Akai GX 77 Service Manual 1
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Extracted text from Akai GX 77 Service Manual 1 (Ocr-read)
Page 1
Olf-ļ¬/ \
STEREO TAPE DECK
MODEL GX- 7 7
THIS MANUAL IS ALSO APPLICABLE TO BOTH SILVER
AND BLACK PANEL MODELS
SECTION I SERVICE MANUAL .................... 3
SECTION 2 PARTS LIST .......................... 45
SECTION 3 SCHEMATIC DIAGRAM ................ 65
Page 2
SAFETY INSTRUCTIONS
SAFETY CHECK AFTER SERVICING
Conļ¬rm the speciļ¬ed insulation resistance between power cord plug prongs and externally exposed parts ofthe set is
greater than 10 Mohms, but for equipment with external antenna terminals (tuner, receiver, etc.) and is intended for
or I, speciļ¬ed insulation resistance should be more than 2.2 Mohms (ground terminals, microphone jacks.
headphone jacks. line-in-out jacks etc.)
PRECAUTIONS DURING SERVICING
l.
owso
Parts identiļ¬ed by the A symbol parts are critical for safety.
Replace only with parts number speciļ¬ed.
In addition to safety, other parts and assemblies are speciļ¬ed for conformance with such regulations as those
applying to spurious radiation. These must also be replaced only with speciļ¬ed replacements.
Examples: RF converters, tuner units, antenna selector switches. RF cables, noise blocking capacitors, noise
blocking ļ¬lters. etc.
Use specified internal wiring. Note especially:
1) Wires covered with PVC tubing
2) Double insulated wires
3) High voltage leads
Use speciļ¬ed insulating materials for hazardous live parts. Note especially:
1) Insulation Tape
2) PVC tubing
3) Spacers (Insulating Barriers)
4) Insulation sheets for transistors
When replacing AC primary side components (transformers, power cords, noise blocking capacitors, etc). wrap
ends of wires securely about the terminals before soldering
D D
Observe that wires do not contact heat producing parts (heatsinks. oxide metal ļ¬lm resistors, fusible resistors. etclr
Check that replaced wires do not contact sharp edged or pointed parts.
Also check areas surrounding repaired locations.
Use care that foreign objects (screws, solder droplets. etc.) do not remain inside the set.
Page 23
LINKED WITH COUNTER
LAMP PCB
Ā£22 DETECTION ROLLER
DETECTION
HOLDER
DETECTION PCB
TR2 (PHOTO TRANSISTOR) TRI (PHOTO TRANSISTOR)
- 4. '2.5
.e Smsec-aem sec-)I
TR2
TAPE PULSE
u d)
ROLLER @
IC-I
(UP/DOWN)
lC-I
(TAPE PULSE) '
W
lC-I
__F
m-.. __|
3) COUNTER Operation (Refer to Figs. 25, 26)
The output of TRl is inputted into ICl D12 Ā®>
after waveform shaping in the Schmitt Circuit of
TR18 and TRI9. The output of TR2 is inputted
into [Cl (33) after waveform shaping in TRIS to
TR17, and depending on the phase relation, it
conducts UP or DOWN count. (For the waveform
of TRIS-l7, see auto-stop circuit).
Input waveforms of [Cl (ID, (ID (Counter Circuit)
Fig. 25
FF MODE
(TYPICAL)
UP COUNT
RWD
(TYPICAL)
00w N cou NT
Fig. 26
23