[time-nuts] FE-5680A at WA7KGX
Peter Bell
bell.peter at gmail.com
Thu Dec 22 01:00:06 UTC 2011
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
<caf at 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 caf at 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
>
>
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