>From Dick's report, sure sounds to me like a dead op-amp. I'd suggest
getting more than one spare IC, too, since they're now obsolete. They'll go
from 'hard to get' to 'bloody impossible at any price' quite quickly.
One good rule about analogue ICs: second sources rarely really are.
Sometimes, they are 'good enough', and other times, no good at all,
depending on the exact circuit topology. Examples are a commercial HF rx
which only worked with Motorola MC1747 (dual 741), not with other mfrs 747,
which is supposedly an exact second source. Another one was a NBFM data rx
using the CA3089; they made 25,000 with LM3089 (supposed exact second
source) and when they started testing, they changed 25,000 ICs from National
to RCA! But other rx's can interchange them without problems. Similarly,
I've seen problems with 723 regulators and stability, depending on
manufacturer and circuit layout and design.
73
Peter G3RZP
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|