[sdiy] CMOS IC heat damage

[harrybissell]

Charles Brodeur wrote:

> One of these joints was near the IC, which stupidly enough was in the
> socket at the time. One I reconnected the circuit to my power supply,
> It failed to produce any output. Specially I was soldering near the pin
> that produces the pulse out.
>
> In your expert opinions, could I have damged the CMOS inverter chip by
> soldering near a pin while the chip was socketed?

Very slim possibility... I do this ALL the time. Sometimes I even solder
with the
power ON  (yeah I know thats a real shitey idea) and have no problems
unless
I bridge a power pin... even THEN cmos usually survives (but ota's die).

> Or should I check for
> solder bridges, which I already have done to no avail?

Solder bridge is more likely, or you may have caused an OPEN circuit by
breaking
a foil...

Best way to go is to examine what states the CMOS pins are in... and what
states they
should be in.  Also look at any unused sections of the chip, sometimes they
die and the
effect is not obvious on the good parts.   (Like you notice the circuit
does not WORK...
but the voltages are all good at the pins you are using. often you forget
to look at the
unused parts as well...)

Good luck - you will probably laugh (and learn) when you find it

H^) harry

>
>
> It was really excited this circuit was finally working. It was a real
> letdown to have something this simple ruin it. Thanks for any insight
> anyone can contribute to this problem.
>
> -Charles
>
>
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