CPD-G220R, CPD-G220S - Sony Monitor Service Manual (repair manual). Page 4

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 B+ and HV to see if they are specifi ed values. Make sure 

your instruments are accurate; be suspicious of your HV meter if 
sets always have low HV.

8.  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 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” 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).

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

NEVER TURN ON THE POWER IN A CONDITION IN WHICH THE 
DEGAUSS COIL HAS BEEN REMOVED.

SAFETY REALTED COMPONENT WARNING!!

COMPONENTS IDENTIFIED BY SHADING MARK ! ON THE SCHEMATIC 
DIAGRAMS, EXPLODED VIEWS AND IN THE PARTS LIST ARE 
CRITICAL FOR SAFE OPERATION.  REPLACE THESE COMPONENTS 
WITH SONY PARTS WHOSE PART NUMBERS APPEAR AS SHOWN IN 
THIS MANUAL OR IN SUPPLEMENTS PUBLISHED BY SONY.  CIRCUIT 
ADJUSTMENTS THAT ARE CRITICAL FOR SAFE OPERATION ARE 
IDENTIFIED IN THIS MANUAL.  FOLLOW THESE PROCEDURES 
WHENEVER CRITICAL COMPONENTS ARE REPLACED OR 
IMPROPER OPERATION IS SUSPECTED.

NE JAMAIS METTRE SOUS TENSION QUAND LA BOBINE DE 
DEMAGNETISATION EST ENLEVEE.

ATTENTION AUX COMPOSANTS RELATIFS A LA SECURITE!!

LES COMPOSANTS IDENTIFIES PAR UNE TRAME ET PAR UNE 
MARQUE  SUR LES SCHEMAS DE PRINCIPE, LES VUES EXPLOSEES 
ET LES LISTES DE PIECES SONT D’UNE IMPORTANCE CRITIQUE 
POUR LA SECURITE DU FONCTIONNEMENT.  NE LES REMPLACER 
QUE PAR DES COMPOSANTS SONY DONT LE NUMERO DE 
PIECE EST INDIQUE DANS LE PRESENT MANUEL OU DANS DES 
SUPPLEMENTS PUBLIES PAR SONY. LES REGLAGES DE CIRCUIT 
DONT L’IMPORTANCE EST CRITIQUE POUR LA SECURITE DU 
FONCTIONNEMENT SONT IDENTIFIES DANS LE PRESENT MANUEL. 
SUIVRE CES PROCEDURES LORS DE CHAQUE REMPLACEMENT 
DE COMPOSANTS CRITIQUES, OU LORSQU’UN MAUVAIS 
FONTIONNEMENT SUSPECTE.