Specifications
42
The following table describes the conditions of the LED indicators and if a problem is indicated, the 
solutions: 
Table 5 
Trouble LED Indicators 
Trouble LED  LED Condition “ON”  Problem 
Solution 
SPLITTER 
MISMATCH 
LED Indicator ON when all SP4-APS CLASS 
SW2 switch are not set the same. 
Check the CLASS SW2 
switch on all SP4-APS 
splitters and set them all as 
CLASS “A” or CLASS “B” 
as applicable. 
Use the SP4 Telzone 
Programmer software on the 
host computer to determine 
which SP4-APS splitter(s) are 
set to the wrong “Class of 
wiring”.
ON 
RS485 COMM LOSS 
1. RS485 Connection to an SP4-APS is 
inoperative. The “RS485 COMM LOSS” LED 
indicator will BLINK a pattern indicating the 
ordered location of the inoperative splitter 
connection and above. All zones beyond the 
inoperative connection may not be able to be 
paged. 
2. An SP4-APS Power Loss: Green POWER LED 
will be OFF on the SP4-APS. RS485 COMM 
LOSS LED will BLINK the number of times 
needed to identify the ordered location of the 
inoperative SP4-APS splitters. All zones on the 
SP4-APS splitter which has lost power will pass 
any audio even if the SP4-TZC requests the zone 
to be disconnected. All other splitters will function 
normally. 
1. Check the wiring. 
2. Check 24VDC power to the 
SP4-APS splitter. 










