SX-70 Darkslide Troubleshooting

8/2/2019 SX-70 Darkslide Troubleshooting

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1. Set the light-level selector at 100.2. Depress and hold the exposure button actuator.3. Record the EXPOSURE meter reading.4. Remove the camera from the test set and setthe trim wheel to the maximum darken posi-tion (fully counterclockwise).

5. Reinstall the camera on the tester and engagethe flash simulator plug. ~i_ 6. Depress and hold the exposure button actuator. :The EXPOSURE meter must indicate no greaterdifference than current specifications relative tothe step 3 reading.

7. Raise the flash simulator plug, remove the cam-era from the tester, and set the trim wheel toits maximum LIGHTEN position (fully clock-wise).

8. Reinstall the camera and engage the flash simu-lator plug. .--..._,9. Depress and hold the exposure button actuator.The EXPOSURE meter must indicator no great-erdifference than current specifications relativeto the step 3 reading. . I

10. Raise the flash simulator plug, remove the cam-era from the tester and reset the trim wheel toNORMAL.L. FOLLOW-FOCUS TESTThe follow-focus test is used to determine howwell the shutter blade opening follows the focus-ing of the lens in the flash mode of operation.The APERTURE meter is used in this test. It iscalibrated in stops and when the test is performed,it will indicate stops deviation from the designaperture. To perform the follow-focus test, pro-ceed as follows:1. Set the camera focus to infinity. (The lens isturned all the way in when set at infinity.) Set I.'the LID control at its mid-range position.

2, Remove the front coverfrom the camera andinstall the S7 switch closure as described under"Initial Checks to be Performed".3. Install the camera on the horn of the tester. Thecamera should go through its dark-slide cycle.4. Install the flash simulator plug into the socket(lJ1 the camera and close the S2 CLOSE-OPENswitch.

5. Set the focus wheel actuator to infinity. (Matchcamera focus setting.)6. Set the camera supply voltage to 5.8 volts, usingthe tester VOLTAGE ADJUST control, ifrequ_iEed. __

--- 7. Engage the focus wheel actuator with the focuswheel on the camera and rotate the focus wheelto 10.4 inches or the 8 foot position.

8. Set the light level selector to 800 cdls/ft2 .9. Set the flash mode aperture switch to 8 ft. or10.4 inches as selected in step 7. Perform thetest at both 10.4 inches and 8 foot settings.10. Block any light from the photocell on theearnera using a square of cardboard or othermaterial.

11. Depress the exposure button and observe theAPERTURE meter.12. Readings must conform with currentspecifica tions.13. If the reading is high at the 8-foot setting, andthe needle goes off scale at the 10.4 inch set-

ting, the interceptor mechanism is defective.-- R ep arr'as cfes crib ed iii-S -ection rv .14. If on-scale readings are obtained bu t the I 0.4-inch reading is either high or low, the intercep-tor can be adjusted (Section IV). The problem

can be either the interceptor link o: the inter-ceptor cam.IS . When adjustments/repairs are complete, recheckthe follow-focus function.

M. DARK-SLIDE FUNCTIONWhen a film pack is inserted into the camera andthe front cover or S7 is closed, the blades shouldclose and stay closed through the dark slide (or afilm from a partially exhausted pack) eject. Themotor should run and the Fresnel carrier shouldraise. Fault Analysis Chart No.1 presents a logi-cal series of tests based upon the dark-slide-ejectperformance. Referring to Chart No. I,proceedas follows:1. Open the film compartment and insert a filmpack which contains a good battery. The cam-era will either complete a cycle as just describ-ed or will malfunction in one of three ways:

'. a. No action will occur when the pack is inserted.b. The camera will start the cycle but the motorwill stop before the cycle is complete.c. The camera will run continuously andkeep re-peating the eject cycle.

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2. If the camera performs the eject cycle correct-ly, skip the following checks and proceeddirectly to paragraph Q and Fault Analysis.Chart No.2. ---


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IfMalfunctionIf,upon insertion.of a film pack, no action of anykind occurs, it is first necessary to determine ifthe camera is drawing current. The SX-70 powersupply simulator (Figure 3-3) is equipped with avoltmeter and an ammeter. It includes the adapt-er which is substituted for a film pack to providepower to the camera for making tests. Check thecurrent in the following manner:NOTE: During the following tests, polarity indi-cations refer to the TEST METER leads, not forthe test pOin_!_sed.1. Adjust the power supply to 5.8 volts.2. Insert the adapter into the film compartmentof the camera. Assuming no dark-slide-ejectionfunction, there can be a zero current indicationor a high-current (in excess of 1.00 amperes)indication. The no-current condition is describ-ed first in the following paragraphs.

3. Following the procedures in Section IV, para-graph AA, remove the camera bottom cover_!ogain acces~ to the flex circuit,NOTE: For location of the following testpaints, see Figure 3-26, page 3-28.

4. With the adapter in the camera and the powersupply turned on, check for 5.8 de volts at TP-1 battery (-) and TP-2 battery (+) using theTriplett Model 801 VOM. If 5.8 volts ispresentat these two points, check at TP-3(8 - 10 pad) (-) and TP-4 (8 -10 pad)(+). Ifthe correct voltage is present at 1 and2 and not at 3 and 4, the fault lies in the solder-ed connections, the battery con tacts, or the_flex circuit itself. If the correct voltage is pres-ent at 3 and 4, proceed to step 5.

5. Check for 5.6 volts at TP-S (-) and TP-6 (+)on the shutter substrate. To gain access tothese two points, remove the shutter housing.See Section IV. If the correct voltage is pres-ent at these two points, the fault lies withinthe substrate circuits. Replace the substratea.sdescribed in Section IV. If the voltage isnot present at 5 and 6, check and repair thesolder connections or the multi wire cable.

6. If in step 2 the camera current was greater thanl.OO,amperes, proceed as follows:7. With the VOM, check for 5.6 volts betweenT P-S (-) and TP-7 (+) (Soli). If the voltageap-pears at TP-7, move the positive test lead toTP-8 (Sol 1+; S4C). The voltage at TP-8 willbe something less than 5.6 (due to the solenoid~?il resistance) bu t if voltage is present at both

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solenoid terminals and the solenoid does notpull in, a mechanical bind is indicated and thesolenoid must be removed and repaired or re-placed. If the voltage is present at TP-7 butabsent at TP-8, the solenoid coil is open andthe solenoid must be replaced.

8. If there is no fault in the solenoid, check themotor. Two conditions could cause the motorto draw excessive current; a mechanical over-load, or an electrical short circuit. Removethe power-supply simulator and remove thecamera bottom cover (Section IV). Lift theflex circuit, Section IV, paragraph V, to exposethe motor connections (Figure 3-14) TP-9motor ( -) and TP-I 0 motor (+). Use the Trip-let Model 80IVOM and check the resistanceacross the two test points (motor contacts). Itshould be approximately 2 ohms. If the motorresistance is low, replace the motor and retest.If the resistance reading is correct, check thegear train.

TP-9(COMMON)

+.TP-10

30032-3-14FIGURE 3-14 MOTOR CONNECTIONS

9. On the gear train rotate the second gear fromthe drive pinion in the counterclockwise direc-


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tion (Figure 3-15). The gear train should func- !tion with no evidence of binding while drivingthe camera through a complete dark-slide-ejectsequence. If considerable force is requIred tooperate the gear train, remove and repair/re-place the .gear train. See Section IV, paragraphM _ . .---.-~-NOTE: Do not rotate the second gear in theclockwise direction or damage to the gearswillresult.

COUNTERCLOCKWISE~~OTA_],JQN ONLy _

30032-3-15FIGURE 3-15 ROTATING 2ND REDUCTION GEAR.10. Ifall of the foregoing tests give no evidence ofmalfunction, the faulty component could bethe motor capacitor (across the motor termin-als). Replace the capacitor with one of knownquality and repeat the test..- - --~-~.--.N. CAMERA RUNS CONTINUOUSLYWhen a film pack is inserted, if the camera runscontinuously, first investigate possible faults inthe camera back.1. Remove the camera bottom cover (Section IV).Connect the YOM at TP-II (S8) (+) and TP-Ihattery (-). While observing the meter, insertthe power-supply adapter into t-lte camera filmcompartment. The meter should indicate 5.8volts during the first cycle but should drop tozero when the dark slide isejected indicatingthat switch S8 has opened. If the switch failsto open, replace the counter assembly. SeeSection IV. If the switch functions as it should,proceed to check-SS. _ _ _

2. Switch 85 is mounted on the gear-train assem-bly and its contacts are accessible when thecamera bottom cover is removed. S5 is the -

switch nearest the drive-pinion end of the geartrain. Remove the power-supply simulator andremove the camera bottom cover. Check theresistance across the 85 connectors. The resis-tance should be zero (closed switch). Whilewatching the recock ram, rotate the gear trainby hand until the ram moves away from S5.The switch should open as indicated by an in-finity reading on the YOM. If S5 does not per-form in this manner, adjust or replace S5 as;described in Paragraph Ill-S. If S5 is functioningcorrectly, check the flex circuit.

3. Connect the YOM across TP-3 (flex ground)(-) and TP-12 (flex-pad) (S5) and repeat theprocedure described in step 2. If the correctreadings (zero and infinity) are not obtained,resolder the flex circuit connections and re-check. If the correct readings are obtained,move the test leads to TP-5 (-) and TP-13(S5) on the substrate. (See Section IV for in-structions for gaining access to the substrate.)Repeat the step 2 test. If the readings (zeroand infinity are not obtained, resolder thecable connections at the substrate or replacethe cable if necessary. If the correct readingsare obtained, check the motor control signals(drive sigllal and brake signal). -

4. Check for a motor drive signal at the flex cir-cuit. Set the YOM on the 1.5 VDC scale.Connect the meter to TP-3 (-) and TP-21 (+).Read the meter while the motor is running.The meter should read 0.6 volts. When the re-cock ram releases S5, the meter reading shoulddrop to zero. If it does not, connect the meterto TP-5 (shutter pad) (-) and TP-30 (shutterNPN (+). If the meter readings are correct atthese test points, the ribbon cable is defective.Repair/replace the cable and retest. If the cor-rect readings are still not obtained, perform acheck of the shutter.---__----

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5. Check for a brake signal .not used in Fairchild)at the flex circuit. Set the YOM at the 0.5VDC scale. Connect the meter at TP-4 (+) andTP-22 (-). Read the meter while the motor isrunning. The meter needle will fluctuate slight-ly while the motor is running. When the recockram releases S5, the meter should give a distinctupward deflection (the exact value is unimpor-tant). This indicates that the brake signal ispresent. If it is not, perform the same checkat TP-6 [shutter (+)] and TP-29 [shutter (-)].If the meter performs correctly at these testpoints, the ribbon cable is defective. Repair/replace the cable and retest. If the correctreadings are still not obtained, perform a checkof the shutter.

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30032-3-17FIGURE 3-17 MANUALLY SEATING SOLENOID1 PLUNGERvery slightly in the direction of the lens (Fig-ure 3-18). Repeat step 4 and step 5 as neces-sary to correct the S4 malfunction. If theswitch cannot he made to perform correctly,replace the S4 switch and/or blade drive as-semblv. If the switch performs correctly, pro-ceed to check the motor control circuits (MCC).

6. Use the Triplett Model 801 YOM. Set themeter on the low-ohms scale. Check the re-sistance between TP-5 and TP-21 (NPN). Themeter should indicate 50 ohms and the motorshould run if the film pack is inserted. In thistest, the YOM supplies the motor run signaland measures the resistance.

7_I f the motor runs under these conditions, checkfor a rem signal. S':'t the YOM on the 15 YDCscale. Connect the' meier to TP-25 (-) andTP-27 (+). Read the meter while the motor isrunning. The reading should be approximate-ly 0.2 YDC. When the recock ram releases S5,the meter reading should increase to approxi-mately 5.8 volts. If this run signal is present,the camera should run. :f there is no run 'signal, the only remedy is to replace thesubstrate.

- - - - - - - - - - - 30032-3-18FIGURE 3-18 ADJUSTING SOLENOID 1 PIN

8. If the MCC check (step 6) produced no results,check the motor individually. Connect a jump-er wire between TP-25 and TP-27. This shouldcause the motor to run. Ifit does run, it indi-cates that the fault is elsewhere. Examine theflex circuit connections between the MCC and._. - ~ -_. -the motor (Figure 3-19). If in doubt, resolderthe connections. If this does not solve theproblem, perforrna discrete check of the MCC.

9. Use the Triplett Model 80 I YOM set at thelow-ohms scale, Check the resistance betweentest point 25 and test point 27. The resistanceshould be approximately fifty ohms. If the. resistance is not correct, replace the MCC.10. The alternate possible malfunction results inthe following partial sequence. The shutter

blades close, the Fresnel carrier lifts, and thesequence stops. When this occurs, first checkthe performance of switch S3.11. With the YOM set for low-ohms scale, connectthe meter across S3 (mounted on the gear-train

outer plate) TP-14 (S3) and TP-15 (S3). Ob-serve the meter while manually running thecamera by me~ns of the second gear in the

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gear train. At the start of the sequence, theswitch should he closed (zero ohms). Whenthe switch is contacted by the recock ram, theswitch should open (infinity on the ohmmeter).If switch S3 fails to produce these indicationsadjust and/or replace the switch (Paragraph III-S).-Ifcorrect readings are obtained, repeiCtI1-e----checks at Tp3 (flex pad) and TP~32 (S3).

__ . If the foregoing tests indicate no fault, care-fully examine the flex circuit and connectionsfor possible short circuits. If none are found,check for the S3 signalon the substrate~_3. Connect the VOM (on the low-ohms scale) atTP-5 and TP-28 (S3). Repeat step 5. If faultstill indicated, replace substrate.--.- - - ...---P. SHUTTER BLADES CHATIERC when a film pack is inserted, the shutter bladeschatter, the component most suspect is sole-r.oid no. 1. Because it is actuated by solenoid no., . the S4 switch can also be at fault. The malfunc-"':'onis the result of switch S4 changing the sole-::oid drive voltage to the power-down value be-:-cre the solenoid plunger has travelled far enough~'"'function with the reduced voltage. Perform--,,,,following checks:". Remove the shutter housing (See Section IV)

to gain access to the solenoid mechanism.:. Lse a jeweler's screwdriver and manually ac-ruate the walking beam assembly (Figure 3-20)

300323-20JEWELER'S SCREWDRIVER INWALKI NG BEAM

to determine that the assembly moves freelythrough its complete travel (shutter bladestotally closed). If there is any indication of__bin~ing, remove and repair/replace the assembly.3. If the solenoid appears to be free of any mech-anical problems, the malfunction is probablycaused by a faulty or misadjusted S4 switch.The switch itself cannot be adjusted withoutperforming a major shutter disassembly. Thedesired results can be obtained by slightlybending the pin in the solenoid plunger. As-suming the shutter-blade chatter is a result ofthe S4 switch being actuated prematurely, pro-ceed as follows: .

4. Remove the focus wheel to gain access to thesolenoid plunger.5. Use needle-nose pliers and tilt the pin veryslightly in the direction of the lens. Recheckthe camera and repeat the adjustment as nec-essary.

6. If the foregoing adjustments fail to correct themalfunction, it will be necessary to replace theblade drive assembly as described in SectionIV (paragraph AG. Install the replacementand recheck the camera. --- --

Q. EXPOSURE CYCLE CHECKWhen the camera correctly performs a completedark-slide-eject sequence, the e~p()sure sequence

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can be checked. Fault Analysis Chart No.2 graph-ically presents the checkout process. With a filmpack (or power-supply adapter installed in thefilm compartment, and the dark-slide-eject se-qucnce completed) press the exposure button(S 1). The motor should run, the shutter bladesshould close, the Fresnel carrier should lift, theshutter blades should open and close, the Fresnelcarrier should drop, the film should eject and theshutter blades should open. There are three pos-sible variations of malfunction. The camera func-tions as described, the camera does not operate,or the camera starts to run but does not completethe exposure cycle. If the camera functions cor-rectly, proceed to the exposure test, Fault Anal-ysis Chart No.3.1. If the camera fails to operate, first install aremote shutter release (Figure 3-21) in theremote connector. Operate the remote release.If this causes the C~IIi1Crao function correctly,a faulty S 1 switch is indicated.

300323-21FiGURE 3-21 REMOTE SHUTTER RELEASE2. Follow the procedures in Section IV, paragraphAE, and remove the shutter from the shuttermounting hinge bracket. With the YOMset at the low-ohr= scare, connect the meter to.TP- l I) (+) and TP-20 (-). The meter should in-dicate infinity (open circuit). Press the expos-ure button. The meter should indicate zero(closed circuit). If it does not, remove theshutter housing c " l l r 1 perform the same test withthe ohmmeter connected to the two terminalson the rear surface of the exposure button. Ifthe button is defective, replace the shutterhousing as described in Section IV. If the but-ton operates correctly, clean the two contact ..

points on the shutter. Spring the contacts for-ward a small arriount (Figure 3-22), reinstallthe housing and recheck.

30032-3-22FIGURE 3-22 SPRINGING S1 CONTACTS

3. If the camera failed to function when the re-mote release was operated, remove the shutterassembly from the hinge bracket and check thesolder connections at TP-19 and TP-20. Re-solder if necessary .

4. If the camera runs through a partial exposurecycle, first check for unwanted electrical inter-ference (noise) from the motor.5. If there is no evidence of motor noise, checkthe gear train for binding. If there is evidenceof binding, remove and repair gear train. SeeSection IV, paragraph AA.

R. PHOTOCELL FILTER AND SHUTTERTRACKING TESTSIf the camera is overexposing, the fault may becorrected by changing the photocell filter, cor-recting the shutter tracking or both. It is firstnecessary to identify the possible correction.1. Remove the photocell bezel and filter. SeeSection !V, page 4-78, AF-l 7. I2. Install the camera on the Comprehensive TestSet and perform the ambient mode exposuretest described in paragraph I.3. If the reading obtained without the filter isgreater than specification, a filter change willnot correct the malfunction and the shuttermust be replaced.4. If the exposure reading is between +0.2 and-0.1, the camera will produce correct expos-ures with no photocell filter but a filter mustalways be in place since the photocell opening- --.

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FAULT ANALYSIS CHART NO.1DARK-SLIDE-EJECT FUNCTION

c..J: :> .01-:I:UV)~V l U JU10CI..J" ' : : >;x :0.:1:Z'": l U J0:00::;..,j(/): l " ; '0-_a:~d;"0c: O U J1->0022

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FAULT ANALYSIS CHART NO.2EXPOSURE FUNCTION

PRESS RELEASE BUTTON MOTOR RUNS, SHUTTER BLADES CLOSE,. OPEN, CLO_SE, FILM EJECTS, BLADESOPEN (MIRROR MOVES CORRECTLY)CAMERA FUNCTION OK, PARTIAL CYCLE NO CYCLESEE CHART #3

Il ,CHECK FOR ELEC. CHECK REMOTENOISE FROM MOTOR . CONNECTORW/RELEASEOK I BAD 1 OK I BAD~ iCHECK FOR GEAR CHECK RELEASE CHECKTRAIN LOADING BUTTON CONNECTIONS ATSUBSTRATEOK I BAD OK I BAD OK I BAD1

CHECK CONTACT RESOLDERFROM S' TORELEASE BUTTON CON NECTI ONSTESTOK I BAD OK BAD

l 1REPLACE RECHECK j CHANGESUBSTRATE SUBSTRATE

_

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FAULT ANALYSIS CHART NO.3EXPOSURE FUNCTION

ALL EXPOSURE READINGSMAKE EXPOSURE TEST ACCEPTABLE

GOOD EXPOSURE OVER EXPOSURE UNDER EXPOSURE NO EXPOSURE TIMES OUT ORSEE CHART #4 SLOW FAST VERY LONGEXPOSURE

l l lMAKE SUREr'M WHEELNORMALj _

EXAMINE OPTICAL PATH

J ~ ~FIL TER CHANGE CHANGEONLY SUBSTRATEYES NO

I EXAMINEPHOTOCELLOPTICAL PATH~, OK BAD

CHECK FILTER ANDTRACKINGPOSS!~LE I IMPOSSIBLE

_j ~ADJUST FIL TE R REPAIR OR REPLACEAND TRACKING REPLACE SHUTTER SUBSTRATE

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SX-70 Darkslide Troubleshooting

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