KV-21FA310 (serv.man2) - Sony TV Service Manual (repair manual). Page 17

If the setting indicated in Step 2 of Hold-Down Operation Confi rmation 
cannot be met, readjustment should be performed by altering the 
resistance value of R530, R531 component marked with X. 

 

3mA DC range

+

-

+

-

A

+

-

FBT

TP85

T503
FBT

TP85

R531 R530

DC Power Supply

digital multimeter

ammeter

 

 

Always perform the following adjustments when replacing the following 
components, which are marked with Y on the schematic diagram on the 
AW Board:

  

AW BOARD
IC600, PH602

Adjustment (Y)

1.  Using a Variac, apply AC input voltage: 130 + 2.0/-0.0 VAC

2.  Input a monoscope signal.

3.  Set the PICTURE control and the BRIGHT control to  

 

minimum.

4.  Confi rm the voltage on AW Board between TP23 and ground is less 

than 136.5 VDC.

5.  If step 4 is not satisfi ed, replace R530 and R531 on AW Board and 

repeat the above steps.  

3-1.  X R530, R531 CONFIRMATION METHOD 

The following adjustments should always be performed when replacing 
the following components which are marked with Y on the schematic 
diagram:

C531, C532, D519, D520,
D521, IC501, IC600, PH602,
R529, R530, R531, R532,
R533, R550, T503 (FBT),
T504 (DFT)

HV HOLD-DOWN
R530, R531

Part Replaced (Y)

Adjustment (X)

1.  Using a Variac, apply AC input voltage: 120 +/- 2.0 VAC.

2.  Turn the POWER switch ON.

3.  Input a white signal and set the PICTURE and BRIGHT controls to 

maximum.

4.  Confi rm that the voltage of more than 23.0 VDC appears between 

TP85 and ground on the AW Board.

1.  Connect the current meter between Pin 11 of the FBT (T503) and the 

PWB land where Pin 11 would normally attach. (See Figure 1).

2.  Input a dot signal and set PICTURE and BRIGHTNESS to minimum: 

IABL = 2175 + 100/ -325 µA.

3.  Confi rm the voltage of AW Board TP91 is 134.6 ± 1.0 VDC.

4.  Connect the digital voltmeter and the DC power supply to TP85 and 

ground. (See Figure 1).

5.  Increase the DC power voltage gradually until the picture blanks out.

6.  Turn DC power source off immediately.

7.  Read the digital voltmeter indication: 

(standard = 27.24 + 0.0/ - 0.1 VDC).

8.  Input a white signal and set PICTURE and BRIGHTNESS to 

maximum: IABL = 2175 + 100/ -325 µA.

9.  Repeat steps 4 to 7.