Author Topic: Philips TV (Fixed)  (Read 1367 times)

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Offline DarkZero

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Philips TV (Fixed)
« on: December 30, 2016, 09:39:34 pm »
friend left me 25" philips tv but its broken i approached repairing it since it has some nice features its small but with good specs

now i opened it and saw that supply was fried but i found schematic for it

i changed all parts that were dead but im getting some oscillations on the low voltage side checked diodes but really don't know how to check feedback circuit
i just feel so stupid not knowing to fix this with this low parts count ... the only thing i didnt use as in schematic is high voltage mosfet i used p10nk80zfp
i have to mention that someone gave it a try before me since 400v 100uF cap was missing but the chip was blown some resistors near mosfet so i figured mosfet died as well
i attached schematic
« Last Edit: January 02, 2017, 12:11:22 pm by DarkZero »
 

Offline GasGas

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Re: Philips TV
« Reply #1 on: December 31, 2016, 10:28:00 am »
Please tell your TV model to try to locate the service manual. This is a very basic source, it should not be difficult to repair. Have you downloaded the PWM IC data sheet from the primary side of the source? If the mosfet was faulty, it is 90% chance of the CI PWM having the same destination ...
 

Offline DarkZero

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Re: Philips TV
« Reply #2 on: December 31, 2016, 12:22:35 pm »
i changed pwm chip, mosfet and lots of small resistors aroun the mosfet i used all parts like in schematic i only used different mosfet which is basicly the one that works with 800v instead of 700v ill need to check what model is it,  schematic is in the attachment, i measured the output voltage 5vsb jumps between 3-7v and 24v jumps from 13-26v and on the scope its just a mess some weird looking sine wave on top of changing dc voltage
 

Offline GasGas

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Re: Philips TV
« Reply #3 on: December 31, 2016, 12:49:59 pm »
I found the schematic. If the voltages are pulsing at the output, check the IC 902, 903 and ZD903
 
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Offline edy

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Re: Philips TV
« Reply #4 on: January 01, 2017, 06:01:30 am »
This looks similar to my TV that I repaired a while back. Not sure if it will help, but here is my repair video with schematic and explanation of all the most common parts that fail as per the kit I got. It may help point you to another component that needs replacement. Good luck!

YouTube: www.devhackmod.com
"Ye cannae change the laws of physics, captain" - Scotty
 
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Offline DarkZero

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Re: Philips TV
« Reply #5 on: January 02, 2017, 12:10:29 pm »
Quote
I found the schematic. If the voltages are pulsing at the output, check the IC 902, 903 and ZD903

thx for suggestion

since these components were so cheap i didn't bother to test them so i changed them and indeed it worked, but i wonder why when so many components failed both in high voltage side and low voltage side why it didn't blow the fuse, PWM chip was missing top part and you could see inside mosfet im just glad that with all parts it costed like 7 euros to repair this so  :-+

thx again i fixed many things around the house using this forum !
 

Offline SeanB

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Re: Philips TV (Fixed)
« Reply #6 on: January 02, 2017, 09:27:52 pm »
Semiconductors blow a lot faster than a fuse. they often sacrifice themselves to save the fuse.
 


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