The volume is automatically muted for 3 seconds

after the key pressure and is immediately restored

at the release of the key.

Tuning speeds are as follows :

- FINE TUNING UP/DOWN

See description of pin 4.

- DIGITAL AFT ON

See description of pin 17.

- VOLUME UP/DOWN

See description of pin 15.

- MAINS ON/OFF

See description of pins 25 and 26.

Band

Number of Tuning Steps Second

Time 0

After 1 s

After 2 s

After 3 s

VHF I

VHF III

UHF

CATV

64

64

16

16

128

128

32

32

256

256

64

64

512

512

128

128

STORE COMMANDS

2 modes of operations are available.

a)store

b)memory addressing

In order to protect the memory, the store function

is internally disabled after one store cycle.

It is enabled after a program change or a tuning

operation (it is not disabled by the Digital AFT

control).

a) STORE. The tuning information (Tuning D/A,

Fine tuning D/A and band) is stored in a previously

selected memory address when this command is

issued.

b) MEMORY ADDRESSING. The tuning informa-

tion can also be stored with this command followed

by the memory position selection.

When this command is accepted all the memory

LEDs are blanked.

Selection of the memory position initiates the store

operations and restores the display.

MUTE ON/OFF

See description of pin 15.

PIN 25 : MAINS ON OPTION INPUT

memory 1 is read.

condition.

PIN 26 : MAINS ON/OFF OUTPUT

Switch on of the set is controlled by the Mains on

command issued for more than 0.3 s. The output

transistor is set in the off condition to drive through

an integrated pull-up resistor, an external NPN

transistor.

+5V

Figure 15

At each Mains on command a memory read out

a 1 second delay starts when the mains output is

switched off. For a correct reading of the memory

V within 1 second after a Mains on command.

In case of automatic switch on at power on caused

by pin 25 at GND, the total delay is of 1.13 second

mains on).

The Mains on/off command, if repeated, will switch

the output on (set off).

is present.

Next Mains on command will switch the set at the

previously selected memory address and a read

operation will be performed.

PINS 27-28-29-30-33-34-35-36 :

MEMORY ADDRESS OUTPUT

These pins operate as output only for display of the

selected memory location. Max drive capability is

of 15 mA/1.2 V with the exception of pin 36 that is

of 30 mA/1.5 V.

Direct memory selection is only possible by remote

control. A local memory up/down command is avail-

able in case of emergency.

Pin 32 must be grounded.

If pin 31 is grounded, the memory position 9 to 16

are skipped in case of memory up/down com-

mands.

For normal operation pin 31 can be left open or,

PINS 31-32

See description of pins 27 to 30 and 33 to 36.

PINS 37-38-39-40 : BAND INPUT/OUTPUT

These outputs are provided to select up to 4 bands

via external PNPs.

If one or more bands have to be skipped, the

corresponding outputs have to be short-circuited to

M491B

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