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The LCD Key PCB Module
The LCD Key PCB module consists of U701
(EM78P468NAQ) which is an MCU controlling
IC401 in the CD servo PCB module via CD_STB
(pin 38), CD_ACK (pin 39), and CD_DATA (pin 40).
It also drives the LCD display directly via pins 1 thru
19, receives an MCU RESET signal at pin 25 in
synchronization with IC401 from the CD servo PCB
module, and interfaces directly with the six keys
providing the CD functions STOP, PLAY/PAUSE,
EJECT, FF, RW, and MODE.
The Input PCB Module
The input PCB provides both channels 1 and 2 with
XLR and ¼" phone jacks, and channel 3 with stereo
RCA jacks and a ¼" phone jack. It also provides
the AUX SEND, AUX RET, and FOOT SWITCH in-
puts. The signals from the XLR and ¼" jacks are
amplified (mic mode by +30dB) or buffered (line
mode by 0 dB) and then fed to the Mixer PCB mod-
ule.
The Mixer PCB module
The Mixer PCB module receives inputs from chan-
nels 1-3 and the CD servo PCB module. For each
channel it provides the following control functions.
1. LEVEL
2. EQ LOW
3. EQ HIGH
4. REV/AUX
5. PAN/BAL
PASSPORT
(This is the model name for warranty claims)
These signals from each channel are mixed at the
inputs of U209A and U209B. From here they are
controlled by U210A and U210B for Master Volume
Left and Right, and then by U211A and U211B for
System EQ Left and Right. Finally the left and right
channel signals are buffered by U212A and U212B
respectively before they go to the inputs of the
class-D amplifier PCB module. The REV/AUX sig-
nals from each channel are sent to pin 4 of
connector CN210, which is the input to the DSP
Reverb PCB module, via U208A and U208B. The
output signal from the DSP Reverb PCB module is
sent to pin 6 of connector CN210. The level of Re-
verb can be controlled by MASTER REV (VR224A).
The Class-D Amplifier PCB Module
The class-D amplifier TDA8920B is a single
42VDC-supplied bridge configured to deliver 75W
output power for both the left and right channels at
THD < 1% into an 8-ohm load.
The DSP Reverb PCB Module
The DSP Reverb PCB module receives the input
REV/AUX signals at pin 4 of connector CN401. The
DSP Reverb's IC's consist of U404 (AL1101 ADC),
U405 (AL1201 DAC), and U406 (AL3201B). The
outputs from U405 are fed to U402B and then buff-
ered by U402A before feeding back to pin 6 of CN
401.
®
PD-150 PLUS
7
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