Acom 03AT Operating Manual page 20

Should the AC line fuse blow, most likely there is a short circuit in the 24VAC-power cable or its connector to the
remote unit (it could be also a power-supply problem in either RCU or remote unit).
b) Besides the AC line fuse, there are four more fuses located in the remote unit. Two of the fuses are located on the
"Power Supply" PCB (marked F1 & F2 on the PCB – see fig.2-6). They are connected in series to the (24VAC/3A)
power-supply input of the remote unit. These fuses must be of the slow blow type too (antisurge, tardy or traege),
marked T or L), but for 3,15А nominal current. These are available from Farnell, cat.nr. 665-113 or from DIGI-KEY,
cat.nr. F980-ND.
Should the "Power Supply" fuses blow in the remote unit, most likely there is a short circuit in the relay-coils
supplying circuit - the Control-to-Coils cable harness (it could be also a power-supply problem in the proper Power
Supply PCB).
c) The last two fuses in the remote unit are located on the "RF Sensor" PCB that is installed under a separate
screen, located on the side closely to the RF input connector (look at the vertical cover at the left corner on fig.2-2).
To access these two fuses you have to unscrew all 8 screws M3x8mm (fig.2-2,i) and to remove this screen. You will
see the PCB "RF Sensor" under the screen with two fuses F1 & F2 on it (see fig.5-2).
Fig.5-2 Fuses on the PCB "RF Sensor".
The fuse F1 on the "RF Sensor" PCB must be of the ultra-rapid type or at least fast (quick blow or flink), marked FF
or at least with one F). It is for 2A nominal current (when marked with only one F, it should be for 1.8A). The proper
model could be supplied by Farnell, cat.nr. 532-782.
The fuse F2 on the "RF Sensor" PCB must be of the slow blow type (antisurge, tardy or traege), marked T or L), for
400mA nominal current. It is available from Farnell, cat. nr. 898-880.
Should either F1 or F2 on the PCB "RF Sensor" blow, most likely a too high power has been applied to the AATU
input (in excess of 150W) for tuning or SWR check. This can happen at operator's mistake and any casual protection
trip omission, respectively any control problem.
If the AATU still does not work after you have replaced the fuses, we recommend that the repair be accomplished by
trained personnel – contact your dealer or ACOM directly (see S.1-2).
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