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I would appreciate some help. I am trying to fix a board for a friend and the problem is that a component has been knocked off the board. You will see the missing E2 component in the image below. E6 looks like the same component.

My initial thought is that it's a capacitor but I don't understand why it would be referred to as "E" when you can see "C1" in the image towards the bottom of the image.

I can always remove E6 but I need to understand the type of component in order to measure its value.

Cheers, Crom

PCB with missing component E2

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    \$\begingroup\$ Very odd, E11 and E5 are also caps... Perhaps it indicates electrolytics \$\endgroup\$ – Trevor_G Mar 21 '18 at 14:26
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    \$\begingroup\$ E5 does indeed look like a tantalum cap. But so does C54. \$\endgroup\$ – Marcus Müller Mar 21 '18 at 14:31
  • \$\begingroup\$ @MarcusMüller ya looks like someone had an idea but then didn't continue with it when copy and pasting. \$\endgroup\$ – Trevor_G Mar 21 '18 at 14:47
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Boy, comparing E6 to E12 it looks darker than the other (1206/1210) MLCC caps so it could be a ferrite discrete device. Try measuring E6 on Ωs scale to see if you get a reasonable value (10s or 100s of Ωs) consistent with a ferrite instead of a cap.

This (my) assumption is based on that the E2 and E6 circuits look to be similar.

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Steve beat me to the same conclusion.

Note the rounded diffusion of end terminals and dark iron oxide colors are trademarks of ferrite beads used in SMPS regulators to absorb switching noise by raised impedance with f but conductive with low resistance at DC.

Due to the wide mix of iron, nickel and insulation, there is no way to predict and it all depends on the rated DC current.

Example Kemet parts

 Ordering Code Inductance (μH)Inductance Tolerance Minimum Self Resonant Frequency (MHz) DC Resistance(Ω Ω) (±30%)Maximum Rated Current (mA) MeasuringFrequency (MHz) Tape & Reel Packaging Quantity  
 L1007C1R0MPWST 1.0 ±20% 100 0.06 500 7.96 2,000
 L1007C1R5MPWST 1.5 ±20% 80 0.07 400 7.96 2,000
 L1007C2R2MPWST 2.2 ±20% 68 0.09 340 7.96 2,000
 L1007C3R3MPWST 3.3 ±20% 54 0.11 270 7.96 2,000
 L1007C4R7MPWST 4.7 ±20% 46 0.13 240 7.96 2,000
 L1007R4R7MPWST 4.7 ±20% 46 0.10 235 7.96 2,000
 L1007C6R8MPWST 6.8 ±20% 38 0.15 195 7.96 2,000
 L1007C100MPWST 10 ±20% 30 0.25 165 2.52 2,000
 L1007C150MPWST 15 ±20% 23 0.32 145 2.52 2,000
 L1007C220MPWST 22 ±20% 19 0.50 115 2.52 2,000
 L1007C330MPWST 33 ±20% 15 0.70 95 2.52 2,000
 L1007C470MPWST 47 ±20% 12 0.95 85 2.52 2,000
 L1007C680MPWST 68 ±20% 9.5 1.50 70 2.52 2,000
 L1007C101MPWST 100 ±20% 9 2.10 55 0.796 2,000
 L1007C151MPWST 150 ±20% 7 3.20 45 0.796 2,000
 L1007C221MPWST 220 ±20% 5.5 4.50 35 0.796 2,000
 L1007C331MPWST 330 ±20% 4.5 7.00 30 0.796 2,000

enter image description here

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  • \$\begingroup\$ You read my mind. \$\endgroup\$ – Steve Mar 21 '18 at 15:43
  • \$\begingroup\$ Steve did you work in Rockaway NJ at HP>? \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Mar 21 '18 at 15:45
  • \$\begingroup\$ Tony. I did work for HP (in Liberty Lake, WA) but not in NJ. \$\endgroup\$ – Steve Mar 21 '18 at 16:43

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