Polaroid SX70 manual Flash Timing Sequence Chart

k- If the operator has removed pressure from exposure button all power will be removed and the shutter blades will open to permit viewing. If the button has not been released, the shutter blades will remain closed until the operator removes his finger from the button.

l- When a flash bar is placed in its socket, it closes switch S2. This switch connects the ECM in the flash mode. All of the mechanical sequences will remain as just described. The ECM however, will now provide power to solenoid #2 when switch S5 (in the gear train) opens, and will maintain it in a power down condition when S3 opens.

m- Within the shutter assembly a cam follower is driven by a cam on the focus wheel and arranged so that it will mechanically stop the travel of the shutter blades relative to the focus distance. When solenoid #2 is not energized, a spring on the cam follower prevents engagement of the cam follower and the shutter mechanism functions in the ambient exposure mode. When the ECM is programmed for flash, solenoid #2 is energized and the shutter openeing is controlled by focusing distance.

n- When making a flash exposure and the shutter blades start to open, the interceptor will be set to a position determined by the focusing mechanism but out of the path of the interceptor pin. When solenoid #2 is energized, it pulls the interceptor into the pins path of the blades and stops them

at the aperture for flash exposure at the set distance (Figure 1-13). The interceptor latches in this position. At this time, the ECM removes the power from solenoid #2. The solenoid, like any inductive device, produces a flyback voltage when its magnetic field collapses. This flyback voltage is used to trigger the ECM which, in turn, applies power to the FFA to ignite the next unused flashbulb.

o- The shutter performs an additional function in the flash mode. One of its circuits examines the #1 flashbulb contacts and by virtue of the resistance determines whethever or not the bulb has been fired. If the #1 lamp is exhausted, the circuit scans the #2, etc. When an unused lamp is located, the firing circuit remains connected to the lamp until is used.

NOTE : It is important to be aware that in early cameras the timing (integration) circuits of the substrate continue to function even though the insertion of a flash array has placed the substrate in the flash mode. Thus, if the ambient light level is high, the picture may be made by ambient light without firing the flash. Also, if all the flash lamps are expended and a picture is taken, an ambient light exposure will result. The photographer will recognize this situtation by the absence of a flash. However, he may still get an acceptable picture. the aperture in this case will be determined by the flash to subject distance.

FLASH TIMING SEQUENCE CHART

				End
	Sol. #1	S3		Flash
				Delay
	Power	Opens
	Down/	Sol. #2	Activated	Sol. #2	Down
Sol. #1	SA BC	Power	Flash delay	Power Off	S4 BC	S3
Power Up	Closes	Down	FD	FF	Closes	Close

S1

Closes

S4 CA Opens

S5

Opens

Sol. #2

Power Up

Y DELAY

Blades Open to Correct Aperture S4 AC Close to Power FFA

FLASH DELAY

Sol. #15
Power Up /	Film
FT
	Ejected

FTO Flash

Flash Time

Fires Out

Cycle

Complete/

S5

Closes

At Hight Light	Stop	Blades
Levels Early	Ambient	Close
Cameras will	Exposure
take Ambient
Exposure
(does not apply to
"P" configuration (T1)
and