0
\$\begingroup\$

I am trying to fix a RS485 circuit. There is 3-pin protection components on both A and B pins. The component is connected serially to the line and mid pin is grounded. There is no label on the component.

The resistance is nearly 0 ohm and the component is short circuit by defult.

Could you please help to identify this component?

Protection Component Schematic

|improve this question
\$\endgroup\$
  • \$\begingroup\$ Short circuit between which pins? \$\endgroup\$ – winny Jul 9 at 12:09
  • \$\begingroup\$ the resistance between the firs and third pin is 0.5 ohm. mid pin is grounded. I heated the component to 300 Celcius but the resistance didnt change. \$\endgroup\$ – Mustafa Aygün Jul 9 at 12:12
5
\$\begingroup\$

It quite likely is one of the NFE series of Murata.
Looking at the size, I guess NFE61PT 2706(6816).
The chip "EMIFIL" NFE61PT is a T-type circuit EMI suppression filter.

Bad quality image from the datasheet reveals the low DC resistance you're measuring between input and output. Therefore, I think it's quite likely the component is not broken.

enter image description here

|improve this answer
\$\endgroup\$
  • \$\begingroup\$ Yes this is a EMI suppression filter. But as there are no markings on the device it is impossible to know which exact device it is. \$\endgroup\$ – Justme Jul 9 at 12:33
  • \$\begingroup\$ @Justme True. The same applies to SMD resistors. You never know exactly what component has been used. Therefore I wrote: it quite likely is one of the NFE series. OP should confirm the components dimension with the datasheet's dimensions and could further desolder it and measure the insertion loss using a spectrum analyzer. \$\endgroup\$ – Huisman Jul 9 at 12:52
  • 1
    \$\begingroup\$ But as I just edited: the component is likely not broken, so probably an exact part number isn't required as there is no need to replace the component. \$\endgroup\$ – Huisman Jul 9 at 12:52
  • \$\begingroup\$ Indeed, based measurements that component is not the problem. \$\endgroup\$ – Justme Jul 9 at 12:56
  • \$\begingroup\$ @Huisman, thanks for your help. The component is exactly Murata NFE. The part number isn't important because the component is working. \$\endgroup\$ – Mustafa Aygün Jul 9 at 16:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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