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KV-21FE13 / 21FE13C / 21FM13 / 21FM13C
SAFETY CHECK-OUT
After correct ng the or g nal serv ce problem, perform the follow ng
safety checks before releas ng the set to the customer:
1. Check the area of your repa r for unsoldered or poorly soldered
connect ons. Check the ent re board surface for solder splashes and
br dges.
2. Check the nterboard w r ng to ensure that no w res are “p nched” or
touch ng h gh-wattage res stors.
3. Check that all control knobs, sh elds, covers, ground straps, and
mount ng hardware have been replaced. Be absolutely certa n that
you have replaced all the nsulators.
4. Look for unauthor zed replacement parts, part cularly trans stors,
that were nstalled dur ng a prev ous repa r. Po nt them out to the
customer and recommend the r replacement.
5. Look for parts wh ch, though funct on ng, show obv ous s gns of
deter orat on. Po nt them out to the customer and recommend the r
replacement.
6. Check the l ne cords for cracks and abras on. Recommend the
replacement of any such l ne cord to the customer.
7. Check the B+ and HV to see f they are spec fi ed values. Make sure
your nstruments are accurate; be susp c ous of your HV meter f sets
always have low HV.
8. Check the antenna term nals, metal tr m, “metall zed” knobs, screws,
and all other exposed metal parts for AC leakage. Check leakage
as descr bed below.
Leakage Test
The AC leakage from any exposed metal part to earth ground and from
all exposed metal parts to any exposed metal part hav ng a return to
chass s, must not exceed 0.5 mA (500 m croamperes). Leakage current
can be measured by any one of three methods.
1. A commerc al leakage tester, such as the S mpson 229 or
RCA WT-540A. Follow the manufacturers’ nstruct ons to use these
nstruct ons.
2. A battery-operated AC m ll ampmeter. The Data Prec s on 245 d g tal
mult meter s su table for th s job.
3. Measur ng the voltage drop across a res stor by means of a VOM
or battery-operated AC voltmeter. The “l m t” nd cat on s 0.75 V,
so analog meters must have an accurate low voltage scale. The
S mpson’s 250 and Sanwa SH-63TRD are examples of pass ve VOMs
that are su table. Nearly all battery-operated d g tal mult meters that
have a 2 VAC range are su table (see F gure A).
How to Find a Good Earth Ground
A cold-water p pe s a guaranteed earth ground; the cover-plate reta n ng
screw on most AC outlet boxes s also at earth ground. If the reta n ng
screw s to be used as your earth ground, ver fy that t s at ground
by measur ng the res stance between t and a cold-water p pe w th an
ohmmeter. The read ng should be zero ohms.
If a cold-water p pe s not access ble, connect a 60- to 100-watt trouble-
l ght (not a neon lamp) between the hot s de of the receptacle and the
reta n ng screw. Try both slots, f necessary, to locate the hot s de on the
l ne; the lamp should l ght at normal br ll ance f the screw s at ground
potent al (see F gure B).
To Exposed Metal
Parts on Set
0.15 F 1.5 K ΩAC
Voltmeter
(0.75 V)
Earth Ground
Trouble L ght
AC Outlet Box Ohmmeter
Cold-water P pe
F gure A. Us ng an AC voltmeter to check AC leakage. F gure B. Check ng for earth ground.
