Parts Inspection - Hammarlund SP-600-JX-21 Handbook

T.O. 31R2
J.
Shake out loose metal and other particles. Make
sure none remain wedged in the assembly. Look closely
for metal or other foreign matter, especially between the
stator and rotor plates of the variable air trimmer capaci-
tors. Mesh all trimmer capacitors, checking for even
meshing and spacing between plates.
L-
e. Carefully check bakelite and melamine boards for
scratches and cracks; make sure isolantite bases, insula-
tor feed-throughs, and crystal porcelain holders are not
minutely cracked or chipped.
f. Check multiple coil assemblies mounted on the
same form for spacing. Make sure the start and finish
leads on all coil assemblies are properly connected. Check
each coil for continuity and for broken strands. Check
for nicks or scratches on coils and chokes, also check to
see that the fungicidal varnish coating is not punctured.
g.
Check the possibility of the parts of the sub-
assembly shorting to other subassemblies or to the
receiver chassis, when assembled. Make sure the pilot
lamps, meter board, etc mount rigidly.
h. Check to see that the metal finish on each of the
plated parts contained in the subassembly has the proper
finish. Check to see that any excessive fraying of wire
insulation is cut off and touched up with insulation
compound (varnish), Specification MIL-C-13811.
6-1 Q. PARTS INSPECTION.
6-11. For purposes of receiver overhaul, each part con-
-
tained in the receiver, when removed, may be inspected
in accordance with the applicable procedures outlined
below. When a part fails to meet any one of the con-
siderations listed for it, reject it; but in instances where
the part only requires cleaning have it cleaned prior to
reinspection. All repaired parts must be reinspected prior
to use.
6-12. ELECTRON TUBE INSPECTION. To inspect
each of the electron tubes in the receiver, remove the
tube shield, if any, and in the instance of two of the
tubes remove the top-hat type of tube retainer associated
with each.
a. Check the firmness of each tube in its socket. Press
the tube into the socket, exerting only normal pressure.
When the tube is properly seated it should be held firmly
in place, as evidenced by feel.
b. Let the tubes cool off before removing them from
their sockets in the receiver. Use the appropriate tube
remover to remove miniature tubes; also, straighten the
lniniature tube pins in the appropriate pin straightener
before trying to insert the miniature tube into its socket.
- ,
When inserting the miniature tube do so with the top
-
of the tube socket visible so that the tube pins may be
properly aligned in relation to the socket.
c.
Inspect the glass envelope of each tube for dirt;
also check to see that the tube envelope is not loose.
Make sure that miniature tube pins are not loose or
broken, being careful not to bend the pins during removal
or insertion of the miniature tube. Check to see that the
gliiss
envelope is not chipped
; ~ t
the pins.
Section VI
Paragraphs 6-10
to
6-16
6-13. RESISTOR INSPECTION. Apart from the vit-
reous-enameled bleeder resistors R85, R72, and R73 in
the B+ rectifier supply, which are of the usual lug type
and rated respectively at 10, 20, and 20 watts, all the
resistors in the receiver are of the pigtail, fixed composi-
tion insulated type, rated at
1/2,
1/3 or
1
watt.
a. Inspect the coatings of R85, R72, and R73 for
signs of cracking and chipping, especially at the ends
of each.
b. Examine the body of each resistor for blistering,
discoloration, and breaks caused by overheating.
c. Inspect all resistor leads for dirt, dust, corrosion,
and looseness. Check the security of all mountings. Once
a resistor of the pigtail type is unsoldered, do not re-use
if the leads were initially cut short since the point of
entry of the lead may be partially or completely broken.
Also, the heat applied during unsoldering and resolder-
ing may damage the resistor or change its value.
6-14. AIR-DIELECTRIC VARIABLE CAPACITOR
INSPECTION.
a. Inspect the capacitor for dust, dirt, lint, and poor
or broken soldering.
b. Inspect the capacitor plates for visible damage such
as nicks and bending. Also, by meshing the rotor and
stator plates, make sure that during meshing the plates
do not touch and that they remain reasonably centered
at all times with regard to plate spacing.
Never tamper with the plates of the main tun-
ing capacitor.
c. Inspect the capacitor plate mountings, terminals,
and overall for looseness, wear, breaks, or other damage.
Make sure that the main capacitor ball bearings and the
trimmer capacitor rotor spring assembly in each instance
provide for smooth, firm rotor and stator meshing.
6-15. PIGTAIL-LEAD CAPACITOR INSPECTION.
a. Inspect each pigtail-lead type capacitor for lead
looseness. Do this by applying a firm steady pull to each
capacitor lead in turn, making sure that the tension
applied is not excessive.
b. Inspect each capacitor for discoloration, breaks,
chipping, and evidence that the molded casing does not
completely enclose the capacitor assembly.
c. Inspect the three oil-filled, tubular, metal-case
capacitors (C137, C144, and C163) for evidence of oil
leakage at the pigtail-lead solder terminal connections,
for the quality of the solder terminals, and for corrosion.
6-16. TERMINAL-TYPE CAPACITOR
INSPECTION.
a. Inspect the capacitor terminals for insulation cracks,
looseness, corrosion, and evidence of leakage of elec-
trolyte in the case of dry electrolytic capacitors.
b. Inspect the metal case container of each unit for
bulges, dents, cracks, and other damage of any kind.
Make sure the terminal lugs on the three-section elec-
trolytic capacitor (CIGIA, B, C) are not loose.