What is the Difference between the Beige and Black GR2400 DTC / Green or Blue Screen
There are 2 versions of the GR2400 DTC and both versions can be found with a black case. Only the current version will be found with a green or blue screen. Both versions are interchangeable
And will work on any GR2400 or GR1400 system.
The main difference between and early DTC and the current is the modem connection the early DTC uses RS232 protocol for the modem and has an RJ11 connection and the modems take a separate power supply, while the current DTC uses TTL protocol and has a 4 wire connector the DTC powers the modem. The modems are not interchangeable so if an early DTC is being replaced with a current DTC then the modem needs to be replaced.
Another difference is the position of the contrast button early DTC it is on the bottom and current DTC it is on the face.
Contrast Button On Bottom
RS-2324 RJ-11 Modem Connection and RJ-45 DTC Connection
4 Pin Modem Connection and RJ-45 DTC Connection
You may find and early DTC with a black case but all of the DTC with a Blue screen are current.