TM 1-1500-204-23-4 support  on  direct  exchange  basis.    TM  11-6140-203-23 provides    instructions    for    the    proper    maintenance    of aircraft nickel-cadmium batteries. NOTE If     the     battery     being     replaced exhibited any signs of overheating   or   overcharging   (e. g.,  fumes  or  vapor  coming  from the vent tubing, free electrolyte is present    inside    the    case,    etc.) adjustment of the voltage regulator should be checked/adjusted    in    accordance with applicable maintenance manual. (2)  Cleaning.    Clean  battery  in  accordance with TM 11-6140-203-23.  Clean battery compartment in accordance with TM 1-1500-344-23. b.     Relays.      Army   aircraft   use   generator   field, reverse   current,   bus   control,   non-essential   bus,   and electronic/solid state relays.  Relays are used for remote control  of  circuits  carrying  heavy  currents.    Two  relay types are shown in figure 3-8. (1)  Inspection.    Inspect   contact   points   for corrosion. (2)   Replacement   criteria.      Replace   when contact points are corroded beyond depth of pin plating. c.  Inverters.  Inverters, as shown in figure 3-9, are sometimes   used   to   convert   aircraft   dc   power   to   ac power.    The  ac  power  is  mainly  used  for  instruments, radios, radar, lighting, weapons, and other accessories. (1)  Types.    There   are   two   basic   types   of inverters:  the  rotary  and  the  static.    Either  type  can  be single phase or multiphase. (2)  Inspection.    Use  the  applicable  aircraft maintenance manual for inspection of inverters. General inspection procedures are as follows: (a) Inspect case for cracks or damage. (b)   Inspect   electrical   connectors   for broke pins or cracked connector inserts. (c)   Check   for   bonding   and   security mounting. (d) Check for faulty operation. (3)   Adjustment.      Usually,   no   adjustments can be made. (Refer to TM 11-6130-385-34). Figure 3-8.  Typical Relays Change 3   3-14