Hi, Chuck >From my investigations of the circuits, the only places the 5V goes is the 74ACT240 next to the D-type connector and the Maxim 3.3V regulator - he first thing I would check is to apply just the 5V to the unit and see if the 'ACT240 gets hot - to really confirm it, just lift pin 20 of this chip and see if the current drops.
Regards, Pete On Thu, Dec 22, 2011 at 5:27 AM, Chuck Forsberg WA7KGX N2469R <c...@omen.com> wrote: > I removed the oscillator from the circuit board using an Allen wrench > on the other side of the board. Somewhat easier than unscrewing the > obvious way, especially with a worn tool. > > I removed the lid and lifted the plastic sheet. I did not see anything > alarming. > > It is now mounted on the outside of the chassis that holds my Thunderbolt > and its switching power supply. An AC adapter from an old Toshiba laptop > provides the 15 volts. 5 volts is shared with the Thunderbolt, which draws > very little from 5 volts. A big fat line filter keeps the RFI inside. > > I have powered up the 5680A several times. The first time took about 30 > minutes to lock. Subsequent times took the usual several minutes to lock. > > As I write this the 5680 has stayed within about 50 degrees of phase lock > with the Thunderbolt's 10 MHz output for 316 minutes and counting. > Not bad for $40.00. > > Still no idea why the 5 volt draw is 340 ma instead of 90 ma. The 15 volt > draw > is normal. > > -- > Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com > Developer of Industrial ZMODEM(Tm) for Embedded Applications > Omen Technology Inc "The High Reliability Software" > 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.