If using an M3U-series tester, use CB25 when regularly testing cables longer than 10 ft (3m), when testing cables with a large surface area shield or conductor, or when working in a high static environment to guard your M3U tester against damage from electrostatic discharge. On each board, 64 transient suppressor diodes especially designed for fast switching divert any overvoltages to ground before damage to tester electronics can occur. The CB25 mounts to the the control module tester like any CB board and is physically secured with supplied stainless steel thumbscrews. Attach your test CB boards directly to CB25 as shown in the 2nd photo below. Required for CableEye M3U series models only. Use CB25s on the control module, and the CB25X variant (Item 755X) on expansion modules.
NOTE: Once installed, a) calibrate the system, b) do not remove, not even when shipping the system to us for service.
2 Set of two boards with ground bypass wire, thumbscrews, and setup instructions