vered and corrected before they result in seri-
Table 4-1. Daily Preventive Maintenance Checks
ous damage or failure. The necessary preven-
tive maintenance checks and services to be per-
ITEM TO BE INSPECTED
formed are listed in tables 4-1,4-2, and 4-3. The
item numbers i n d i c a t e the sequence of
Clean the interphone test set case,
minimum inspection requirements. Defects dis-
cover, and front panel. Cleaning
instructions are contained in para-
covered during operation of the unit will be
noted for future correction to be made as soon as
S W I T C H E S , INDICATORS, AND
operation has ceased. Stop operation im-
mediately if a deficiency is noted during opera-
a. Check switches, indicators, and
tion which would damage the equipment. Re-
binding posts for loose or insecure
fastenings; tighten if required.
cord all deficiencies together with the corrective
b. Switches should operate smoothly
action in accordance with the procedures con-
and knobs should be properly se-
tained in TM 38750.
cured to shafts and should not
bind. Tighten loose knobs and be
sure they do not rub against the
panel. Replace broken or defec-
Checks and Services
Organizational preventive maintenance checks
and services consist of daily preventive mainte-
The KEYING and SIGNAL
nance checks and services, intermediate pre-
ventive maintenance checks and services, and
switches and normally are in
periodic preventive maintenance checks and
the midposition and METER
a. Daily Preventive Maintenance Checks and
During operation be alert for any
Services. Perform the maintenance functions
evidence of unusual performance;
check for burned-out lamps and
indicated in the daily preventive maintenance
fuses. Tap switches while observ-
ing meter indications for erratic
checks and services that must be performed
daily or under the conditions listed below.
Table 4-2. Intermediate Preventive Maintenance Checks and
(1) When the equipment is initially re-
ITEM TO BE INSPECTED
(2) When the equipment has been returned
after higher category maintenance.
(3) At least once each week if the equipment
Check to see that the unit is complete.
is maintained in a standby condition.
CABLES AND CONNECTORS
Check the power and test cables for
cuts, kinks, and frayed insulation.
Checks and Services. The maintenance func-
Repair as necessary. Refer to
tions indicated in the intermediate preventive
higher level of maintenance for
replacement of cables.
maintenance checks and services table (table
HINGES, HANDLES, FASTENERS,
4-2) are performed once each intermediate in-
terval in addition to the daily preventive
SCREWS AND COVER GASKETS
maintenance checks and services (table 4-1). An
a. Hand-check hinges, handles,
intermediate interval is defined as approxi-
fasteners and front panel mount-
ing screws for looseness;
mately 30 calendar days of an 8-hour-per-day
tighten if possible; otherwise,
operation. Adjustment of the maintenance in-
refer to higher level of mainte-
terval must be made to compensate for any un-
nance for repair or replacement.
usual operating conditions. Equipment main-
b. Check cover gasket for cracks or
tained in a standby (ready for immediate opera-
of maintenance for replacement.
tion) condition must have intermediate mainte-
nance performed. Equipment in limited storage
Check the exterior metal surfaces of
(requires service before operation) does not re-
the interphone test set case, cover,
quire intermediate maintenance.
and front panel for rust or cor-