Circuit Description - Kenwood HM-901 Service Manual

1. DESTINATION LIST OF TUNER
1-1 Destination List of Tuner
Receive
Desti- Channel
BAND frequency
nation space
range
87.5MHz~
FM 100kHz +10.7MHz
108.0MHz
K1
530kHz~
AM 10kHz
1700kHz
87.5MHz~
FM 50kHz +10.7MHz
108.0MHz
E1
531kHz~
AM 9kHz
1602kHz
87.5MHz~
FM 50kHz +10.7MHz
108.0MHz
E3
(RDS)
531kHz~
AM 9kHz
1602kHz
K2 or E1 is changed the setting "DSW1".
M
(DSW1=1 : K2, 0 = E1)
0 : NO DIODE 1 : DIODE
2. TEST MODE
2-1. Initializing
The system is initialized when the power is turned on while
pressing the POWER key.
(1) Contents of operation
EAll the functions are initialized.
2-2. AMP test mode using main unit's keys
2-2-1. Entering the AMP test mode
ETurn on the power while pressing the BAND key.
2-2-2. Canceling the AMP test mode
E By turning off the power, the system is initialized and the
test mode is canceled.
2-2-3. Contents of AMP test mode
(1) Automatic POWER ON
E The POWER ON state is entered whenever the power is
turned on while pressing the BAND key. All functions are
then initialized and activated in the all-lighting mode.
ESub-clock oscillation diagnosis function
The oscillation diagnosis (existence of oscillation and
measurement of period) of a sub-clock is performed
before the test mode is entered. If the diagnosis result is
OK, the system enters the test mode.
If the diagnosis result is NG, the oscillation of the sub-
clock is diagnosed again. If the result is OK, the system
enters the test mode. If the diagnosis result is continu-
ously NG five times, the system stops with ERR 1 and
ERR 2 displayed.
(2) All-lighting mode
E All the fluorescent display indicators and LED lamps light
when the power is turned on while pressing the BAND
key.

CIRCUIT DESCRIPTION

DIODE SW(X14)
PLL
1F reference DSW1 DSW2
frequency
D26 D29
25kHz
1 1
+450kHz 10kHz
25kHz
0 1
+450kHz 9kHz
25kHz
1 0
+450kHz 9kHz
X 1
X : SWITCHING TRANSISTOR
E After that, the all-lighting mode is canceled when any
main unit's key is pressed. The normal display obtained
when the selector is set to TUNER then appears.
3) CONSTRAINT IDLING CURRENT CHANGEOVER MODE
when selector is set to positions other than TUNER.
[PURE A key] Every time this key is pressed.
idling current mode is selected cyclically.
î
NORMAL(B class)îPURE A(IDLING MID)îPURE A(IDLING HIGH)ì
PURE A NORMAL (MIDíîHIGH AUTO CHANGEOVER)
IDLING CURRENT MODE
PURE A IDLING MID (constraint)
PURE A IDLING HIGH (constraint)
PURE A NORMAL MID (less than VOL.10.00)
PURE A NORMAL HIGH (more than VOL.10.01)
(4) Others
E The AMP test mode is not terminated even if the selector
is set to positions other than TUNER.
E In the AMP test mode, the muting during mode selection
is not controlled. However, the operation during the
power-on sequence is the same as the normal operation.
E The SP protection operation is also the same as the nor-
mal operation.
E In the AMP test mode using main unit's keys, the keys
below provide a special operation according to the posi-
tion where the selector is set. The main unit's keys
except described below and the rotary encoder provide
the normal operation.
(5) When selector is set to TUNER
Key
PURE A key Increments the P.CALL every time this
key is pressed.
N.B. key Decrement the P.CALL every time this
key is pressed.
ENTER key Selects the display cyclically in the order
below every time this key is pressed.
@ Write data in the unused area of E2PROM, then read the
written data. If the read data is the same as the written
data, "RAM OK" is displayed in the fluorescent display
indicator. If the former is different from the latter, "RAM
NG" is displayed.
A Set the TUNER ATT to OFF and display the S level in
hexadecimal when the ENTER key is pressed. ("ATT
OFF **" is displayed in the fluorescent display indicator.)
B Set the TUNER ATT to ON and display the S level in
hexadecimal when the ENTER key is pressed. ("ATT ON
**" is displayed in the fluorescent display indicator.)
* The special display using the ENTER key is continued until
the next operation is carried out. (**: S LEVEL)
When keys other than ENTER are pressed in items @ to B
above, the TUNER ATT is set to OFF and the normal display
appears. The operation corresponding to the key that has
been pressed is performed in this case.
R-SE9
DISPLAY
PURE A M
PURE A H
PURE A M
PURE A H
Operation
3