[time-nuts] Troubleshooting an HP 58503A

Azelio Boriani azelio.boriani at gmail.com
Sat Oct 13 08:39:23 EDT 2018


Try a SYSTem:PREset first, before sending the GPS:INITial.
On Sat, Oct 13, 2018 at 8:44 AM Matthew D'Asaro <medasaro at mit.edu> wrote:
>
> All -
>      I have made substantial progress on my HP 58503A, but I am not
> quite there yet. By watching the internal lights and the data on the
> processor bus I could see that the CPU was starting to boot and then
> restarting every ~15 seconds. Furthermore, the reset circuit didn't seem
> to be working right. Sometimes when I power cycled it the front panel
> lights would flash to indicate a self-test, other times they would not.
> This seemed to indicate that the system was not being reset correctly on
> start-up. More telling, when I manually triggered the reset generator
> chip, the system would not ever flash its front panel lights even though
> I could see that the CPU was being reset per the internal lights.
>
>      The problem, as it turned out, was more mechanical than electrical.
> As shown in the attached photo, someone had put the case back together
> with a screw that was too long! It dug into the board and cut two
> traces, one of which was the reset line for the UART chip (and probably
> some other chips as well - I didn't fully trace the line). Once I
> repaired these two traces (red wires in my picture) it booted right up
> and even passed its self-test!
>
>      However, the story does not end there. I now have it booting and
> appearing to "work" but I can't get it to track satellites. I manually
> set the location, date, and time with the following commands:
> GPS:INIT:DATE (date)
> GPS:INIT:POS (position)
> GPS:INIT:TIME (time)
>
>      I then setup the unit (inside, but with the GPS antenna near a
> window) and left it turned on overnight. However, no dice. The system
> does not display errors but won't track any satellites. Here is the
> results of a SYSTEM:STATUS? command:
>
> scpi > system:status?
> ------------------------------- Receiver Status
> -------------------------------
> SYNCHRONIZATION ........................................... [ Outputs
> Invalid ]
> SmartClock Mode ___________________________   Reference Outputs
> _______________
>     Locked                                     TFOM 9             FFOM     3
>     Recovery                                   1PPS TI  --
>     Holdover                                   HOLD THR 1.000 us
>  >> Power-up: GPS acquisition Holdover Uncertainty ____________
>                                                Predict  --
>
> ACQUISITION .............................................. [ GPS 1PPS
> Invalid ]
> Tracking: 0 ____   Not Tracking: 14 _______   Time
> ____________________________
>                     PRN  El  Az  PRN  El  Az   UTC 05:08:22 [?] 11 Oct 2018
>                     * 1  -- ---  *10  -- ---   GPS 1PPS Invalid: not
> tracking
>                     * 2  -- ---   16  35  50   ANT DLY  0 ns
>                     * 3  -- ---  *23  55 129   Position
> ________________________
>                     * 5  -- ---   26  10  41   MODE Survey:      0% complete
>                     * 6  -- ---   27  21  96 Suspended: track <4 sats
>                       7  57 267   30  25 257   INIT LAT N 47:42:01.770
>                     * 8  13 127                INIT LON W 122:16:26.770
>                       9  81 141                INIT HGT          +20.00
> m  (MSL)
> ELEV MASK 10 deg   *attempting to track
> HEALTH MONITOR .........................................................
> [ OK ]
> Self Test: OK    Int Pwr: OK   Oven Pwr: OK   OCXO: OK EFC: OK   GPS
> Rcv: OK
> scpi >
>
> Is there anything else I can try?
>
> Thanks in advance,
> Matthew D'Asaro
>
> On 10/07/2018 12:26 AM, Mark Sims wrote:
> > The 58503A needs a null-modem pinout serial cable to connect to a PC. The baud rate defaults to 9600:8:N:1
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