Technics RS-TR474

pe mechanism
DECK 1:10701 @ or W701 © ® .
DECK 2: 10701 @
es the voltage input to AD
ange as each operating switch
pressed ?
NO
es from OV
an Power,
.. Play, FF
ns are
order,
ses from
0.4V
en Stop, F.
ay buttons
that order.
set is
ther
stems.
anism 1, be
ne counter
]
eck continuity of switches
1ose voltage does not change
1en pressed.
case of failure, replace with
w switches.
i
ty
i
Tape mechanism 2
Tape mechanism 1
Does the voltage at
microprocessor pin 64 change
when S801 and S802 of the
mechanism PCB (or the leaf
switch of the mechanism) are
forced into the on positions ?
Does the voltage at |
microprocessor pin 2 change
when S803 and $804 of the
mechanism PCB (or the CrO, and
Metal switches of the :
mechanism) are forced into the
on positions (A D1 D2) ?
YES |
Connection check for Connector
switch failure.
Soldering checks
Do pulses develop at
microprocessor pins 25, 27 and
28 when the mode switch is
pressed on ?
Do pulses develop at
microprocessor pins 26, 27 and
28 when the mode switch is
pressed on ?
Microprocessor failure.
Does the voltage at
microprocessor pin 1 change
when switch of the mechanism
(MODE, Revers REC INH and
HALF SW) are forced into the on
positions.
Do similar pulses develop at CN1
pins 4, 5 and 6 of mechanism 1
when the mode switch is pressed
on?
Connection checks for
connectors, FFC cable,
soldering, etc.
Are pulses applied to terminals
13, 15 and 16 of C801 when the
mode switch is pressed on ?
YES |
Are pulses applied to terminals
13, 15 and 16 of IC801 when the
mode switch is pressed on ?
Pattern and soldering checks.
Plunger failure. |
Does
the
plunger
instantly
pullin
|
NO
_
|
Q803,
Q804,
D801,
D806,
D802,
Play button is pressed ?
D804 failure.
1C801 or IC802 failure.
Does the plunger remain pulled in
during FF/REW operations ? NO
YES
Belt has come off.
Reel motor failure.
1C801 or 1C802 failure.
oon ee
Audio circuit
Does the voltage at 10152 pin 12
change when in the REC and
Stop modes ?
16152 is normal.
Microprocessor failure.
Connection checks for
connectors, FFC cable.
Do pulses develop at
microprocessor pins 20 and 21
when REC mode changes to Stop
mode
Do pulses develop at 1C152 pins
2 and 3 in the REC and Stop
modes ?
10152 failure.
As shown above, check the voltage at each pin of !1C152 for the following:
@® Equalizer 120p1s/70ps change.
@ Dubbing seed does not change.
@®
Erase
current
does
not
change
between
the
CrO2
and
Normal/Metal
tape.
(Erase current for CrO2 and Normal tape is the same.)
@® Deck 1 and deck 2 produces no change.
® Dolby off, B and C produces no change.
® REC and Play produces no change.
@ Auto REC mute does not operate.
| RS-TR474