Sony gdm-f520 monitor Service Manual

— 15 —

GDM-F520

2-1. HV REGULATOR CIRCUIT CHECK

1. Turn the RV901 slowly, and adjust so that high voltage is in the

specified range.

[Specification]: 27.00 ± 0.05 kV

2. Check that the voltage of D912 cathode on the D board is 17.0V

or more.

2-2. HV PROTECTOR CIRCUIT CHECK

1. Using external DC Power Supply, apply the voltage shown below

between cathode of D912 and GND, and check that the RASTER

disappears.

[Specification]: 19.95 ± 0.00/-0.05V

2-3. BEAM CURRENT PROTECTOR CIRCUIT

CHECK

1. Connect constant current source to a section between T901 (FBT)

pin and GND, and check that the RASTER disappears when

the specified current flows to the

pin.

[Specification]: 2.12 ± 0.00/-0.051 mA

SECTION 2: SAFETY RELATED ADJUSTMENTS

When replacing parts shown in the table below, the following

operational checks must be performed as a safety precaution

against X-ray emissions from the unit.

Confirm one minute after turning on the power.

Part Replaced ( )

HV ADJ

RV901

Part Replaced ( )

D Board C925, IC901, R901, R902, R905,

R924, R925, R926, RV901,

T901 (FBT),

• Mounted D Board

HV Regulator

Circuit Check

D Board C920, C923, D911, D912, R903,

R917, R918, R919, R920, R923,

T901 (FBT)

• Mounted D Board

N Board IC1001, RB1001

• Mounted N Board

N Board IC1001, RB1001

• Mounted N Board

HV HOLD

DOWN

Circuit Check

D Board C930, D917, R921, R932, R933,

R935, T901 (FBT)

• Mounted D Board

Beam Current

Protector

Circuit Check