circuit Diagram

  • 1
    \$\begingroup\$ Are you sure the inductor is broken? How loud is the sound coming from it? Is the sound steady or pulsating or something else? High-pitched sounds are not uncommon from inductors that are in the path of large switching currents. \$\endgroup\$ – marcelm Sep 18 '17 at 18:50
  • \$\begingroup\$ First figure out if that one is really broken, a whining smd inductor usually is only a symptom of another problem \$\endgroup\$ – PlasmaHH Sep 18 '17 at 18:54
  • \$\begingroup\$ What is the test history and condition that causes this. It is usually a load condition like a boost converter or step pulse load overcurrent \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Sep 18 '17 at 18:57
  • \$\begingroup\$ the part is 4 yrs old so it must have been good until you loaded it on the 5V rail. Something you're hiding from us? Can U guess? \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Sep 18 '17 at 19:11
  • \$\begingroup\$ Thanks for the comments! Per some of the discussion here I think it is likely that you guys are right and that another component is shorting or otherwise overloading. @TonyStewart The part was good and I realize now that the inductor probably isn't going to be the component to fail. I'll do some more testing and see what I come up with. \$\endgroup\$ – Adept Morrow Sep 19 '17 at 19:09

This is NOT a "film inductor", it is a standard wirewound high-power inductor. A simple Google search says it is FDA1055-H-2R2M=P3 made by Murata,

"Fixed Inductors 2.2uH 4.8mOhms 15.5A +/-20%"

and available at Mouser (and many other places)

However, it is highly unlikely that the faulty inductor is the root cause of your problem. First, this is a 16-A power supply. It needs some qualification to fix it, it could be transistor problems, or snubber cicuits deteriorated, tantalum caps expire (one of caps, TC8, seems a bit burned out). Or it could be nothing wrong at all. The board seems to be some high-density laptop mainboard. It is very likely that some very large chip has developed an INTERNAL problem with +5V rail, and it would be impossible to fix it.

As an exercise, you can try to identify the source of overload by looking at excessive power dissipation, the guide can be found here, at SE.

|improve this answer|||||

Not the answer you're looking for? Browse other questions tagged or ask your own question.