4-26
888-2406-002
WARNING: Disconnect primary power prior to servicing.
Overall System Theory
secondary turns in circuit and will therefore give the lowest DC output voltage. This
means that the taps which are furthest from the center will give the highest DC
output voltage due to more active turns in the secondary.
4.5.2.2 Rectifier Board Circuit Description
Refer to the Rectifier Board schematic for the following. The Rectifier Boards
perform three primary functions:
•
Dynamic secondary tap switching using SCRs, to maintain a relatively constant
supply voltage and thus maintain constant transmitter power output despite fluc-
tuations in the AC line voltage. It also allows the controller to optimize transmit-
ter efficiency by selecting the best power supply voltage within its limited range
of about 6 volts.
•
PA Power Supply Soft-Start.
•
PA Power supply Discharge.
4.5.2.2.1 Tap Switching Circuit Operation
The control signals for the SCRs are active high and come directly from the PS
Controller Board. They enter the Rectifier Board at:
•
J4-1 - DRIVER 1 (activates SCRs for 48V tap)
•
J4-3 - DRIVER 2 (activates SCRs for 50V tap)
•
J4-5 - DRIVER 3 (activates SCRs for 52V tap)
•
J4-7 - DRIVER 4 (activates SCRs for 54V tap)
NOTE:
The circuit for the 48V tap will be explained here as the other three are identi-
cal, but are attached to different transformer taps.
The DRIVE_1 signal is used to activate the 48Vdc tap on T1 and T2 secondaries.
When active (HIGH) it causes the output of U2-17 to go low. This turns on Q1
which applies 20VB-SS, now called DRIVE_1, to R16.
NOTE:
The 20VB-SS (SS = Soft Start) will only be present if the DISCHARGE sig-
nal at J4-6 is inactive. See PA Power Supply Discharge later in this section for
more information.
The 20VB-SS forward biases diodes CR3, and CR4. This turns on the associated
SCRs, CR4 and CR8 on each power supply. Each of the SCR anodes are tied to
ground with the cathode connected through a 100 amp fuse to a tap on one of the
Summary of Contents for Platinum Z2 CD
Page 4: ...888 2406 002 WARNING Disconnect primary power prior to servicing ...
Page 6: ...888 2406 002 WARNING Disconnect primary power prior to servicing ...
Page 8: ...888 2406 002 WARNING Disconnect primary power prior to servicing ...
Page 10: ...888 2406 002 WARNING Disconnect primary power prior to servicing ...
Page 70: ...3 14 888 2406 002 WARNING Disconnect primary power prior to servicing Operator Guide ...
Page 130: ...4 60 888 2406 002 WARNING Disconnect primary power prior to servicing Overall System Theory ...
Page 194: ...6 38 888 2406 002 WARNING Disconnect primary power prior to servicing Troubleshooting ...
Page 196: ...7 2 888 2406 002 WARNING Disconnect primary power prior to servicing Parts List ...
