[Boatanchors] CMOS Failure

[Rob Atkinson]

Possibly inferior manufacturing conditions.  Or, the case holding the
chip isn't perfectly sealed.  These two problems are the enemy of
components going back a long time and are not tied exclusively to
CMOS. CMOS failure is the Achilles heel for other items, especially
anything with a custom designed and manufactured chip.   Kenwood
TS-850 for example.

It would be interesting to note if the failed chips always are from
one manufacturer.

The good news for the 9100 is that the bad chips must be common
components that can be replaced.

This is interesting
https://www.edn.com/electronics-news/4382044/What-Causes-Semiconductor-Devices-to-Fail-
Scroll down to the bullet point:
"A discharge causes “latch-up” in a CMOS device due to triggering of
silicon-controlled rectifiers (SCRs). "

73

Rob
K5UJ



On Sun, Mar 17, 2019 at 11:33 AM Paul Christensen <w9ac at arrl.net> wrote:
>
> While repairing items from the 1980s decade, I've found several instances of
> failed CMOS logic gates.  Just recently, I repaired an Orban 9100B audio
> processor that had three bad CMOS chips.
>
> Each CMOS device is in an intra-stage part of the processor, meaning they
> are not exposed to the outside environment as is the case when connected to
> an input or output jack where conditioning is minimal or non-existent. The
> power supply tests fine.  Regulated voltages are spot-on and supply ripple
> is less than 1mV RMS.  Internal temperatures are warm, but not excessively
> hot.
>
> This is only the most recent occurrence.  I've seen similar failures in the
> last few years.  Does anyone on the list have an understanding of the
> failure mechanism?
>
> Paul, W9AC