Sony Mavica MVC-FD85, Руководство по обучению

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Overall Block
The circuit makeup of the Mavica Still Picture Camera consists of the
power supply and several sections necessary to display a picture on the
LCD panel and store the picture onto a 3.5” floppy disc. The main FC-72
board is fed by power input from the FU board. Meanwhile, the FC-72
board supports several stages and assemblies.
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Camera stage
•
Flash unit assembly
•
Floppy disc assembly
•
LCD stage
•
LCD Backlight stage
The main FC-72 board is not repairable because it contains a BGA IC. If
this board is bad, the entire board is replaced.
Power Supply
All camera features function whether powered by an AC adapter or the
Info-Lithium Ion battery. When the battery is used, two transistor switches
are used to connect the battery to the main power path.
Battery Power
When an Info-Lithium Battery is inserted, HI Control (Human Interface
Control) IC404 receives Ever 3.2V power and determines that the power
source is the battery. The “Batt Unreg” line passes about 7.2Vdc battery
power from the FU board to the FC-72 board. This line is applied to IC404
for battery sensing and D401 to make Ever 3.2V that powers IC404. D401
feeds regulator IC401 that outputs the Ever 3.2V. This Ever 3.2V is used
to power IC404 and charge the timer backup battery BT701 (via D410).
With IC404 powered, it looks at its Batt Unreg input from F004 to identify
the power source.
Powering the camera from the battery employs the Fast Charge On cir-
cuit of Q001 and Q004. Sliding the power switch (key input buttons)
instructs IC404 to output a HIGH from the Fast Charge On line. This
HIGH turns ON Q001 and Q004 on the FU board. Q001 and Q004 con-
nect the battery voltage to the fuses F001-3 and F005, which apply power
to the DC-DC Converter IC001. The converter produces voltages for the
camera.
AC Adapter Power
The AC adapter (not shown) produces about 8.4Vdc (1.5A capacity) to
the DC In terminals of the FU board. This DC input is fused before enter-
ing the power supply on the main FC-72 board to power IC404 and the
camera’s DC-DC Converter. Within the main board, D402 directs this
input voltage from F003 to Regulator IC401. IC401 makes the Ever 3.2V
to power HI Control (Human Interface Control) IC404 and to keep the
BT701 battery charged (via D410). Now that IC404 is powered, it detects
that the power is supplied from F003 that comes from the AC adapter.
Battery Charging
Conditions - Battery charging can only take place when both power sources
are present and the camera is OFF. Before battery charging is initiated, a
test charge using Q001 and Q004 is performed to determine if charging is
necessary. This test charge occurs when the battery is inserted or when
the camera is turned off (so the battery charge conditions are just met).
Battery Charging Conditions
Name Purpose Location
Batt Unreg Battery presence From F004
BL Unreg AC Adapter presence From F003
Power OFF Power OFF Internal IC404 on/off latch
A good way to determine the condition of the battery is to measure the
voltage and discharge current with a controlled load. A more efficient way
is to measure the voltage and current during a test charge. A test charge
is an ideal way to check the condition of the battery.
Operation - IC404 outputs pulses from “Init Charge On” to turn ON tran-
sistors Q002 and Q003. The DC In voltage passes through D002 and the
two transistors to test charge the battery. The battery’s microprocessor
determines if charging is needed and sends data on the “S” line to inform
IC404. If charging is needed, IC404 outputs a HIGH on the FAST CHARGE
ON line to connect the battery to the DC In voltage.