ARMY TM 5-6675-238-14 MARINE CORPS TM 08839A-14/1 (a) Tag and unsolder wires from power supply PS3 (110) terminals. (b) Remove six screws (106), washers (108), and lockwashers  (107);  remove  power  supply PS3  (110)  from  power  supply  assembly (109), NOTE Spread heat conductive sealing compound (340 or G641) on back of power supply before  installing. (2) Replacement. (a)  Install  power  supply  PS3  (110)  on  power supply assembly (109) and secure with six screws (106), washers (108), and lockwashers (107). (b)  Solder  wires  to  power  supply  PS3  (110) terminals. d. Overvoltage  Protector  Z1,  Z2,  Z3,  or  Z4.  Re- move and replace overvoltage protector Z2 (116, figure 8-6, sheet 4) as follows: (1) Removal. (a)  Tag  and  unsolder  wires  from  overvoltage protector  Z2  (116)  terminals. (b) Remove  two  screws  (119),  washers  (117), and lockwashers (118); remove overvoltage protector Z2 (116) from power supply as- sembly  (109). NOTE Spread heat conductive sealing compound (340  or  G641)  on  back  of  overvoltage protector   before   installing. (2) Replacement. (a)  Install  overvoltage  protector  Z2  (116)  on power  supply  assembly  (109)  and  secure with screws (119), washers (117), and  lock- washers  (118). (b) Solder  wires  to  overvoltage  protector  Z2 (116) terminals. 8-23.   Signal   Processor   Unit   Adjustments.   The   SPU adjustments consist of adjusting four modular power supplies to their specified trip voltage, and logic no. 2 electronic  component  assembly  A2  adjustments,  Adjust- ments of the modular power supplies and logic no. 2 electronic  component  assembly  A2  should  be  checked every 90 days or sooner if indicated by the self-test procedure. The overvoltage protectors are normally not adjusted  unless  a  malfunction  is  suspected.  If  an  over- voltage  protector  is  replaced,  the  new  one  must  be adjusted before the SPU wires are soldered to its termi- nals. Connect cable W201 to 115-VAC power, cable W203 to the tape reader, cable W204, and cable W209 as shown in figure 8-2. See figures 8-7, 8-8, and 8-9 for location  of  adjustments  and  test  jacks  and  perform adjustment procedures in accordance with the following paragraphs. Blue bus terminals W1 and W2 contain 115-VAC. a. Modular  Power  Supply  PSI  Voltage  Adjustment. Perform voltage adjustment of modular power supply PS1 as follows: (1) Connect digital voltmeter (DVM) test leads to +28V and RTN test jacks, (2) Press SPU ON switch-indicator to on (switch- indicator  lights). NOTE Prior to making voltage adjustments, take cover  off  the  adjustment  screw. (3)  Adjust  modular  power  supply  PS1  voltage adjustment for +28 (±1)V. (4)  Place  cover  back  on  adjustment  screw  and disconnect  DVM  test  leads. (5) Press SPU ON switch-indicator to off (switch- indicator  goes  out). b. Modular  Power  Supply  PS2  Voltage  Adjustment. Perform voltage adjustment of modular power supply PS2 as follows: (1)  Connect  DVM  test  leads  to  +  5V  and  RTN test jacks. (2) Press SPU ON switch-indicator to on (switch- indicator  lights). (3)  Adjust  modular  power  supply  PS2  voltage adjustment for + 5 (±0.04)V. (4) Press SPU ON switch-indicator to off (switch- indicator  goes  out), (5)  Disconnect  DVM  test  leads, c. Modular  Power  Supply  PS3  Voltage  Adjustment. Perform voltage adjustment of modular power supply PS3 as follows: (1) Connect DVM test leads to + 15V and COM test jacks. (2) Press SPU ON switch-indicator to on (switch- indicator  lights). (3)  Adjust  modular  power  supply  PS3  voltage adjustment  for  +  15  (±0.04)V. 8-94