Polaroid Land SX-70 User Manual Download Page 24

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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.

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.

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.

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.

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.

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

Closes

Y DELAY

FLASH DELAY

Sol. #1

Power

Down/

SA BC

Closes

Opens

Sol. #2

Power

Down

At Hight Light

Levels Early

Cameras will

take Ambient

Exposure

(does not apply to

"P" configuration (T1)

and

"P" configuration (F)

with a green power chip)

Stop

Ambient

Exposure

Blades

S4 CA

Opens

Film

Ejected

Cycle

Complete/

Closes

Opens

Sol. #2

Power Up

Sol. #15

Power Up /

Blades Open to Correct

Aperture S4 AC Close

to Power FFA

Sol. #1

Power Up

Activated

Flash delay

Sol. #2

Power Off

End

Flash

Delay

Down

S4 BC

Closes

Flash

Time

Out

FTO

Flash

Fires

FLASH TIMING SEQUENCE CHART

Summary of Contents for Land SX-70

Page 1: ......

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Page 3: ...ck therefore the batteries are always fresh as the film The four element lens has a maximum aperture of f 8 and a focusing rang from 10 4 inches to infinity The shutter is automatically controlled by a photocell and electronic timing Electrical to mechanical energy conversion is accomplished by two solenoids and a motor There are no separate diaphragm adjustement The shutter opening and closing ti...

Page 4: ... sheet of film development takes place outside the camera and can be observed by the operator As soon as the print is ejected the mechanism completes its cycle to prepare for the next exposure Following thenth exposure the flash circuit is inhibited until a fresh film is inserted Normal operation will resume when the camera is reloaded The following paragraphs describe the electro mechanicalevents...

Page 5: ... be inserted or an exhausted pack can be removed A fresh film pack is loaded into the film chamber observing color coding Figure 1 5 Under certain circunstances a partially used pack could be inserted but this action will cause some deviation in the normal counting sequence The battery is a part of each film pack and the two exposed terminals on the pack engage two contacts within the film chamber...

Page 6: ...plished through a reflect system Figure 1 8 A In the viewing mode the image passes through the lens to a fixed mirror which reflects it down to the Fresnel viewing screen The viewing path from the viewfinder eyepiece lens is from a parabolic mirror and wafer lens off the fixed mirror to the Fresnel screen On most cameras the Fresnel screen contains a circular split image aera which is used to focu...

Page 7: ...inged Fresnel viewing screen is swung upward and comes to rest in front of the fixed viewing mirror Figure 1 8 B The shutter opens and closes to perform the exposure function A first surfaced taking mirror is fastened to the underside of the Fresnel carrier assembly Figure 1 8 Viewing and shooting ...

Page 8: ...ever there is no negative to pell off and discard The SX 70 accepts a special 10 lamp flash bar that plugs into a receptacle directly over the camera lens There are five lamps in a rowon either side of the bar which must be removed rotated and reinserted after the fifth lamp has been fired Figure 1 9 Insering a flash into the flash socket closes switch S2 in the socket This action sets up the shut...

Page 9: ...d position to a suitable aperture The two blades then reverse direction and again shut off the optical path These same two blades also contain a similar although differently shaped pair of cutouts that open and close the light path to the photocell in like manner In the following description the functions of photocell cutouts is deferred until the action of the shutter cutouts is explained althoug...

Page 10: ...apidly moves the shutter blades to the closed position When the solenoid has reached the end of its stroke shutter closed it no longer requires maximum current to hold it at that postion Switch S4 located on solenoid 1 closes CB and activates an electronic circuit called the POWER DOWN CIRCUIT This reduces power Figure 1 11 B Operation Figure 1 11 A Location Arrangement of internal parts ...

Page 11: ...otocell is transformed electronically to regulate the lenght of time the fiml is exposed The shape of the opening in the shutter blades and the motion of the blades is such that all of the factors involved are continously variable throughout the exposure period this fact however is a design consideration and should not confuse the theory of the shutter operation from a maintenance point of view Wh...

Page 12: ...e shutter opening is related to camera to subject distance thus compensating for the flashbulb to subject distance to give proper flash exposure As a solenoid 1 de energizes switch S4 moves from the CB position to the CA position This switch conects VCC to the FFA Figure 1 13 A Interceptor link Solenoid 2 S2 operation Solenoid de energized When the flash delay period reaches completion the circuit...

Page 13: ...Figure 1 14 S5 being opened by the recock ram Gear train Figure 1 13 B Interceptor link Solenoid 2 S2 operation Solenoid energized ...

Page 14: ...sh timing interval the circuit energizes solenoid 1 the shutter closes and the sequence proceeds as in the ambient light mode If the bulbs in the flash bar are all used when the operator attemps to make a flash exposure all of the previously described circuitly will function up to the actual firing of the flash lamp Since there is no lamp to ignite no flash firing current will be drawn There will ...

Page 15: ...e From these two points it is distributed to its destinations by the copper foil strips of a flex circuit on the outer surface of the bottom plate The lens employed is a four element glass lens of f 8 aperture with a focal lenght of 115mm It has a focusing range of infinity down to 10 4 inches Focusing is accomplished by movement of the front element only Helical threads in the lens mount provide ...

Page 16: ...and parabolic miror Figure 2 2 Viewfinder optics exposing The special Fresnel pronouced Freh nell screen is employed to enhance the viewing image by increasing the brightness and defintion If a matte white surface were substituted for the Fresnel screen an image would still be visible However the light rays striking nearest the corners of the screen meet the screen at a more oblique angle than the...

Page 17: ... with a matte surface The ribbed surface of the lenticular screen narrows the angle of reflectance but increases the brilliance of the image within teh viewing aera In summary the Fresnel satisfies three conditons 1 it enhances focusing by distributing light rays evenly across the entire viewing aera 2 it guarantees proper focusing by nature of its acting as a ground glass thus insuring that the s...

Page 18: ...baffle is held down out of the optical path The SX 70 is unique both in its principles of operation and its functional design It can be considered as aan electronically controlled mechanical device An electronic control module substrate or ECM contains all of the electronic components with the exception of the motor control MCC integrated circuit and the flash fire assembly FFA Because the ECM is ...

Page 19: ...tographer and it causes the camera to run through a complet exposure film delevery cycle b Switch S2 places the circuitry into the flash mode Switch S2 si closed when the flash bar is inserted into the FFA on the top of the shutter housing It commands the integrated circuit in the FFA to select the first unused flashbulb and to fire the bulb It also enables the ECM to energize solenoid 2 which lim...

Page 20: ...a cycle d Switch S4 is tripped by an actuator on the plungerofsolenoid 1 theshutterbladeactuating solenoid Figure 2 8 NOTE WhenevertheSX 70shutterisdiscussed it must be noted that since the camera is a single lens reflex and focusing is accomplished through the taking lens the shutter s normal state si open not closed as in other Polaroid cameras When the shutter release button is pressed and the ...

Page 21: ...e operator has released the exposure button S1 After the exposure and when the Fresnel carrier returns to the viewing position S5 is closed by the recock ram and stops the camera cycle f Switch S6 is closed by openong the camera to the picture taking position Its disconnects the negative side of the battery from the commun return ground when the camera is folded to assure the removal of power from...

Page 22: ...b The operator opens the front cover Switch S7 opens and removes battery power from the camera 3 Function Sequence Switch Action Result 1 closes Initiates exposure cycle and causes circuitry to take and deliver the pictures 2 closes Connects circuitry to take flash pictures 3 opens Initiates Y 40 milliseconds delay Power down solenoid 2 in the flash mode 4 CA closes Controls power to solenoid 1 dr...

Page 23: ...here is insufficient light to correctly operate the integration circuits the system will automaticall terminate the exposure within 14 to 30 seconds taken until mirror bounce has subsided d The operators closes and latches the front cover S7 closes power is apllied and the camera eject the dark slide NOTE During this action and in certain other operations other switches actuate and functions occur...

Page 24: ...he 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 m ...

Page 25: ...o bring the split Fresnel image into focus a cam molded into the rear surface of the focus wheel moves the component identified as the cam follower assembly The trim link coupled to the trim assembly is pinned to the cam follower in such a way that follower movement is also directly influenced by the setting of the trim wheel The trim wheel is the lighten darken control on the photocell F SHUTTER ...

Page 26: ... 2 is energized Fastened to the plunger is pull down bar when the plunger pulls this bar down it moves the interceptor into the position where it will intercept a pin the stop pin on the walking beam Figure 2 9 A Now when the shutter blades move towards the open position theywillbeinterruptedbythemechanism just described which means the maximum size of the blade opening aperture is determined by t...

Page 27: ...elay 40 milliseconds delay which allows the Fresnel carrier to come to rest after its travel This eliminates bouncing caused by the sudden stop of the carrier on the mirror cover At the end of the Y delay power is removed from solenoid 1 allowing the spring to open the shutter for exposure and moving S4 from CB to CA position When the proper exposure level is reached the photocell trips the Schmit...

Page 28: ...y is collected before the end of the flash delay the blades will be closed as in ambient picture However on newer cameras P configuration shutters the flash will fire whether or not sufficient ambient light si available At the end of the flash delay the blades at this point are open to the aperture dictated by focusing power is removed from solenoid 2 and the discharge flyback voltage triggers the...

Page 29: ... counter Shutter close Shutter starts to open Starts integration ambient Motor starts Fresnel starts down Integration 20 to 35 ms Shutter at full open f 8 16 Mirror continue to rise Mirror at rest Y delay activated Solenoid 1 power up Solenoid 1 power up Shutter starts to close Motor braked Cam stopped at 20 Electronic latch ON S1 may be opened Cam rotates Mirror released OPENS 26 34 AMBIENT EXPOS...

Page 30: ...f visible mechanical damage For this reason a well defined series of checks observations and tests must be followed This section of the manual defines these procedures Theprimarypurposeofanyfaultanalysisprogram is to reduce the investigation time to a minimum Thus it is not only important to establish a fixed routine but it is mandatory to acquire the maximum amount of information from each step o...

Page 31: ...and flash simulator 6 Take flash pix at 10 4 check premature dark slide 7 Check for dirty rollers and film catcher spring C FINAL VISUAL 1 Check optical path 2 Fresnel cosmetics per standards chart Split image 3 Wafer and 3 eye lens 4 Entrance and exit pupil position D SHUTTER COSMETICS 1 Chrome 2 Lens conditions 3 S1 button and photocell conditon trim wheel decal 4 S1 remote and flash socket cond...

Page 32: ...1 In use the system subsitutes for the film pack giving a steady reliable source of power a Plug the pack simulator into the power supply being careful to observe polarity ground is negative b Set the power supply switch to VOLTS and turn the supply ON c Adjust the output to the desired volatge 5 8v normal NOTE Except on Lafayette made units the power supply mete is not adequate to set the voltage...

Page 33: ...gned with the bottom part of the line or it may be displaced to the right If displaced to the right acceptable it should still be touching the lower part of the line 5 If the upper part of the line is displaced to the right so far that it does not touch the lower part of the line or if it is displaced to the left out of tolerance the tolerance levels are exceeded and the camera must be rejected Co...

Page 34: ...heel still set it its infinity position look through the camera while turing the lens This is done by maintaining pressure on the tool While turning it you will be able to see the target through the opening in the tool c When the image is sharpest release the special tool to reengage the refocused lens to the focus wheel Continue setp 6 Non Spring Loaded Idler Gears a Remove the camerar from the c...

Page 35: ...g of the SX 70 camera The earlier model Comprehensive Tester Model A consists of three interrelated units the lightbox the electronics module and the power supply Figure 3 6 Comprehensive Tester Model B Figure 3 7 also consists of three interrelated units the Comparalumen calibrated ligh source the electronics module and the mounting horn or holding fixture The purpose of both tester models is to ...

Page 36: ...Release the exposure button actuator All of the meters will reset automatically 8 Repeat steps 5 through 7 twice a total of three times The exposure readings observeted must be within specifications 9 Move the light level selector to 6 25 Repeat steps 5 through 7 The reading must agree with specifications 10 Move the light level selector to 800 Repeat steps 5 through 7 All readings must agree with...

Page 37: ...the socket on the camera and close the S2 CLOSE OPEN SWITCH 9 Set the light level selector to 800 cdls ft 10 Set the flash mode aperture switch to 8 11 Block any light from the photocell on the camera using a square of cardboard or other material 12 Depress the exposure button and observe the APERTURE meter 13 Record the 8 APERTURE reading and compare it to the STANDARDS Chart 14 Remove the tape f...

Page 38: ...top pushbutton on the electronics module and read the meter adding 1 stops to whatever the meter is indicating 4 Light Leak Tester Figure 3 8 Caution When using the light leak tester always hold the fixture so the camera is in the uppermost position witgh the lens pointing down There is no latching device on the fixture and the camera could slide off it the fixture were pointed down The light leak...

Page 39: ...ixture trigger 3 Examine the camera for light leaks Gently flex the boot while looking for leaks Note the location of any light leaks You may see a small amount of light in the aera where the boot joins the shutter housing This is light emanating from the substrate and is normal Allow the camera cycle completion and remove the fixture 4 Turn off the power 5 Repair any light leaks noted in the prev...

Page 40: ...ces of test equipment is that the simulator relies on an external power supply while the function tester ahs a built in power supply The steps listed in paragraph b Test apply to both units Remember if the shutter tests satisfactorily at 5 volts the test must be repeated at 6 4 volts Set up 1 Using a VOM check for shorts on the shutter before setting it on the tester Not necessary for plastic base...

Page 41: ...Blades close motor runs Blades close motor runs Blades close motor runs no flash Blades close motor runs Blades close motor runs Blades open motor brakes Flash Mode flash array inserted into shutter Close S1 Open S5 Open S1 Open S3 Close S3 Close S5 Open F1 thru F5 consecutively repeating above test between each switch opening Blades close motor runs Blades close motor brakes Blades close motor br...

Page 42: ...lash pictures are critically dependent on accurate focusing a poor viewfinder system will make the taking of good flash pictures difficult Failure Analysis Chart 5 will enable you to trace most problems in the viewing system to their source Corrective actions are shown and where they are complicated are presented in Section IV Presented here are several checks with require greater detail than the ...

Page 43: ...age e To be within acceptable limits the pupil a bright circular image must appear in the center of the square opening in the face of the gage If the pupil is not in the center adjust the optics system according to instructions in Section IV Viewfinder Sytem 2 Entrance Pupil Test a Set the focus wheel to 10 4 b Hold the camera at arm s lenght with the taking lens toward you and a bright light sour...

Page 44: ...th the marks shown in Section II of the chart If the mark exceeds that shown on the chart the Fresnel is not acceptable c ViewtheFrenelscreenagainstthebackground of Section III on the chart The conditions shown on the chart are the maximum acceptable limits for Fresnel defects If the Fresnel being examined has defects which go beyond those shown on the chart reject the Fresnel Note that an illustr...

Page 45: ...ee parts one CAMERAANALYSIS forproblemanalysis when the camera is completely assembled two OPTICAL ANALYSIS for analysis of the viewfinder parts three SHUTTER ANALYSIS for detailed shutter analysis The SHUTTER ANALYSIS charts should be used only after the shutter has been unsoldered from the camera If repairs and or replacements are indicated the procedures are described in Section IV ...

Page 46: ... watt resistor across the VCC and NPN terminals as shown This procedure does not apply to mid cycle shutdown Refer to the Failure Analysis Charts NOTE One 10 pad flex circuits these are the TP6 and TP30 terminals One 8 pad circuits these are TP4 and TP21 terminals One 7 pad flex circuits where the PNP pad is eliminated the NPN terminal is located directly adjacent to the VCC terminal Refer to the ...

Page 47: ... familiarity with the system is gained repair people can rely on the failure analysis charts to troubleshoot camera problems When the charts lead you to a repair procedure refer to Section IV Repairs and Adjustments for the necessary information Set up the test equipment as shown in Figure 3 18 The film pack simulator is inserted into the camera and the negative lead from the VOM is connected to c...

Page 48: ......

Page 49: ...ont cover release latch on the right side of the camera bed 3 Applypressuretothesideofthecoveradjacent to the cover hing aera Press toward the gear train side of the camera This will release the front cover On newer models detach the front cover from the right side gear train side only 4 inspect and clean the rollers and gears with a Q tip moistened in water If film developer is observed under the...

Page 50: ...hereby causing excess play between the latch and retainer To resolve this problem perform the following procedures a Confirm that problem is not caused by loose screws on the spread system assembly by closing the front cover and while rocking it slightly observing for excessive play b Two vendors produce the spread system assembly bracket Figure 4 2 One vendor Ramcel makes the bracket with a retai...

Page 51: ...Figure 4 4 Comparison of decal before and after front cover closure Figure 4 3 Bending the stop latch ...

Page 52: ...captures the spread system frame When making any repairs requiirng replacement of either the spread system or the front cover assembly replace the old spread system with a new one If you install a new spread system in an old front cover you must remove the light seal before installing the new spread system The new light seal is adhered directly to the spreader before the spreader is installed in t...

Page 53: ...ts surface damaged beyond cleaning Should any of these faults be evidenced replace the assembly NOTE On older cameras a coding system is used to match Fresnels and mirror covers When changing mirror cover and Fresnel assemblies correct color coding must be employed to prevent unacceptable tolerance buildup This is usually demonstrated by difficult cloding the camera etc The chart below shows the c...

Page 54: ...the camera then slide the cover from the assembly 7 remove the inner frame to boot retainer screws Figure 4 8 8 Remove the four shutter housing retaining screws from the rear of the shutter mounting hinge bracket Figure 4 9 Check for square head or Bristol head screw Replace with same type Caution While the shutter is detached from the mounting bracket make sure no mechanical stress is put on the ...

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Polaroid Land SX-70, User Manual

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