ARMY  TM  5-6675-238-14 MARINE CORPS TM 08839A-14/1 Legend  for  figure  8-10  -  Continued 106. 107. 108. 109. 110. 111. 112. 113. 114. Lockwasher Washer Rectifier CR1 Voltage regulator A7 clamp Capacitor C1 Screw Lockwasher Terminal lug 115. 116. 117. 118. 119. 120. 121. 122. 123. Screw Washer LockWasher Nut Resistor R4 Rectifier CR2 Screw Capacitor Transistor  Q1 (1) (2) (3) (4) Open  lamp  assembly  cover  (5). Remove two screws (6) and washers (7) secur- ing lamp support (12); allow lamp support to hang loosely. Identify  and  unsolder  each  photocell  small color-coded  wire  from  terminal  board  TB2 (89, figure 8-10, sheet 2) terminals 1 thru 10. Remove two screws (13, figure 8-10, sheet 1) securing photocell assembly (2) to lamp sup- port; remove photocell assembly, b. Replacement. (1) (2) (3) (4) (5) Carefully  install  photocell  assembly  (4)  on lamp support (12) and secure with two screws (13). Identify and solder each photocell color-coded wire to terminal board TB2 (89, figure 8-10, sheet 2). See tape reader schematic diagram (figure  FO-19)  for  location  of  each  color-coded wire on terminal board TB2. Secure lamp support (12, figure 8-10, sheet 1) with two screws (6) and washers (7). Visually align lamps with photocell assembly, Position lamp  support  so  that  clearance  from  lamp assembly  to  photocell  assembly  is  0.035  to 0.045 inch. Close lamp assembly cover (5). Perform photocell amplifier A1 bias adjust- ments in accordance with procedure in table 8-8, test 5.3. 8-28. Plug-In Circuit Card A1, A2, A3, A4, A5, A6, or A7 Removal and Replacement.  See figure 8-10, sheet 2, and remove and replace photocell amplifier Al (57) as follows: a. Removal  Carefully  pull  photocell  amplifier  A1 (57)  out  of  the  card  cage  using  handle  on  top  of photocell  amplifier  A1. When  installing  a  plug-in  circuit  card, check  that  it  is  the  proper  card  for  the respective receptacle. Check that the card is properly aligned during installation or damage  to  connector  or  receptacle  may result. b. Replacement. Install photocell amplifier A1 (57) in card guides and slide inward to engage connector. 8-29. Servo Feedback Potentiometer R2 or R3 Re- moval and Replacement.  See figure 8-10, sheet 2, and remove and replace servo feedback potentiometer R2 (65)  as  follows: a. Removal. (1)  Tag  and  unsolder  wires  from  servo  feedback potentiometer  R2  (65). (2) Loosen two setscrews securing servo feedback potentiometer R2 shaft to sensing arm drum assembly. (3) Remove three screws (66), washers (68), lock- washers (67), and clamps (69) securing servo feedback  potentiometer  R2  (65)  to  bracket support; remove potentiometer R2. b. Replacement. (1) (2) (3) (4) Secure  servo  feedback  potentiometer  R2  (65) to  bracket  support  with  three  screws  (66), washers  (68),  lockwashers  (67),  and  clamps (69). Align position of potentiometer for free movement of bearings allowing tape sensing arm to swing parallel to the front panel. Tighten two setscrews securing servo feedback potentiometer R2 shaft to sensing arm drum assembly. Solder wires to potentiometer. Adjust  servo  feedback  potentiometer  R2  in accordance with procedure in table 8-8, test 3. 8-101