TM 1-1500-204-23-4 Figure 4-6.  Jetcal Tester · Establish   the   proper   relationship between the EGT and engine rpm on   engine   runup   during   tabbing (micing)   procedures   by   the   rpm check  (takcal)  and  potentiometer in  the  jetcal  analyzer.    (Tabbing procedures  are  those  procedures followed     when     adjusting     fixed exhaust nozzle exit areas.) · Check aircraft fire detector, overheat  detector,  and  wing  anti- icing   systems   by   using   tempcal probes. WARNING Drycleaning  solvent  is  flammable and solvent vapors are toxic.  Use P-D-680, Type II Solvent in a well- ventilated  area.    Keep  away  from open   flames.      Avoid   prolonged solvent contact with skin. (2) Cleaning.  Clean jetcal tester with a cloth moistened in drycleaning solvent, Federal Specification P-D-680, Type II, and wipe dry with a dean cloth. (3) Operating procedures.  Refer to step-by- step  procedures  on  the  instruction  plate  of  the  jetcal tester. (4) Safety practices.  Observe the following safety practices while operating the jetcal analyzer: · Never    use    a    volt-ohmmeter    to check the potentiometer for continuity.    If  a  volt-ohmmeter  is used, damage to the galvanometer and standard battery cell will result. · Check  the  thermocouple  harness before  engine  runup.    This  must be done because the circuit must be correct before the thermocouples   can   be   used   for true EGT pick up. · For     safety,     ground     the     jetcal analyzer when using an ac power supply.    Any  electrical  equipment operated on ac power and utilizing  wire-wound  coils  such  as the probes with the jetcal analyzer,  has  an  induced  voltage on the case that can be discharged if the equipment is not grounded.    This  condition  is  not apparent  during  dry  weather,  but on  damp  days  the  operator  can be   shocked   slightly.      Therefore, for protection of the operator, the jetcal analyzer should be grounded using the pigtail lead in the power inlet cable. 4-8