KDL-46XBR10, KDL-52XBR10 - Sony TV Service Manual (repair manual). Page 7

KDL-46/52XBR10 (UC)     6

After correcting the original service problem, perform the 
following safety checks before releasing 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 touching 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 recommend 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 cords for cracks and abrasion. Recommend the 

replacement of any such line cord to the customer.  

 
7.  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 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 instructions. 

2.  A battery-operated AC milliampmeter. 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” 
indication is 0.75 V, so analog meters must have an accurate 
low voltage scale.

 

The Simpson’s 250 and Sanwa SH-63TRD are examples of 
passive VOMs that are suitable. Nearly all battery-operated 
digital multimeters that have a 2 VAC range are suitable (see 
Figure A).

How to Find a Good Earth Ground
A cold-water pipe is a 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 cold-
water pipe with an ohmmeter. The reading should be zero ohms.

If a cold-water pipe is not accessible, connect a 60- to 100-watt 
trouble- light (not a neon lamp) between the hot side of the 
receptacle and the retaining screw. Try both slots, if necessary, 
to locate the hot side on the line; the lamp should light at normal 
brilliance if the screw is at ground potential (see Figure B).

Trouble Light

AC Outlet Box

Ohmmeter

Cold-water Pipe