This page documents the large LED sign acquired by Hackeriet, gifted by pere and asle.

This is an Ericsson-branded, Alpha-American / Adaptive Micro Systems 4200C LED sign.

It is a programmable LED display commonly used for transit, public information, or industrial messaging systems.

• Model: 4200C
• Manufacture Date: 2004-04-08
• Power: 100–240V AC, 50/60Hz, 1.5A
• Status: Fully operational, displaying test message on boot. Unknown operational method.
• For indoor use only.

The device seemingly runs a custom firmware, the label on the epromm is “4200c CUST 1018-6008e”, and it displays CUST during boot.

The sign has a RJ-style modular port on the back panel with:

• RS-232 IN
• RS-485 IN
• RS-485 OUT

It also has an IR sensor hidden behind a red sticker, visible when removing a panel.

A small dongle with resistors was included, likely serving as a RS-485 termination and bias dongle.

The sign probably uses the Alpha Sign Communications Protocol, which is:

• A structured serial protocol using STX/ETX framed packets.
• Allows sending:
  • Text messages
  • Control commands (clear, brightness, modes)
  • Time-based messages
• Multiple signs can be connected via a RS-485 network

Suggestion for initial connection (untested):

• Interface: RS-232 IN (single device)
• Baud rate: 9600 or 19200
• Data bits: 8
• Parity: None
• Stop bits: 1
• Flow control: None

RJ-12 Pinouts, from left, clip down

1. ground → GND TTL / db9 pin 5
2. RS485 (+)
3. RXD → TXD TTL / db9 pin 3
4. TXD → RXD TTL / db9 pin 2
5. RS485 (-)
6. +5V (200ma max)

It seems that normal configuration of the sign is done over IR with a remote control or with an IR message loader attached via the RJ-12 connector.

The a quick look at the usual resources do not appear to have a capture of the remote.

• LIRC remote configurations
• flipper IRDB

• Alpha American Technical Manuals
• Alpha® Sign Communications Protocol
• alpha - cables adapters interfaces