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How to identify the value of a SMD (surface-mount device) resistor soldered on a board and without marking? I suppose it is in 0603 package considering my measurements.

Is there a way to do that? Or should I remove it from the board, test it, and put it back?

The context is that I have a Phottix Mitros+ speedlight flash which had an internal damage (a small explosion) when a screw came into contact with an internal circuit board. I have another fully functional flash on which I clearly see a SMD resistor and I would like to identify what is the value of the resistor to replace the one that grilled in the damage flash.

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    \$\begingroup\$ Do you mean SMD/SMT (surface mount device/surface mount technology)? SMC is a diode package. \$\endgroup\$ – DerStrom8 Aug 2 '17 at 10:47
  • \$\begingroup\$ @DerStrom8 I meant SMC as Surface-Mount Component but I just realise the correct name is SMD as in Surface-Mount Device. Sorry. \$\endgroup\$ – Alia Spencer Aug 2 '17 at 10:51
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You have to unsolder the resistor, otherwise your measurement will be false due to alternative current paths on your PCB

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  • \$\begingroup\$ I thought about that. Would it be the same for a MLCC capacitor also soldered on a board and without marking? \$\endgroup\$ – Alia Spencer Aug 2 '17 at 10:55
  • \$\begingroup\$ yes, but you can test it yourself. Measure the components while they are soldered and than measure the components while they are unsoldered. \$\endgroup\$ – S.G Aug 2 '17 at 10:58
  • \$\begingroup\$ What would be the point of testing it while it is soldered if I have to unsolder it anyway? \$\endgroup\$ – Alia Spencer Aug 2 '17 at 11:01
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    \$\begingroup\$ The point is called "learning-effect" ,-). It is always better to see results, or differences with your own eyes to keep them in mind in future.. \$\endgroup\$ – S.G Aug 2 '17 at 11:04
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Another option is to desolder something else on the PCB so that there is no current path from the resistor in question. Other components may be bigger and easier to work with.

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