Re: smd precision resistor "paint layer" peeled off while soldering *** advice needed ***


Ed Breya
 

If the over-coating on these SMDs has floated or burned off, then it's likely due to being undercut by the corrosive, leaked electrolyte. This stuff can travel considerable distance by capillary action on the surfaces. From your description of the resistors affected, they are fairly high precision, metal film types. The paint flaking off indicates the metal films have been compromised by the corrosion, so may be out of spec - they would tend to be higher in resistance due to missing some of the metal. Try to measure the values in-circuit, as accurately as possible, considering the associated circuitry.

If you get everything properly cleaned up and working again, you can measure the operating voltages in that section, and assess whether the resistors are still OK. If good, just leave them alone.

Ed

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