DOWNLOAD Sony KDL-40NX720 / KDL-46NX720 / KDL-55NX720 / KDL-60NX720 (serv.man2) Service Manual ↓ Size: 15.47 MB | Pages: 62 in PDF or view online for FREE

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.

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. Follow the manufacturers’ instructions.

2.  A battery-operated AC milliampmeter. 

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. Nearly all 
battery-operated digital multimeters that have a 2 VAC range are 
suitable. (see Figure A)

Figure A. Use an AC voltmeter to check AC leakage.

The cover-plate retaining screw on most AC outlet boxes is at 

earth ground. Verify the AC outlet box retaining screw ground 

by connecting 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)

Figure B. Checking for earth ground.

Trouble Light

AC Outlet Box

The circuit boards used in these models have been processed using 
Lead Free Solder. The boards are identified by the LF logo located 
close to the board designation e.g. H1 etc [ see example ]. The 
servicing of these boards requires special precautions to be taken as 
outlined below. 

It is strongly recommended to use Lead Free Solder material in order to guarantee optimal quality of new solder joints.  
Lead Free Solder is available under the following part numbers : 

Due to the higher melting point of Lead Free Solder the soldering iron tip temperature needs to be set to 370 degrees centigrade.  
This requires soldering equipment capable of accurate temperature control coupled with a good heat recovery characteristics. 

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SWITCH

UNIT

CAMERA MODULE

HEM2

HLT2

TCON

LD

G4

BATL

WIRELESS

LAN CARD

SWITCH

UNIT

CAMERA MODULE

HEM2

HLT2

TCON

LD

G5

BATL

WIRELESS

LAN CARD

SWITCH

UNIT

CAMERA MODULE

HEM2

HLT2

TCON

G7

LD

G6

BATL

WIRELESS

LAN CARD

SWITCH

UNIT

CAMERA MODULE

HEM2

HLT2

TCON

G7

LD

G6

BATL

WIRELESS

LAN CARD