PRODUCT No.
3900 ME Disassembly Procedure 1. Self-timer charge lever assembly (0-A118)—Self-timer screw left-handed (A122) — 231K-H50 2. Body Covering, left and right (A19, A20) 3. Install self-timer lever assembly (0-A118) temporarily. 4. Bottom cover assembly (A400) — CSS 1.7 x 2.8 x 3 Connector seat (A23), R button (C117) 5. Winding lever assembly (0-C69) Cover screw (C139) — 23600K-C135-A (left handed) Winding lever nut (C8) — 23600K-C134-A2 Cover ring (A321) 6.
19. Counter dial Back cover open Counter dial spring (C57) - Counter retainer plate (C25), Counter dial assembly (0-C34) Come off transporting claw spring (C65) Remove (C146) (C53) and CNS 1.7 x 3 Winding seat assembly (0-C2) - (0-C5) - (C7) 20. Shutter block (S000) - CNL-D 1.7 x 3 x 3 21. Bottom release assembly (0-C147) Winding up little from bottom part with tool (23900K-C207-A) To remove retainer screws of (0-C147). 22.
Assembly Procedure 1. Spool assembly (0-C204) and spool cam assembly (0-C202) W17 (t=0.2mm) 2. Top mec. Plate assembly (0-C1) Pulling back transport indicator 3. Sprocket shaft pin (C40) Apply screw lock on Set T 1.7 x 1.6 4. Winding shaft assembly (0-C22) - Main gear (C30) 5. Winding stopper assembly (0-C26) 6. Winding spring assembly (0-C12) Proper tension of the spring is shown in figure. After installing (0-C12), install (0-C106) and (C207) temporarily. - 23900K-C207-A 7.
11. Shutter block (E000) - CNL-D 1.7 x 3 x3 Light seal plate (A8) 12. Bulb actuator plate (A504) Temporary installation - CNL-D 1.4 x 2 13. Back cover assembly (A200) 14. Winding seat assembly (0-C2) - (C53), (C146), CNS 1.7 x 3 Install (0-C2) with back cover open Winding lever click cam assembly (0-C5) Winding lever friction spring (C7) Engage transporting claw spring (C65) 15. Counter transporting adjustment a) Check the function of counter dial stopper lever (C4) and transporting claw assembly (C18).
18. Cocked shutter assembly (0-C23) - SW actuator lever shaft. 19. Main SW adjustment = (I200) When shutter actuator plate is held in "ON" position, 0.2mm clearance is necessary between longer contact piece of main SW and insulation blue collar. To adjust the clearance, bend the shorter contact piece. When both contact pieces touch each other, and the shorter contact piece is pulled down, the longer one should be down also as the shorter one does.
b) LED indication adjustment High EV (EV12), EV16) Low EV (EV8) - VR-B VR-C c) Battery checker - VR-D 2.45V - Turning on and off (flickering) 2.55V - Turning on d) VR-E is prohibited to adjust 29. Counter indication (C15) - (A300) 30. Top cover (A131) - (A300) Set shutter dial at "B" Shutter restriction lever is set at left (viewing from back) Put on top cover softly and fix it turning shutter dial to AUTO position Four retainer screws Rewinding parts, shutter dial, winding lever, etc. 31.
34. Body covering, self-timer lever assembly (0-A118) Self-timer screw (A122) - left-handed. 35. Disassembly of front board and mirror housing a) Remove self-timer (H000) b) Mirror release lever (0-A111) c) Mirror housing d) Connector (I100) - only loosening (I2) e) Unsolder 5 lead wires Purple 2, orange 2, black 1 36. SWg, SWm located underneath mirror housing SWg = Magnet switch SWm = Memory switch a) SWg - Spring tension adjustment 8~10g spring tension is desirable: Check with tension gauge.
37. Adjustment of SWm and SWg Time lag sequence of SWm and SWg To check the time lag, an oscilloscope is necessary. The time lag is determined by the variation in voltage when SWm and SWg turn "ON" and "OFF". Here is one example for time lag check with a single-trace oscilloscope. Adapter should be made as shown below. Adapter is connected to mirror housing connector and oscilloscope.
PENTAX ME Notes and Troubleshooting Tips FIGURES: Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig.
ADJUSTMENT SEQUENCE: 1. Auto speeds Variable resistor A set: ASA 100, X1 compensation, f/8. With 2.8V supplied to the battery compartment, the shutter should deliver the following shutter speeds ath the indicated light levels: EV12 1/60 second EV16 1/1000 second EV8 1/4 second 2. Meter Readout EV 12 and 16 Adjust variable resistor B EV8 Adjust variable resistor C Later versions of the flex circuit board have only one meter readout adjustment, Fig. 8. 3.
10. Slide LED display out of focusing screen slot at wind-lever side 11. Lift out complete flex circuit (Underside of flex circuit may be glued to top of pentaprism) 12. Unsolder 5 leads form front-plate circuit board 13. Unsolder green wire and blue wire from power winder terminals 14. Rewind-side leatherette; peel back wind-side leatherette far enough to reach front plate screws 15. Cock shutter 16. Screw at top rear of mirror cage, wind-lever side 17. 4 front-plate screws 18.
TROUBLESHOOTING: Typical battery drain Meter: 1.7-2.0mA Shutter open: 10mA Behaviour with batteries Fastest speed only except at mechanical shutter settings Replacement parts Circuit board T100 and Seiko shutter E000 available from Pentsx only as complete modules; other parts available individually Troubleshooting steps for specific problems 1.
2. Auto-exposure erratic, shutter sometimes delivers mechanical speed only. Memory time lag Chattering in magnet switch Check the timing between the magnet switch and the memory switch by plugging the modified circuit board (Fig. 7) into the mirrorbox connector I100. Power the special circuit board with a 6V DC power supply. Then measure across the switch with an oscilloscope as you release the mirror-box.
4. Yellow - "Over" LED remains on, shutter delivers mechanical action only 5. White - LEDs work, shutter delivers mechanical action only 6. Blue - LEDs do not work, shutter delivers mechanical action only 7. Brown - LEDs work, shutter delivers mechanical action only 8. Black - LEDs do not work, shutter delivers mechanical action only Tips for troubleshooting without disassembly 1. If the camera jams, check to see if the LEDs remain on.
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