Servicing - Sony DSC-S75 Training Manual

2. Q405/Q406 switches power to the converter on and off and is controlled by the CHARGE ON/OFF line. To
initiate the charge cycle, IC102 on the FR-181 board outputs a HIGH on the STB_CHARGE line. The battery
charge lamp blinks while the capacitors charge up.
3. Once the capacitors have fully charged, the FLASH CHARGE DETECT circuit outputs a LOW, which overrides
the HIGH on the STB_CHARGE line. This shuts off the flash dc-dc converter.
4. The FLASH CHARGE DETECT also outputs a LOW on the XSTB_FULL line to IC102, informing it that the
flash is ready to fire. The camera will not take a picture if flash is needed and the XSTB_FULL line is did not
go LOW.
5. When the shutter is pressed down partially and the camera detects that flash is needed, the STB-PLUNGER
line from IC102 outputs a HIGH, triggering the flash pop-up solenoid and popping up the flash.
6. The pop up switch closes when the flash reaches the up position, pulling the XSTB_POPUP line LOW and
signaling IC102 that the flash is ready. The camera will not take a picture if flash is needed and the
XSTB_POPUP line is not LOW.
7. When the shutter is pressed fully down, XSTRB_ON from CAMERA DSP IC301goes LOW, firing the flash.
The flash duration is determined by the pulse width.
8. The photo transistor inside the lens controls the on time of the flash. The output from the photo transistor is
applied to CAMERA DSP IC301. Once sufficient light has reached the CCD, IC301 switches the XSTRB_ON
line HIGH, turning off the flash.
CAUTION – SHOCK HAZARD
X Never touch any exposed part of the flash assembly without first discharging the storage capacitor. Make a jig
from a well insulated 1K 1W resistor to discharge the capacitor.

Servicing

Discharging Storage Capacitors
CAUTION: Do not handle the BT-006 board without first discharging the flash storage capacitors. The capacitors
charge up when the camera is turned on and can maintain a charge even after the unit has been off for many
hours or days.
Make a discharge jig from a 1K ohm - 1W resistor (Sony pn: 1-215-869-11) and two hook clip leads.
41
16. DSC-F707 Flash Circuit