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9.5 ILLUMINATION AND DISPLAY CIRCUIT
a. Illumination for Each Button
__
ILMI +B (14.2V) is fed from power amplifier (eg. GM-A120)
to this circuit. The +B goes to the LEDs in the buttons via
resistors. The parallel connection of the resistors on the +B
line is to increase the power capacity explained in ''9.2 Power
Supply Circuit.''
b. Lamp in the Door
The door lamp is switched on by the Door Sensor (S26).
When the door opens, $26 turns off and Q1 and Q3 turn
on. Acc +B is fed to the lamp and turns it on.
c. TAPE/TUNER Display
When Q6 (TAPE) or Q24 (TUNER) turns on, Acc +B is fed
to Q30 via D19-1 or D19-2 and R90. Q30 turns on. Q26 —
Q29 turn on. Then, +B is fed to the TAPE or TUNER LED
Array. PD4050B
#15 (SO) puts out data for indicating TAPE
or TUNER and feeds them to PD7005
#2 (DATA). When
PD7005 receives the TAPE display data, it puts H (4V) out
of #28 (ILMI TAPE). Keeping the level of #28 High, it shifts
#27 (ILMI TUNER) to L (OV). When it receives the TUNER
display data, it puts L (OV) out of #28 keeping #27 High
(4V).
When
#27 is H (4V), Q1 turns on and the TUNER LED ar-
ray turns'on. When # 28 is H, Q2 turns on and the TAPE LED
array turns on. Both LED arrays turn on for a short time when
the TUNER or TAPE is depressed because #27 and #28 are
initially H. When the Door opens,
#27 and #28 shift to
L (OV) and turn the LED arrays off.
PD7005
4
al ios be
(250kHz)
d. FL Display Drive Circuit.
Fig. 7 shows the FL display drive circuit. Fs filament is heat-
ed by AC. The potential at the anode and grid should be-more.. =:
.
than 10V DC higher than that at filament to turn the FL on.
A DC-DC converter has been employed to obtain two vol-
tages. One is to shift BT +B (+13.2V) to —30V. This be-
comes the V-negative source for displaying. Another is to ©
obtain AC for the eight filaments. The AC is taken out of
the transformer which has been coupled with the oscillator
built in the converter. The V~ (— 30V) is reduced to about
—14V by the zener diode (D21). The —14V is fed to the
center terminal of the transformer. Then, the DC applied to
the filament becomes a pulsive DC of —14V average. When
PD7005 puts out H (4V) for the anode and grid, the poten-
tial difference between the anode and cathode becomes
about +18V (4V — (~—14V)) and the FL turns on. Fig. 27
e. FL Display Timing
The 80-bit display data from PD4050B are decoded and put
out by PD7005
in the form of an 8-digit (grid)
x
10-
segment (anode).
In other words,
this FL display lights
dynamically.
oF
FL DISPLAY
$ R9~RI3,R18~ R22
{Pull down
resistors)
DC DC CONVERTER
Fig. 27 FL display drive circuit
22
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