Akai AA-A35 - Page 12

5-1-5 Input Selector Analog Switch (TC9164N)
Controls the electronic potentiometer (TC9176P) and
the tone potentiometer (TC9156P).
(1) Serial Data Structure
The serial data is composed of 3 parallel bits that
include DATA, CK, and ST, and the numbers of serial
bits of the individual potentiometers have been made
as follows:
TC9164N > 14 bits
TC9176P > 20 bits
TC91S6P > 18 bits
Control lines DATA and CK for the TC9176P and
TC9156P have been made common with control lines
ST-WR and CE for A/D converter LC7910, because
A/D conversion and data transfers to the potentio-
meters will never occur simultaneously, and no
changes in the status of potentiometers will take
DATA(R70,91)
[Data Timing Schematic Diagram]
Pin @\
Pin @,@)
CKIR7I,92)
Pin ©.
ST(R72,73)
14/20/18 BIT
;
(2) Data Buffers
Fig. 5-3
Data buffers for the TC9146N are formed in RAMs
MFSRDO through MFSRD3, and those for the
TC9176P and TC9156P in RAMs MVSRDO through
MVSRD4. Their allocation charts are shown in Tables
place as long as no ST are issued. 5-1 to 5-3.
a) Buffers for the Input Selector Switch (TC9164N)
MFSRD3 MFSRD2 MFSRD1 MFSRDO
~ oN wa
2255/2828 % ge th
Pm Oo ze A me 8 ial
0 o 1 1 £0 1 1 )0 1 0 O | —> Fixed Data
ON OFF Table 5-1
Bits 2 and 3 of MFSRD1 will not be transmitted.
b) Buffers for the Master Potentiometer (TC9176P)
MVSRD4 MVSRD3 MVSRD2 MVSRD1 MVSRDO
LR 0 | 2 4 6 8 | 0 10 20 30 | 40 50 60 70 | C, Cy C3 Cy
0 0 0 O 1 | —> Fixed Data
Table 5-2
c) Buffers for the Tone Potentiometer (TC9156P)
MVSRD4 MVSRD3 MVSRD2 MVSRD1 MVSRDO
+5 +4 43 42 | +1 0 te 29 3-4 “5 LI R CG CG C3
0 0 1 1 0 I O | —>+ For BASS
0 0 1 1 1 0 O | —~+ For TREBLE
Table 5-3
SERVICE MANUAL AA-A35/L
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