Polaroid Joshua Captiva, Service Manual

Page: 22 / 134

1 - 16
Drive and Switching Systems
You will note similarities between some of the components of the Joshua drive system shown in Figures 1-
15 and 1-16, and comparable parts of Spectra/Image, 640, Impulse and SX-70 drives — for example,
motor-driven reduction gear train, single-revolution timing gear with cammed surfaces, counter wheel, pick
assembly and wireform switches.
However, many Joshua drive system parts are new and unique. These include:
• Recock Link, one-way wrap-spring Clutch Gear and Recock Latch system for positioning and
returning the Taking Mirror.
• Viewfinder Blind system which prevents stray light from striking the film during exposure.
• Motor operation in both forward and reverse directions.
• Film frame transport via two pick systems and two sets of rollers. One pick pulls the frame into the
feed rolls which drive it through the “chute”, and a second pick moves the frame into the storage
chamber as it exits the spread system rollers.
• Separate wireform switchblocks for logic functions and powering the camera:
- A 5-wire “Logic” switch (Figure 1-15) on the gear train side of the drive assembly controls
Electronic Trim, Chamber Full, Self-Timer, End of Pack, Darkslide/ End of Cycle, Shutter
Release and Film Speed functions.
- A separate 3-wire “Erect” (Power) switch (Figure 1-20) located on the opposite side of the
mainframe controls B+, VER and GND lines, and operates in conjunction with the Door Latch
Sensor, Erect Sensor, Power Actuator and Film Shade.
Logic Switch (See Switch Block Assembly in Figure 1-16) Power On at Start of Processing (Camera Erect)
Figure 1-15. Logic Switch and Power On switch