PHILIPS 28PT4255/00
Manual de Servicio

and overviews

6

Fault finding trees, diagrams and overviews
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Remark : In normal operation the Red LED lights in half intensity and in standby-mode the LED lights in full intensity

L9.1E

17

6

Fault finding trees, diagrams

Connect a pattern generator to the arial input. Set Patt.gen. to 475,25 MHz, colourbar, stereosound, PAL B/G (for France SECAM l). Put the Mainsswitch : on. In normal conditions the set will start with the Red LED blinking for one second in full intensity, one time then after a few seconds more in half intensity while the picture and sound will appear.

1111 Does the red LED blink for one second in full intensity, one time ?
Yes Yes No

Does the red LED light in full intensity continuously ?

No

Is the Power supply hicking ?

No

Any secondary voltage present ?

No

(A1); <P1> present?
Yes

No

Check/Replace (A1); SW0231,F1500,D6505 Note: If F1500 is defective, then also check R3503

Yes

1713

111D Do picture and sound appear properly ?
Yes No

A
Yes

Ensure communication with the RC, Check/Replace (A8);IC7680 Put the set into the Service Default Mode either via the DST or by pressing the buttons on the RC in the following order :062596<MENU>, or via the service pins An error code is indicated by the blinking LED via the SDM. n-times blinking means error n. See also chapter 5.5 for detailled information

The load of the power supply is too high. Isolate each branch of the load one by one, until the hicking disappear. Continue with the fault finding for the branch, which causes the overload. The branches are: (A1); AudioSupply +VBATT MainSupply Vaux

Check (A7); <C1>,<C4(reset)> 3V3, Check/Replace TS7603,TS7604 IC7600 X1660 (A8);LED6690

1111 (A1); <P2> startpuls present?
No

(A1);<P3> Voltage present?
Yes

No

Check/Replace (A1); D6540,C2540,D6510, R3510,R3529

Yes

111A Check/Replace (A1); IC7520 R3525

1111 Check/Replace (A1); TS7518,L5552
No

(A1); voltage on TR5545 pin9 present ?
Yes

111A Check/Replace (A1); L5540,D6540,C2540 Vaux,F1572,L5573,D6560 IC7581 Note 1: IRIS SYMPTOM CODE 111A

Set is OK Check / correct Options list via CSM see chapter 5.5 of this manual for details
No

1 Is there an error indication ?

11

A

Condition code

Main symptom code

Extended symptom code

Yes

B

Note 2: (A1) means Drawing A1 <P1> means Test point P1

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