HI Ok, so to fully evaluate the problem, you will need to de-encapsulate the parts. That *is* the next step in this adventure. First pass would be to pull the plastic off of a couple of bad ones and get some pictures of the die. After that, trace them back and see if they are Brand A or Brand B. Next, do the same for a good one (or two) and see if the die trace to the same manufacturer.
Next after the die are traced down would be probing with something like a Cascade probe system. You can get them that are alleged to be good into the > 20 GHz range. Team that up with some low noise test gear and you will be able to rule in / rule out the regulator it’s self. Yes this is a bit expensive. If you want to troubleshoot the issue, it is the next step. It’s a whole lot easier to swap out the regulator for a different one and just move on. Bob > On Dec 8, 2016, at 11:37 AM, Van Horn, David > <[email protected]> wrote: > > I did check the circuit through the whole range that it should operate in, > based on component data sheets. No issues. > I also carefully varied the voltage right around where the regulator output > is, to see if there was some very narrow band of sensitivity. > Nothing. > > -----Original Message----- > From: time-nuts [mailto:[email protected]] On Behalf Of Joe Leikhim > Sent: Wednesday, December 7, 2016 12:31 PM > To: [email protected] > Subject: Re: [time-nuts] Totally unrelated, but.. > > Could the low noise parts actually be counterfeit, relabeled as such? > > Is the circuit the regulator feeds sensitive to a narrow band of voltage that > the "good regulator" is outside of? > > Try replacing the regulator with a battery supply and resistor divider to > attain the working voltage. Move the voltage around. A good potentiometer and > stiff filter capacitors are recommended so as not to introduce "pot noise". > > Is something corrupting your test procedure? I had a circuit that misbehaved > due to floating logic pins reacting to static electricity on the work bench. > Another time a diode was photosensitive. > > > > -- > Joe Leikhim > > > Leikhim and Associates > > Communications Consultants > > Oviedo, Florida > > [email protected] > > 407-982-0446 > > WWW.LEIKHIM.COM > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
