[sdiy] NJM2068 gone bad

[Jay Schwichtenberg]

Between 1995 and 2000 we used maybe 20K to 30K of them in audio products 
without issue.

Could be a bad part, that happens.
You said diode, not diodes for the ESD protection. Is it only a single 
side protected against ESD?
Hand soldered? Check soldering.
Sockets? Check sockets. Most people don't realize that IC sockets are 
not rated for more than a few insertions/removals.
If this is in an inverting op-amp circuit having an 'open' feedback 
path/resistor can cause this.

Jay S.

On 6/24/2020 10:21 AM, Frédéric (Opensource) wrote:
> 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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