TM 55-4920-328-13 a. Check the operation of the suspect transmitter (11MT1 or 11MT2) as outlined in paragraph 58.  Alternately, an operational check may be performed on   the   system   level   by   substitution   of   the   suspect transmitter with another transmitter of like part number. b. Energize  the  METS    electrical  systems  as outlined in chapter 2, Preliminary Checkout Prior to Test paragraph.  Allow the specified 30-minute warm-up and stabilization period. c. Check  the  output  of  power  supply  4A12PS5, which must be 28+lv dc.  If there is no dc output at this component, check for the presence of 117v ac, 60 Hz at 4A12PS5-1 and -2. d. With   28v   dc   excitation   power   available   at 11P1-A   and   -D   and   at   11P2-A   and   -D,   interchange transmitters 11MT1 and 11MT2 to determine if the fault still exists in the suspect circuit. 5-30.  Oil Pressure System. Troubleshoot   the   oil   pressure   system   using   the circuit information shown in figure FO-13 and as follows: NOTE It    is    assumed    that    continuity    and    power voltage   levels   have   been   checked   prior   to accomplishment of the following. a. Check   the   suspect   pressure   transmitter   as outlined in paragraph 5-10. b. Check the switching circuits depicted in figure FO-27. c. Follow  the general procedural steps specified in paragraph 5-27. 5-31.  Engine Low Oil Pressure System. Troubleshoot  the  engine  low  oil  pressure  system using   the   circuit   information   shown   in   figure   FO-20, figure  5-35  and  check  the  suspect  pressure  switch  as outlined in paragraph 5-15. NOTE It    is    assumed    that    continuity    and    power voltage   levels   have   been   checked   prior   to accomplishment of the following. 5-32.  NI and NII Speed System. Since the speed system operates on a signal input from  a  tachometer  generator  (the  engine  output  shaft speed signal is proportional to frequency), no measurable  voltage  level  is  available  for  fault  isolation in the signal circuits to meters M2 and M3 on operator's panel assembly.  The vertical tape indicator input signal Is   in   the   form   of   a   0   to   5v   dc   analog   which   is measurable with a dc voltmeter.  Therefore, if an analog above 0v dc is available at 1A3-1W12P1-V and -U, and at   1W12P1-X   and   -W,   it   must   be   assumed   that   the applicable  circuits  through  engine  safety  unit  3A4  are intact.      The   signal   input   to   speed   monitor   chassis assembly   2A1   is   in   the   form   of   a   +   pulsed   signal proportional  to  6  times  the  tach  frequency.    The  speed monitor   chassis   assembly   may   be   isolated   from   the system  and  tested  by  the  self-test  function  of  the  unit. (Refer to chapter 2.)  It is recommended that the speed system calibration procedures be simplified as an aid in troubleshooting.    Check  for  approximately  2.5v  dc  af 4J1-M and -D, (services sub-module) observing polarity, to  isolate  a  faulty  monitor  alarm  assembly.    If  erratic signals   are   observed   on   the   speed   monitor   chassis assembly, clean the circuit board connector contacts as outlined  in  chapter  6.    If  this  action  does  not  clear  the trouble,    check    the    installation    of    each    tachometer generator    as    outlined    in    chapter    2.        Check    each tachometer  generator  by  the  substitution  method  if  the trouble persists, then replace the faulty component. Two six times (6X) multipliers are located in engine safety unit 3A4.  One each is used in each of the speed channels  to  provide  six  pulses  out  for  each  pulse  in. The three phase input from the tachometer is multiplied by   six   and   used   as   the   input   to   the   digital   speed indicator. Better resolution for conversion to engineering units is obtained due to the multiplication. The   tach-generator   output   at   100%   is   70   Hz. Using the input to the six times multiplier, the output to the  digital  indicator  would  be  420  Hz.    Utilizing  the  "K" factor   pre-set   of   2,381   as   the   multiplier,   the   output Indicated  on  the  digital  indicator  would  be  100.0.    The decimal point on the digital indicator is fixed. 5-33.  T55-L-7/11/712 Electrical Torque System (Using Avco Inverter P/N 211900). Proceed as follows: a. With   all   systems   connected   and   energized and   the   specified   warm-up   accomplished,   check   the current   and   frequency   output   of   the   inverter.      The current  must  be  557  +  2  ma  at  2K  Hz,  checked  as follows: (1) Remove    connector    PB    from    the    mating connector on the inverter. Change 4 5-31