I would suggest that these were never actually used as clocks, due to their somewhat homebrew look. I suggest they were weighbridge / scale displays which may of been constructed to give a large readout, driven from the aux port on a scale unit. Would make sense for a postal service to have many of those for vans loading up rather than lots of clocks...
On Saturday, 2 January 2021 at 15:35:06 UTC Jeffry P wrote: > I can find lots of clock circuits that are for lower voltage LEDs, but > these LEDs are 12v. > > On Thursday, December 31, 2020 at 4:19:22 PM UTC-6 Bill Stanley wrote: > >> Correct, these are a differential receiver to receive the serial (BCD) >> information, 2x8 shift registers to convert to parallel BCD and 4 BCD to >> seven segment LED drivers. >> >> With a bit of sleuthing, the schematic can be reverse engineered, reverse >> engineer the serial format and build or use a COTS CPU like Pi to display >> anything you wish. >> The power supply connector also probably has the serial data (look for >> wires going to the AM26LS32). Somewhere there will be a connection to >> inject that serial stream. >> >> >> -Bill- >> >> >> On Thursday, December 31, 2020 at 1:30:17 PM UTC-8 bani wrote: >> >>> These are not standalone clock displays. They are driven by an external >>> controller over serial. If the controller is not integrated into the >>> PSU, >>> then you are missing the external controller module. >>> >>> Personally I would just design a completely new clock using the LEDs. >>> >>> -Dan >>> >>> On Thu, 31 Dec 2020, Jeffry P wrote: >>> >>> > I purchased a clock display system from a USPS auction about 20 years >>> ago >>> > and recently rediscovered it in my storeroom. There are 20 displays >>> and a >>> > power supply. The displays were housed in a metal enclosure that has a >>> > window cutout for the LEDs. The window had a piece of red colored film >>> and >>> > the LEDs were behind. When I plug the power supply in it will light >>> all 0's >>> > and a decimal point (as seen in photos), but will not start keeping >>> time. >>> > I'm willing to send one of these boards( at my expense) to someone who >>> can >>> > help me get the thing keeping time again. I've attached a few photos >>> with >>> > descriptions of chips that are on the board and voltages measured at >>> the >>> > power supply connector. >>> > >>> > Thank you, Jeffry >>> > >>> > >>> > -- >>> > You received this message because you are subscribed to the Google >>> Groups "neonixie-l" group. >>> > To unsubscribe from this group and stop receiving emails from it, send >>> an email to neonixie-l+...@googlegroups.com. >>> > To view this discussion on the web, visit >>> https://groups.google.com/d/msgid/neonixie-l/85636c40-6036-40b9-9426-24310206c979n%40googlegroups.com. >>> >>> >>> > >>> >> -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/74152439-45eb-43c7-98e4-6ad5f3456e8fn%40googlegroups.com.
