[Boatanchors] CMOS Failure

[Bill Cromwell]

Well golly,

I have a couple of coffee cans full of new-old-stock CMOS. I am 
wondering if I should dump all of that or take the trouble to run some 
functional testing. I have a big stack of vacuum tubes and all of them 
pass minimal testing (or they are gone). Aside from designing Arduino 
routines for the various ICs does anybody have suggestions where to 
look? I am NOT buying a kilobucks tester for a couple of coffee cans 
full of old chips. Buying new ones would be much more cost effective. 
Building something like an arduino test board would have more value with 
the mental exercise and the reusable/reprogrammable parts. Have the 
routines already been worked out?

73,

Bill  KU8H

On 3/17/19 1:10 PM, Rob Atkinson wrote:
> 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
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-- 
bark less - wag more