350-Watt Digital VHF LB Transmitter
Chapter 4, Circuit Descriptions
DT325B, Rev. 0
4-1
Chapter 4
Circuit Descriptions
NOTE:
Information and drawings on the
Axciter Modulator Tray, the Upconverter
Module and the Downconverter Module
are contained in the separate Axciter
Manual.
4.1 (A4) Control Monitoring/Power
Supply Module, 220VAC
(1310835; Appendix C)
The Control Monitoring/Power Supply
Module Assembly contains (A1) a Power
Protection Board (1302837), (A2) a 790
Watt Switching Power Supply, (A3) a
System Controller Board (1310089),
(A4) a LCD w/Switches Board (1307977)
and (A5) a LCD Display.
AC Input to the Amplifier/Driver Chassis
Assembly
The AC input to the Amplifier/Driver
Chassis Assembly is connected from J1,
part of a fused entry module, located on
the rear of the chassis assembly to J50
on the Control Monitoring/Power Supply
Module. J50-10 is line #1 input, J50-8 is
earth ground and J50-9 is line #2 input.
The input AC connects to J1 on the Power
Protection Board where it is fuse
protected and connected back to J50, at
J50-11 AC Line #1 and J50-12 AC Line
#2, for distribution to the cooling Fan.
4.1.1 (A1) Power Protection Board
(1302837; Appendix C)
The input AC connects through J1 to two
10 Amp AC fuses F1 and F2. The AC
line #1 input connects from J1-1 to the
F1 fuse. The AC line #1 input after the
F1 fuse is split with one line connected
back to Jack J1 Pin 4, which becomes
the AC Line #1 to the Fan. The other
line of the split connects to J4. The AC
line #2 input connects from J1-3 to the
F2 fuse. The AC line #2 input after the
F2 fuse is split with one line connected
back to Jack J1 at Pin 5, which becomes
the AC Line #2 to the Fan. The other
line of the split connects to J2. J1-2 is
the earth ground input for the AC and
connects to J3.
Three 150-VAC, for 115 VAC input, or
three 275-VAC, for 230 VAC input, MOVs
are connected to the input AC for
protection. One connects from each AC
line to ground and one connects across
the two lines. VR1 connects from J4 to
J2, VR2 connects from J4 to J3 and VR3
connects from J2 to J3.
+12 VDC Circuits
+12 VDC from the Switching Power
Supply Assembly connects to J6 on the
board. The +12 VDC is divided into four
separate circuits each with a 3 amp self
resetting fuse, PS3, PS4, PS5 and PS6.
The polyswitch resettable fuses may
open on a current as low as 2.43 Amps
at 50°C, 3 Amps at 25°C or 3.3 Amps at
0°C. They definitely will open when the
current is 4.86 Amps at 50°C, 6 Amps
at 25°C or 6.6 Amps at 0°C.
PS3 protects the +12 VDC 2 Amp
circuits for the System Controller, the
Amplifier Controller and the Spare Slot
through J62 pins 7, 8, 9 and 10. If this
circuit is operational, the Green LED
DS3, mounted on the board, will be lit.
PS4 protects the +12 VDC 2 Amp
circuits for the Modulator and the IF
Processor through J62 pins 13, 14, 15
and 16. If this circuit is operational, the
Green LED DS4, mounted on the board,
will be lit
PS5 protects the +12 VDC 2 Amp
circuits for the Upconverter through J62
pins 17, 18, 19 and 20. If this circuit is
operational, the Green LED DS5,
mounted on the board, will be lit
