Pioneer KE-5100 Service Manual page 7

* Switch Matrix
As shown in Fig. 9, the touch-type switches and tuning
switches are each grouped together on the front panel. The
operations of the diodes and transistor are now described.
The five diodes, D24~D27 and D34, are designed to safe-
guard against malfunctions caused when the touch-type
switches are depressed twice.
D19 and D28 serve the same purpose.
The four transistors—Q25, Q27, Q28 and Q30—function as
transistor switches when the control voltage is applied to each
transistor base via the resistances. In particular, the diode
switch connected at D19 is installed so that the channel
spaces in the USA AM band can continue to be set at 10 kHz
e Scan Operation
When the SCAN key is depressed with the radio on at the FM
1 position (with 030 and Q27 ON and Q28 OFF), PD7003 is set
to the SCAN mode and the frequency division ratio N of the
programmable divider increases one step at a time during a
fixed time period.
Due to the phase-locked loop configuration the tuning voltage
also rises and the reception frequency moves up the frequency
scale. The absence or presence of broadcasting stations is
identified by PD7003 which judges whether or not 025 has
turned ON with every 1-step change, and N is stopped from
changing. In other words, the scanning operation can be
FM
Front End IF Amp
IC1,1C2
M5215L
FM+Bo
AM RF Amp
MU PULL ie oe 034 a
oe O\Si=! mse re [@
O21 K2
ONe HU e ects a
Seca
IFAmp/FM Detector Suppressor
AM Tuner IC
KE-5100/6100
and when these spaces are changed to 9 kHz, all that need be
done is isolate the D19 diode. a
The ""A/B" of the switches signifies that ''A'"' is ON and 'B"' is
OFF, and at places where there are transistor switches + B is
applied to the base during the ON mode. Pins 23 ~ 28 serve as
. the digit pins which are "L" active types while pins 19~ 22
have built-in pull-up resistors. If the switches are OFF, pins
19 ~ 22 are in the "'H" state. When one of the switches is set to
ON, one of the 19 ~ 22 pins goes to "L'"' with the digit timing,
PD7003 judges which switch has been depressed and it moves
into the operation.
1c
"4 PD7003
Fig. 9
stopped by turning Q25 ON when a station has been picked
up.
In Fig. 10, pin 11 of 1C3 PA4007 serves as an open collector
output which is open for the width of the station (fg) + 40 kHz,
and Q25 has been turned ON through R143, D40 and R146.
Similarly at the AM position (O30 and Q28 are ON and Q27 is
OFF) 1C6 ~PC1215V is an open collector output with pin 19
open for the narrow-band width (fg 5 kHz) of CF4 and C F5in
the schematic diagram, and Q25 is turned on through R144,
D39 and D146.
Noise MPX
Decoder
PD'7003
Fig. 10-