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Equipment Repairs => CRT TV forum => Topic started by: dboy23 on January 09, 2009,04:34:38

Title: Need help Philips 21PT3952/71R (L9.1A)
Post by: dboy23 on January 09, 2009,04:34:38

Hello,
I need help in repairing Philips  21PT3952/71R (L9.1A).
When I turned ON the main power button, continuous clicking of relay and continuous blinking of RED led.
When I checked the 9V regulator, there is 12V input voltage and 9V output voltage when the relay is in the ON state. Unlike in 5V regulator, if the relay is in ON state, almost 0V in the input and output pin, if the relay is in OFF state, there is only ~1V on both input and output.
Pls help.

Title: Re: Need help Philips 21PT3952/71R (L9.1A)
Post by: jan48 on February 10, 2009,15:46:29

Check the applications and 130V and applications, SDA, SCL in 7601 (ST24W04-5, 6pin). Write about your applications. Fundamentals of the new eeprom.

Title: Re: Need help Philips 21PT3952/71R (L9.1A)
Post by: dboy23 on February 12, 2009,01:43:55

Thanks for your reply!

I dont know how to check the applications (EEPROM IC). Pls advise.

Here are some inputs / checked I've done:
-  the DC voltages (also 140V) in the secondary of the xformer (5545) were ok during standby and turning ON/OFF if not on standby (while LED is blinking).
-  it went on standby mode when I removed the horizontal transistor (7460). if i returned the transistor, it is still on standby until I turned ON (using remote control) and the LED will blink again.
- the DC voltages in the secondary of the flyback (5445) were only half (ex. the 5V is only 2.5, 33V is only 15V...etc)  when it is in ON state (LED blinking, ON/OFF). Is the flyback already defective?
- 140V is also present in the collector of the horizontal transistor (7460).
- I also tried to isolate if the problem is on the E/W ckt or horizontal ckt by following the instruction in the manual (removed one jumper (9465) and connect a jumper on 9461).

Pls advise what else should I need to check.

I attached the schematic/service manual I got from this site.

Title: Re: Need help Philips 21PT3952/71R (L9.1A)
Post by: jan48 on February 12, 2009,05:58:10

Tr.5445 oscilloscope, you can check (at the time of incorporation TV) then the system works, therefore, protection can be underestimated applications. Check whether aplik. pin2 and pin 4 7401 (TDA9302H) must be equal. It may not work layout diverge V dorze I do not know English using Google Translate