HP406 Service Manual
Page 8 of 12
2.7 Battery
The battery connects to the contact pins(
CN201
and
CN202
) on the bottom end of the Radio. The positive
terminal of the battery connects to the ON/OFF Volume Control switch (
S201
)
and the negative terminal connects
to chassis ground. Low battery sense
R101
/
R102
, voltage regulator
Q222
and transmit power module
Q407
.
The battery voltage status is monitored by the microprocessor
Q17
Pin
61
which senses the battery voltage
through the
BATT+SW
line by means of
R51
/
R49
. When the battery voltage is approximately 5.8V, the
microprocessor considers the battery discharged and switches off the circuits of the radio.
When the Radio is on a channel with no tone programmed, the BATTERY SAVER Mode is enabled when
programmed.
In the BATTERY SAVER mode, the microprocessor
Q17
generates a square wave signal at Pin
48
which is
applied to the inverter
Q10-F
. The signal’s duty cycle varies according to what the POWER SAVE TIMER is set.
When the microprocessor
Q17
Pin
48
goes high (approx. 5 V)
Q226
(receiver module) is biased off,
Q225
is
biased on,
Q224A
is cut off, and
Q223A
is cut off, thus turning the supply off to
IC6
.
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