Those are NICE displays. So, you have a total of 20 boards x 4 per board = 80 LED displays ? Someone went to a lot of effort to wire-wrap those instead of making a PCB.
The logic is very simple: MC14511 BDC-to-7 segment decoder, two 74161 shift registers. As Bill said, you should be able to reverse-engineer this fairly easily, and then you would need just a few simple signals to control the shift-registers (clock, data, clear). You could even use some pushbutton switches to test it out; just be sure to de-bounce the clock signal. The data and clear signals dont need de-bouncing. On Thursday, December 31, 2020 at 2:19:22 PM UTC-8 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 [email protected]. >> > 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 [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/274a0079-a15c-42c2-9705-665993d613c9n%40googlegroups.com.
