Sound Volume - Sharp Linytron C-1408T Serviceanleitung

(6) Display
(7)
The output signals from the digit pins D, and Dz and
those from the segment pins a to g are dynamically
combined together and so processed as to indicate
on the display which channel the unit is now tuning
in: the kinds of the channel No. display follow the
operation according to the key matrix 2.
In about 4 msec after the auto clear mode is finished,
it is from the digit pins D, and D2 that there are
generated clock signals at the intervals of about 8.2
msec one after another, each of the duty 43.75%.
These clock signals are to control the output signals
from the pins a to g in different ways to cause different
channel Nos. to be indicated on the display. The
channel No. indication is of 2 digits, and in the case of
its upper digit being zero, there is no display for this
digit.
Analog amount control
There sorts of analog amount (SOUND VOLUME,
COLOR and CONTRAST) are controlled by PWM
clock signals which are generated at the analog control
output pins S-VOL, COLOR and CONTRAST each
located on the IC (C1001): the analog amount of
SOUND VOLUME is variable in 48 steps and that of
either COLOR or CONTRAST is variable in 64 steps,
and generation of each clock signal is made at the
intervals of about 2.4 msec.
Actually for this analog amount control, such keys
as S-VOL UP, S-VOL DOWN, COLOR UP, COLOR
DOWN, CONTRAST UP and CONTRAST DOWN
are used, and as long as each of these keys is pushed, .
the relevant output is varied step by step, and it takes
about 6 seconds for the amount to be changed from
its minimum to its maximum and vire versa.
When the Norlization key is pushed, the S-VOL
amount is set at half its maximum and also the COLOR
and/or CONTRAST amount at half its maximum.
While the muting is kept on (with the MUTE key on),
if one of such keys as of S-VOL UP, S-VOL DOWN,
Normalization and POW ON/OFF is pushed on, the
muting is stopped. And in the case of pushing the
S-VOL UP ot S-VOL DOWN key, the sound volume
is first set to such level as it had been before the
MUTE key was pushed on and then is varied with
the pushing of the S-VOL UP or S-VOL DOWN key.
In the case of pushing the Normalization key, the
sound volume is always set at half its maximum.
The same analog output control as above is also availa-
ble by operating the keys on the remote control
transmitter.
As to each of CONTRAST and COLOR output, it is
at "low" level for the minimum analog amount and
at "high" level for the maximum analog amount.
On the other hand, as to S-VOL output, it is at "high"
level for the minimum and at "low" level for the
maximum: that is, it is kept at "high" level when the
muting is turned on.
(8
—
(9)
(10)
When the sound volume is at its lowest level, if the
S-VOL UP key is pushed, the volume increases by 16
steps at once, and thereafter it will rise up step by
step according to the push of that key.
MUTE key function
The MUTE key is of a toggle type, and the muting
turns on and off alternately every time it is pushed.
With the muting on, the analog control output signal
S-VOL becomes "high" level so that the sound volume
is set to its minimum level. With the muting off, the
sound volume is reset to such level as it had been
before the muting was turned on.
The same operation as above is also available by using
the MUTE key on the remote control transmitter.
POWER ON/OFF key function
The POWER ON/OFF key is of a toggle type, and the
power turns on and off alternately every time it is
pushed.
With the power turning on, the power on/off output
signal becomes "high" level, and then it is as men-
tioned in "(6) Last power on/off memory function"
that if the main switch is turned on later, that "high"
level signal causes the unit to tune in the channel which
has been selected for the last time: at this time, the
muting is turned off, S-VOL, COLOR and CONTRAST
'are reset to such levels as they had been before the
power on/off key was pushed on. With the power
turning off, the power on/off output signal becomes
"dow" level, and the display output signals a to g and
Eo to E, are all at "low" level. And the A-port output
signals A, to A3 and the B-port output signals Bo to
B, become "low" level, and the output signal from
pin S-VOL becomes "high" level and the output
signals from pins COLOR and CONTRAST remain
at the same level as before the power on/off key has
been pushed off. The output signal from pin D/A
becomes "'high'' level.
And with the power turning off, it is allowed for you
to perform the operations according to the key matrix;
but, it is on the remote control transmitter that its
power on/off key alone can be used, but not allowing
the use of the other keys on it.
Operation of the FT (+) and/or FT (—) key is effective
in any modes other than the channel presetting mode.
When the FT (+) or FT () key is pushed, AFT control
output signal becomes "low" level and the tuning
voltage starts to increase and decrease. And as long as'
the key is pushed, such increase or decrease continues
until the tuning voltage reaches its maximum or
minimum value.
When pushing the key is stopped, the information data
relevalent to the tuning voltage then available is written
into the EAROM: at the time, the AFT OFF data is
also written thereto.