Platinum Z5 CD, Руководство пользователя

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WARNING: Disconnect primary power prior to servicing.
Overall System Theory
4.5.1.2.1 Tap Switching Circuit Operation
The control signals for the SCRs are active high and come directly from the PS
Controller Board. They enter the “B” 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 Q28
which applies 10VB-SS, now called DRIVE_1, to R12 on the “B” side of the 48V
section. Interconnect cable J3 then connects the same signal to R25 on the “A” side
Rectifier Board 48V section.
NOTE:
The 10VB-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 10VB-SS forward biases diodes CR4, CR8 and CR12 on the “B” side and
CR13, CR17 and CR21 on the “A” side. This turns on the associated SCRs, Q4, Q8
and Q12 for the “B” side and Q13, Q17 and Q21 on the “A” side. Each of the SCR
anodes are tied to ground with the cathode connected through a 30 amp fuse to a tap
on one of the transformer secondaries. The “B” side is connected to L5, M5 and N5
with the “A” side connected to L4, M4 and N4 (see the Overall System Block
Diagram for these connections). Note that both the “A” and “B” side SCRs have
selected the same relative (lowest voltage) taps on each of the two transformer
secondaries.
4.5.1.2.2 PA Power Supply Soft-Start
Soft-Start is used to limit the surge current during transmitter turn on. The Soft Start
and PA Power Supply Discharge circuits are able to use the same resistor, R48 since
only one or the other will be active at any one time. A simplified diagram of the Soft
Start and PA Power Supply Discharge circuits in shown in Figure 4-8. The Soft-
Start control signal is active high and comes directly from the PS Controller Board,
via J4-8. A high SOFT START signal at J4-8 causes U2-12 to go low. This turns on
FET switch Q32 which then applies the 10VB-SS through R65 to CR28, CR29 and
CR30. This in turn activates SCRs Q34, Q35 and Q36. The three SCR outputs are