Recently brought home 58503, cheap at industrial auction.

The power supply was faulty, seriously burnt  pcb area around
the line input circuit. Fixed that and put back together.

The psu runs very hot in the 58503, no fan cooling, so not
surprised it eventually failed. There is a design fault,
in that there is wirewound dropping resistor at the line input,
one assumes to lose volts to support the full range of input
line voltages. Perhaps originally a 115v psu, but hacked to
support a higher range of voltages. Anyway, that resistor
gets >100C and is placed right next to the input reservoir
capacitor. To improve reliability, bought in a TO220 film
resistor, mounted to the side of the case, which takes some of
the heat away from the input cap. The psu runs quite a  bit
cooler overall now. Long term, will probably find a more modern
equivalent psu, as the original is marginal, design wise...

Chris

Thought the following might be of interest:

 Symmetricom Netclock/IRIG 9383. Modify for GPS Input
 ----------------------------------------------------

 Modification Notes: Chris Quayle, 03-September 2023
 ---------------------------------------------------

• From a photo, able to identify the gps module in use,
  a Trimble Resolution T

• Replace IRIG card with Trimble Resolution T gps module
  (See below)

• Firmware is on 256 Mb CF card, Vile Linux 2.6.15 Ext3
  file system

• Card into laptop, Suse Linux 11.4 here

  • image the card
    "dd if=... of=9383.img bs=1m"
  • Mount on /mnt
  • chroot to /mnt, to reset root password
  • Rewite edited image using dd to 512mb card, as
    original is slightly greater than 256mb. Verify
    it still boots and reaches login prompt.

• Reboot system, login as root via internal
  keyboard and vga port

• In /etc/ssh/sshd_config
  PermitRootLogin yes

• Reboot, login as root from remote, "ssh root@192.9.200.170"

• Dig around the system, (no 'more' on this box :(, then:

• cd /etc/ntp

• cat ntp.conf, looks ok
  restrict 127.0.0.1
  restrict -4 default noquery nomodify
  restrict -6 default noquery nomodify
  keys /etc/ntp/keys/ntp.keys
  controlkey 65533
  requestkey 65534
  trustedkey 65533 65534
  server 127.127.1.0  Clock (LOCAL)
  fudge 127.127.1.0 stratum 15
  enable pps
  server 127.127.45.0 prefer  PCI
  server 127.127.22.0 minpoll 4 maxpoll 4Discipline
  fudge 127.127.22.0 stratum 0
  keysdir /etc/ntp/keys/
  driftfile /etc/ntp/ntp.drift
  logfile /opt/log/ntp.log
  statsdir /opt/log/ntpstats/
  statistics loopstats peerstats clockstats
  filegen loopstats  file loopstats  type day enable
  filegen peerstats  file peerstats  type day enable
  filegen clockstats file clockstats type day enable

• login to command line interface
  cd /opt/usr/bin
  cli

  Welcome to the Spectracom Command Line Interface
  (c)Copyright Spectracom Corporation 2006

• root@192.9.200.170 > help
  Command line interface (CLI) help.
  Type 'help cmd' for a detailed help on the 'cmd' command.
  The following are the available commands.
  time    - time
  reboot  - reboot
  halt    - halt
  log      - log COMMAND OBJECT [ HANDLE ]
  option  - option COMMAND [OPTION | PRODUCT] [VALUE]
  ltc      - ltc COMMAND [INDEX | NAME] [...]
  clean    - clean [restart | halt]
  net      - net COMMAND [Arguments]
  disc    - disc COMMAND ARG
  sys      - sys COMMAND [Arguments]
  photo    - photo COMMAND [Arguments]
  ser      - ser COMMAND SERIAL [Arguments]
  rem      - rem COMMAND REMOTE [Arguments]
  sernum  - sernum COMMAND
  irig    - irig COMMAND ARG
  show    - show [on | off]
  frq      - frq COMMAND INDEX [Arguments]

• root@192.9.200.170 > option display
  Product Name: 9383

     Security               : on
     Modem                  : off
     Serial Port 1          : on
     Serial Port 2          : on
     Remote Port 1          : on
     Remote Port 2          : on
     IRIG Output            : on
     Front Panel Display    : on
     Relays                 : on
     Oscillator Disciplining: on
     10 MHz Frequency Output: on
     IRIG Input             : on
     Oscillator             : TCXO
     Gps Receiver           : NONE
     Board                  : NONE
  

• Try setting defaults ???

• root@192.9.200.170 > option default
  Default options restored for: 9383

• root@192.9.200.170 > option display
  Product Name: 9383

     Security               : on
     Modem                  : off
     Serial Port 1          : on
     Serial Port 2          : on
     Remote Port 1          : on
     Remote Port 2          : on
     IRIG Output            : on
     Front Panel Display    : on
     Relays                 : on
     Oscillator Disciplining: on
     10 MHz Frequency Output: on
     IRIG Input             : off
     Oscillator             : TCXO
     Gps Receiver           : Trimble Resolution T
     Board                  : NONE
  

Looks like default config is for a gps  reference,
not IRIG

• GPS Modules

  Dump the application: od -S 5 usr/bin/hs92XX
  looking for gps module references, we find:

  Motorola Oncore M12+ Timing
  Motorola M12M Timing
  Motorola M12M Navigation
  Trimble Resolution T
  Trimble Force-22 SAASM

  So, looks like quite a choice.

Had thought the IRIG and GPS types might need a
different firmware load, but there were entries
early on in log files which suggested an initial
default to a gps install, with IRIG being an
option set at build time. Anyway was able to
identify the GPS module in use from pics from
another time-nuts member, with thanks.
Found online and all seems to work, with good
timing accuracy, though suspect would be better
with a more stable oscillator. Good enough for ntp
use though.

A useful addition to the time & frequency
collection...

Chris