Amron 8225-HP, Instruction Manual

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THEORY OF OPERATION
ELECTRICAL (cont’d) 9.3
AUDIO POWER AMPLIFIERS - U6 and U7 are audio power amplifier integrated circuits
connected in a bridge configuration. The output “floats” at approximately 6 volts and should never
be connected to ground. The amplified audio “output” signal is directed to divers or tender through
relays K1 and K2.
BIAS LEVEL - Resistor R39 and diode determine the bias voltage for the amplifiers U1, U2, U3,
U4, and U5.It should be 4.3 Volts measured to /- 10%.
AUDIO OUTPUT VOLUME CONTROLS - R104, R105 and R106 attenuate output levels to diver
earphone and tender headset.
2-WIRE OPERATION - Input audio signals from divers are amplified through the circuitry
described previously, and directed to the tender’s headset and speaker through relays K1 and
K2.When tender actuates the push to talk switch, tender’s speaker and headset are connected
through relay K1 to microphone input. Divers are connected to audio output through relays K1
and K2.
SWITCHES - S1 AND S2 break connections to diver microphone jacks. Crosstalk switches S3 and
S4 connect appropriate diver microphones to audio output.
SIMULCOM (4-wire) - Tender and diver microphone are connected to amplifier inputs at all times.
Tender headset and diver earphone are connected to audio output at all times.
BATTERY CHARGER - Maintains batteries at full float charge of 13.8 To 14.4 Volts. Front panel
AC power “LED”, indicates when AC power is applied to unit. Charger protects batteries from
overcharge by automatically switching to float charge when batteries are fully charged.
BATTERY SENSE CIRCUIT - Electronically senses voltage from battery. Controls panel “LED”
(battery condition indicator) which indicates; steady light - battery is Good, blinking light - low
battery, no light - below reliable operational range or no voltage. Sense points, above 11 volts +/-
.25 volts = Good (steady light). 11.0 to 10.0 volts +/- .25 volts = Low (blinking light). Below 10.0 +/-
.25 volts = Bad, battery is below reliable operating range. Rechargeable batteries should not be
operated below their normal operating voltage, permanent damage can occur. They should not be
left in a non-charged state.
We strongly recommend the batteries be put on charge and left on charge when not in use. This
will solve two problems, one - the unit will always be ready to be put in service, and second - it
ensures the batteries will be charged as soon as the unit is returned from the field. Cold weather
operation, expect reduced battery performance under cold condition, also discharged batteries are
subject to freezing and damage. The capacity of the battery will be reduced by approximately 40%
at temperatures of 0
o
F . Charging of the batteries should be done within the temperature range of
32
o
F to 104
o
F. The ideal temperature for recharging is between 50
o
F to 86
o
F.
Battery Life - Several factors effect the life of the battery. These factors are discharge rate, depth
of discharge, charge rate, operating temperature, and storage temperatures. The general rule of
thumb is 300 charge cycles, or 3 years. The failure of the battery is not a complete catastrophic
failure at the end of its life but a general deterioration in performance over the life of the battery.
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