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KV-20/13VM30/31
RM-Y138/W
SAFETY CHECK-OUT
(US Model only)
After correcting the original service problem, perform the
following safety checks before relasing the set to the customer
1. Check the area of your repair for unsoldered or poorly
soldered connections
Check the entire board surface for
solder splashes and bridges.
2. Check the interboard wiring to ensure that no wires are
"pinched" or contact high-wattage resistors.
3. Check that all control knobs, shields, covers, ground straps,
and mounting hardware have been replaced. Be absolutely
certain that you have replaced all the insulators.
4 Look for unauthorized
replacement
parts, particularly
transistors, that were installed during a previous repair Point
them out to the customer and recommned their replacement
5 Look for parts which, though functioning, show obvious signs
of deterioration
Point them
out to the customer
and
recommend their replacement
6. Check the line cord for cracks and abrasion. Recommend the
replacement of any such line cord to the customer
7. Check the condition of the monopole antenna (if any).
Make sure the end is not broken off and has the plastic cap on
it.
Point out the danger of impalement on a broken antenna to
the customer, and recommend the antenna's replacement.
8. Check the B+ and HV to see they are at the values specified .
Make sure your instruments are accurate; be suspicious of
your HV meter if sets always have low HV
9. Check the antenna terminals, metal trim, "metallized" knobs,
screws, and all other exposed metal parts for AC leakage
Check leakage as described below
LEAKAGE TEST
The AC leakage from any exposed metal parts to earth ground
and from all exposed metal parts to any exposed metal parts
having a return to chassis, must not exceed 0.5 mA(500
microampers)
Leakage current can be measured by any one of
three methods.
1. A commercial leakage tester, such as the Simpson 229 or
RCA WT-540A.
Follow the manufacturers instructions to use
these instruments
2. A battery-operated AC milliammeter The Data Precision 245
digital multimeter is suitable for this job
3. Measuring the voltage drop across a resistory by means of a
VOM or battery-operated AC voltmeter The "limit" indication
is 0 75V, so analog meters must have an accurate low-voltage
scale The Simpson 250 and Sanwa SH-63TRD are examples
of a passive VOM that is suitable
Nearly all battery operated digital multimeters that have a 2V
AC range are suitable (See Fig A)
HOW TO FIND A GOOD EARTH GROUND
A cold-water pipe is guaranteed earth ground, the cover plate
retaining screw on most AC outlet boxes is also at earth ground
If the retaining screw is to be used as your earth ground, verify
that it is at ground by measuring the resistance between it and a
coldwater pipe with an ohmmeter. The reading should be zero
ohms. If a cold-water pipe is not accessible The reading should
be zero ohms. If a cold-water pipe is not accessible, connect a
60-100 watts trouble light (not a neon lamp) between the hot side
of the line, the lamp shojuld light at normal brilliance if the screw
is a ground potential (See Fig. B)
To Exposed Metal
Parts on Set
AC
A
voltmeter
(0 75V)
0 15uF
=
Earth Ground
Fig A Using and AC voltmeter to check AC leakage
Trouble Light
AC Onictnee
COE!
Cold-water Pipe
Fig B Checking for earth ground
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