[sdiy] NJM2068 gone bad

Frédéric (Opensource) marzacdev at gmail.com
Wed Jun 24 19:21:29 CEST 2020


Hi to everyone,

In a client audio design, I used a NJM2068 dual op-amp
as the input signal conditioner before the ADC circuit.

The op-amp is powered with symmetrical supply rails (+12V, -12V)
provided by the power bus of an eurorack system.
Rails are protected by series shottky diodes therefore the
case of a polarity reversal can be discarded I presume.

Audio input has an ESD protection diode and the impedance
between the + input of the amp and the input jack tip is about
20k (resistor). The input is specified for "eurorack level" signals.

Unfortunately, after the field tests, we got back one module
whose input op-amp had a defective channel. Input signal would
be saturated while being far away from the rails.

Had any of you a bad experience with this component?

I am also open for all suggestions about what wrong could
have happened?

Best from Bonn,
Frédéric




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