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 shows the flow of the playback signals, and 

 shows the timing of the signals during playback. The

playback RF signals from heads A and B are input to the RF amplifier (IC1), the PB amplifier output is switched at a
timing of the switching pulse shown in the 

, and input to Pin #¶ (RFDT) of DAT DSP (IC503) from Pin 1

through the PB RF buffer (Q521). Extraction of the playback clock and synchronization of the playback data are carried
out based on the playback RF signal (RFDT) in the digital PLL (DPLL) circuit inside the DAT DSP. In the playback
system block, 10-8 demodulation and deinterleave different from that during recording, and error detection, error
correction, etc. are performed, and the audio data is transmitted to the selector (IC511) from Pin &¶ (DADT). At the same
time, the sub code data, etc. are transmitted from Pin @∞ (SDSO) to the main microprocessor (IC501).
During playback, Pin !§ of the main microprocessor (XREC/PB) becomes “H”, and the audio data input to Pins !™ and
!£ of the selector are output at the timings shown in 

 from Pin 9 to the audio meter circuit (IC702), D/A

converter (IC314) with built-in digital filter, and the modulation circuit for digital audio output (TX) inside the DAT
DSP. In the D/A converter, after signal processing such as filter calculation, etc. is performed by the digital filter, D/A
conversion is performed and the signals are output to the respective MIX amplifiers (IC101, IC201) in the later stage.

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The PCM-2800 is equipped with heads A’ and B’ (following heads) used for playback only and for monitoring, besides
heads A and B (leading heads) composed with four heads for normal recording/playback only, which enable
simultaneous monitoring and playback [RAW (Read After Write] during recording. 

 shows the block diagram

of the signal circuit and 

 shows the main waveform timings during recording and playback.

Heads A-B, RF (REC/PB) amplifier (IC1), and master DAT DSP (IC503) are used during recording and normal
playback, while heads A’ and B’, RF (PB) amplifier (IC51), and slave DAT DSP (IC803) are used for simultaneous
monitoring and playback during recording.
During recording, the monitor selector (IC805) is switched according to the INPUT/REPRO switching signal (H :
INPUT, L : REPRO) output from Pin !¶ (XREPRO) of the main microprocessor (IC501) according to the operations of
the INPUT monitor switch on the front panel to select the INPUT side of the analog/digital input or the REPRO side
from the monitor head. During playback, “H” is output from Pin ! ¶  of the main microprocessor regardless of the
selection of the INPUT monitor switch, the selector (IC511) is set to the playback mode by the recording/playback
switching signal (H : PB, L : REC) from Pin !§ (XREC/PB) of the main microprocessor and the playback signal of the
master DAT DSP is output.
As shown by the waveform timings of each mode in 

, recording and normal playback are performed in the first

half of channels A and B of SWP, while during simultaneous monitoring and playback during recording, the playback
signal from heads A’ and B’ is output in the latter half of the SWP because heads A’ and B’ and heads A and B are
attached at an angle differing by 90˚. During after recording such as additional writing of the start ID and renumbering,
because only the sub data area is set to the recording mode and rewriting is performed, the playback RF waveform
without this area will be output.