Wow, no limits on the reverse engineering capabilities of this group... amazing, now where is Elio? He must be interested in this. [I have no FE5680A but followed the heavy posting about it, I prefer the LPFRS Rb]
On Sat, Mar 17, 2012 at 2:12 PM, J. L. Trantham <[email protected]> wrote: > Rich, > > I would love to have a set of the pictures. > > Joe > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Rich > Sent: Friday, March 16, 2012 3:05 PM > To: [email protected] > Subject: Re: [time-nuts] FE5680A > > > This is my first post here. Unfortunately I found this informative group a > bit late. > > I got from e-bay a similar unit to yours with an identical pin-out from the > e-bay listing. As in your case I did not get a 1pps output and there were > no > lock indication although the 10MHz initially wandered and after 5 min or so > it locked. > > I opened to unit and traced a good part of the circuit with the aid of > about > 25 high resolution x-rays of the board. I mounted them on a wall in my > workshop and created a composite high def x-ray about a yard across. This > is > excellent to follow traces below the ICs and in the board layers and vias. > Don't know if I can post attachment but I'll try one to give you the idea > with a jpg of the layout. Should people be interested I can post all of the > 25-30 x-rays of the pc board on a website for those who would like to trace > or troubleshoot the overall circuit without having to remove the chips. > > Finally found the Fairchild 74ACT240 to be the culprit. It was pulling down > the lock circuit and preventing the 1pps from coming out. Seller must have > damaged it and that is why it was at a such low price I guess. > > I now use a 330 ohm resistor in series with a LED and the lock indicator > work fine and well as the 1pps. > > As to the RS-232 I get a response using 960 n 8 1 as outlined in these > forums. Did not dare changing the frequency yet until I get a higher > precision setup that will actually measure the change. No quite there yet. > > Hope this is useful for some of the members. > > Richnormand > > > _______________________________________________ > 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.
