Akai VS-2EGN - Page 67

5-3 KEY SCAN
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Fig. 7-81 Key Scanning
Sepresed Fe | REW | stop | REC |PLAY | CUE |Review] | F-ON | F-OFE] EJECT] PAUSEFOUNZEN | owory
Mode cope| o1 | 02 | 03 | 0s | 06 | o7 | o8 oc | op | oo | 19 | oa 04
FUNCTION stor| —
OFF|
STD-BY 0 o | o ° °
FF 1 ° ° ° Oo} o ° °
REWIND pearl tre} o}|o ° °
STOP
STOP
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STOP REC «PLAY
pause,
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CUE/REVIEW : In VS-5, acceptance only from PLAY.
In VS-2, acceptance even from FF and
RWD.
© : Acceptable.
Character display: Corresponds to that mode.
Blank: Unacceptable.
64
Fig. 7-82 Key Acceptance Judgement Table
*1: Eject state or cassette-nonexistent state.
*2: Acceptable only when cassette tab is unbroken,
Service Manual VS-2EGN
Of eight O-port outputs (pin @- pin 6) of the front
processor, each output is brought to LOW level sequen-
tially. K input (K-port: pin @) ~ pin (9) is read. If
it is LOW, the microcomputer identifies which key is
depressed based on the data about which pin No. of O-
port has been made LOW and data about the pin No. of.
K-port which is at LOW level. 32 ms is required for a
single scan, The microcomputer judges that the key has
been depressed properly, if the key has been depressed
for two scans. (Chattering can be prevented) Only when
the REC key is depressed from the STOP state, REC is
not accepted even at the 9th scan unless the REC key
has been continuously depressed during that time, thus
preventing one touch record by accident,
Each time the SYSTEM key (newly provided in VS-2
EGN) is pressed, an “H”—» “L” or “L”=“H” signal is
sent out to the system switching microcomputer in the
servo PCB, through the connector P-34 from the front
processor R3 (pin 49).
Fig. 7-81 key scanning.