MHC-NX1, MHC-NX3AV, STR-NX1, STR-NX3 - Sony Audio Service Manual (repair manual). Page 3

3

1.5 k

Ω

0.15 

µ

F

AC
voltmeter
(0.75 V)

To Exposed Metal
Parts on Set

Earth Ground

After correcting the original service problem, perform the follow-
ing safety check before releasing the set to the customer:
Check the antenna terminals, metal trim, “metallized” knobs,
screws, and all other exposed metal parts for AC leakage.
Check leakage as described below.

The AC leakage from any exposed metal part to earth ground and
from all exposed metal parts to any exposed metal part having a
return to chassis, must not exceed 0.5 mA (500 microamperes).
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 resistor by means of a

VOM or battery-operated AC voltmeter. The “limit” indica-
tion is 0.75 V, so analog meters must have an accurate low-
voltage scale. The Simpson 250 and Sanwa SH-63Trd are ex-
amples of a passive VOM that is suitable. Nearly all battery
operated digital multimeters that have a 2 V AC range are suit-
able.  (See Fig. A)

MODEL

PART No.

NX1: AEP, UK and Korean models

4-221-391-0[]

NX1: US and Canadian models

4-221-391-1[]

NX1: Malaysia, Singapore, Thai and

Tourist models

4-221-391-2[]

NX3: AEP, UK, Korean and Australian models

4-221-391-3[]

NX3: US and Canadian models

4-221-391-4[]

NX3: Malaysia and Singapore models

4-221-391-5[]

PART No.