[time-nuts] Trimble 57963-80-DA1 assembly.. request for schematic

donald collie donaldbcollie at gmail.com
Wed Jun 20 18:17:46 EDT 2018

Hello Ignacio! Perhaps your unit acts in a similar way to mine : I apply
power [13.6V], and immediately the leftmost "power" LED is solid "on". The
red "1 PPS" led stays "on" for a second or so, does a double flash , and
then flashes at 1PPS - Even if the ovens are not up to temperature. I
thought that the outputs were inhibited until the crystal was on frequency
to a very great accuracy. Not so in this unit. As the ACT, and ALM LEDs on
the ancilliary board don`t operate properly, because of the way they are
connected across the LEDs on the Trimble board, I`m looking at the LED`s on
the Trimble board itself. These both go red for a second or so when the
reset button is pressed, and then the ACT led goes green continuously for
about 5 minutes, and then starts flashing green - presumably when satellite
signal(s) are being recieved normally. Could you please confirm, Ignatio,
that your unit does the same. At the moment the puck active antenna is just
sitting at a high point in my workshop facing North
[I am located more than 45 degrees south at this location], so I`m not sure
if its receiving signals from satellites, or not.
I need the schematic of the 57963-80-DA1 board to see how the ACT, and ALM
LEDs are wired on this board, so that I can get the equivalent LEDS on the
Ancilliary board connected so that they work. At the moment these LEDs seem
to be wired in parallel with the appropriate LED on the Trimble Board. LEDs
wired in parallel don`t always share current well - especially if they are
different colours and hence different voltage drops.
Thankyou Ignatio, and yes, a photo might clear a few things up.
Collie jnr ZL4GX
PS : will check the wiring between pcbs

On Thu, Jun 21, 2018 at 2:32 AM, EB4APL <eb4apl at gmail.com> wrote:

> Hi Don,
> While I don't have this model, I had a problem  with my Nortel-Trimble
> NTGS50AA with similar symptoms. This was caused by the way the
> interconnection between the two PC boards, they use a flat cable with
> unkeyed connectors on it so they could be reversed. Using one of the the
> straight ways, i.e. pin 1 to pin 1 and so on, the lights worked in a
> strange way.  Using the other way, the auxiliary board in front of the main
> one and the cable straight between them, it worked ok. I can send you a
> picture if you interested.
> Regards & 73,
> Ignacio EB4APL
> El 20/06/2018 a las 13:46, donald collie escribió:
>> Hi, I just received one ex-China GPSDO`s which uses the assembly mentioned
>> above. It is nicely built, but has a design problem with the ACT
>> [activity], and ALM [alarm] LED`s on the ancilliary pcb not following the
>> LED`s on the Trimble pcb  - they don`t activate properly. Would one who
>> knows please point me in the direction of the circuit of this assembly.
>> Also, would somebody who has a GPSDO which uses this assembly, please
>> confirm the correct led status when the crystal oscillator is correctly
>> diciplined by the GPS, and "on frequency"
>> Thankyou for your concideration of this!
>> Cheers................................................Don Collie
>>                                                   ZL4GX
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