I.S. INTERCOM
20-278-12
TYPE ABMA4 USER MANUAL
17 OF 21
Issue: 05
Figure 19: V-Line break in the middle
Figure 20: V-Line break at the end
The V-Line carries the PSA tones and a break it this line means that you will only get a ‘hee’ sound and the
PSA controller will not get a confirmation. This should be your primary method of determining if the system
OK or not.
The example above shows how the ABMA4 graphical display can help determine where the V-Line break
has occurred. Note this is the most difficult to detect and analyse as the signal may not reach the end
ABMA4 unit. The easiest analysis would involve just a walk down the system cable and a look at each
generic display (i.e. wakeup each unit with a menu key press) to work out where the V-Line tick (
√
) changes
to a cross (
×
). Then the break will occur between these units. Unfortunately, because of the nature of system
cable and installation history, how each ABMA4 interprets the V-Line signal after the cable break is
indeterminate. If a cable is a ‘clean’ electrical (i.e. good shielding and correctly wired) then units after the V-
Line break will not display any PSA Loop status. They will not have updated their display and the PSA Loop
will have blanks (see figures on the end ABMA4 in figures 18 and 19).
