Akai GX-77 Service Manual

TR2 TRI
TAPE PULSE UP/DOWN
e) g \yP
LINKED WITH COUNTER ROLLER (0)
Poown
DOWN
TR2 TR; TRZ TR;
(RRA
DETECTION PCB
TR2 (PHOTO TRANSISTOR) TRI (PHOTO TRANSISTOR)
Fig. 25
1
r<—
4.5m
sec
><
2.5
>|
ee
Ic-1
(TYPICAL)
(UP/DOWN)
UP COUNT
1c-1
|
|
|
|
|
TAPE PULS
( E LSE) —) Le
Im sec
RwO
(TYPICAL)
1C-1
|
|
|
|
|
DOWN COUNT
ic—1
|
|
|
|
|
Fig. 26
3) COUNTER Operation (Refer to Figs. 25, 26)
The output of TRI is inputted into IC1 D12 @
after waveform shaping in the Schmitt Circuit of
TRI18 and TR19. The output of TR2 is inputted
into IC1 @ after waveform shaping in TR15 to
TRI7, and depending on the phase relation, it
conducts UP or DOWN count. (For the waveform
of TR15-17, see auto-stop circuit).
Input waveforms of IC1 @), @ (Counter Circuit)
23

Akai GX-77 Specifications

General

Track System	4-track, 2-channel stereo
Tape Speed	3 3/4 ips, 7 1/2 ips
Wow and Flutter	0.03% (19 cm/s)
Heads	3
Motors	3
Dimensions	440 x 244 x 358mm
Inputs	Line input (RCA)
Outputs	Line, Headphones