"Arfa Daily" schreef in bericht
...




Didn't you walk right into the problem? It seems that by a yet unknown
cause the circuit sometimes runs into some state that makes it oscillate
or in some other way fries the resistors. This kind of intermitted faults
are the most difficult to solve as most of the times there seems to be no
problem. Even your observations with the scope may mislead you as
connecting the probe may change the circuit enough to change its
behavior.

petrus bitbyter


Yes, there may indeed be some kind of intermittent problem. I will put
them all back up again on Monday, and see how they perform this time. As
to my 'scope muddying the waters, it's generally pretty well behaved in
that respect. It's a high quality 100 MHz job, which is always used with a
x 10 low capacitance probe. If that is having much of an effect on the
circuit, then it must for sure be a pretty poor design. To be honest, I
still think that the problem lies with me somehow. Something that I did
differently between the first and second times that I tried them, but I'm
not sure what ...

Arfa

Off course you may have made a mistake. Humans make mistakes, even I
sometimes do
But if so, what on earth fried those resistors the first time?

petrus bitbyter