TM 55-4920-402-13&P Symptoms IPS and clock angle readings not repeatable;  i.e., restoring  weights to original condi- tion does not give same readings. False reading on Balancer’s  IPS meter. Table  3-1.  Troubleshooting  -  Continued Probable Cause Polarity  of  Magnetic  Pickup  incorrect. Magnetic Pickup Cable plugged into Magnetic  Pickup  backwards  (wrong polarity). RPM RANGE switch set to wrong range. Mechanical  components  on  rotor  are faulty, Bearings, dampers, rod-ends, etc.,  should  all  be  rechecked. When the Balancer’s RPM TUNE dial is set below 100 (on any RPM RANGE) the  circuitry  is  unstable  and  causes false readings on the IPS meter. Remed y Puke  should  first  go  negative,  then  sharply  posi- tive where Phazor triggers, then go negative to zero. Check  that  indexing  key  is  correctly  lined  up. It is not easy, but it can be plugged in backwards. Set RPM RANGE to Xl for mam rotor. Correct or replace faulty components. DO NOT USE BALANCER WITH RPM TUNE DIAL SET BELOW 100. a.  Connect  VIBREX  to  helicopter  28  vdc  power 3-12. Removal of VIBREX from Aircraft. The VIBREX source and perform the field operational checkout in         is removed from the aircraft as follows: paragraph 3-8. This will isolate if the Balancer unit, Strobex,  Accelerometers  or  Magnetic  Pickup,  plus a. Disconnect 28 vdc power cable. cables are at fault. b.  Disconnect  signal  cables  from  VIBREX. b. After performing step a, and the VIBREX is still c. Place Balancer and Strobex units in their proper not  operative,  refer  to  Chapter  4,  Aviation  Interme- locations  in  the  Carrying  Case. diate Maintenance Instructions, for bench testing d.  Remove  Cables,  Accelerometers,  Magnetic  Pickups, of the VIBREX. and Brackets, and place in Carrying Case. Section  IV.  INSPECTION  AND  SERVICE 3-13. Inspection.  Table 3-2 provides a general guide for inspection of the VIBREX. The inspection should be performed after each use and prior to storage. Item Outside  surfaces Controls  and switches Cables Table 3-2. Inspection Chart Condition Inspect for scratches, chips, dents, cracks,  or  missing  hardware. Inspect  for  loose  knobs,  binding controls, or cracked meter. Inspect cables for breaks, bent or broken pins, or other damage. Remedy Repair,  repaint,  or  replace  as necessary. Tighten  setscrews  in  knobs,  or repair  or  replace  parts  as  necess- sary. Repair  or  replace  as  necessary. Change 4 3-11