Figure 19. C-2298 VOLUME control and MONITOR switch.
Instead of crew person audio accessories (AVC, CVC, or H-161/U), a handset (H-189
or H-250) may be used to initially check the operation of the intercom set.
(Reference made to handset means audio accessory.) Make sure the handset is good
and its audio plug contacts are clean.
Before connecting cables and audio accessories to components of the intercom set,
make sure that all plug and jack contacts and pins are clean and undamaged. After
connecting, ensure that the connections are tight.
d. Verify operation of handset H-189/U (H-250U). See Figure 20. To verify that the handset
H-189/U (H-250/U) is good, make the following checks using test set AN/PSM-45:
(1) Phone element check. Set up test set for ohms checks and circuit disturb between pins A
and B by placing one test meter lead on pin A and tapping pin B with the other test lead. A clicking
sound should be heard from the phone element if it is good.
(2) Keying circuit check. Connect one meter test lead to pin A, and place the other meter test
lead on pin C of the handset audio plug. With the handset PUSH-TO-TALK (PTT) switch held in, the
meter display should show 0