Re: Philips 75pfl5704/F7 No sndby power
hi A couple of things to check early on is the main fuse located next to the mains input. check continuity of this. if its reading open then you probably have component failure on power board. Look for anything thats burnt or has a hole in.
If its ok then chack you have power coming into the tv.
if standby light is not on at all then nothing will work.
Just be careful poking around on a power board there are some high voltages on there. post pics of boards
Im sure someone with more experience than me can help...
KevM
Member
Last Activity: 03-12-2024, 03:25 AM
Joined: 02-02-2021
Location: suffolk
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Re: Philips Pus 436401/12 flashing backlights question
In answer to the last post on here yes i did give up or rather put it to bed for a while. But i will now tell what the outcome was or what i discovered was that my tv which was an auction site cheap buy and had been repaired before and fitted with a replacement power board which was not the correct one for my tv.
It should have been a philips 715G-7350 but was instead a 715G-6973 which is known to have the problem when backlights are changed.
The tv worked fine for around a year or more till the problem...Leave a comment:
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Re: Philips Pus 436401/12 flashing backlights question
quite agree that just about everything {tv wise} on the forum originates from china i will order and get back to you when they arrive and fitted .Leave a comment:
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Re: Philips Pus 436401/12 flashing backlights question
hi Been away for a couple of days so only just read the post .
Unfortunately tpv101D is only available from china and have had bad experience of fake items from china. Is there a better alternative to that chip with same/ better specifications available from UK supplier.Leave a comment:
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Re: Philips Pus 436401/12 flashing backlights question
thanks all leds are brand new and they test good with an led tester. Check continuity on the wiring and checked ok i will check the caps you mentioned and possibly swap them out as i have a scrap G7350 board with very similar set up which strangely enough does not have the 2 low ohm resistors just a jumper in place.Leave a comment:
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Re: Philips Pus 436401/12 flashing backlights question
Just a quick update i flipped the board over with the intention of testing volts on the Ics and decided to try the freeze test and see if any component warmed quicker than the other . After switch on i normally get 15 seconds before the LEDs flash on and off but it was around 2 minutes before the on/off sequence started and only the 2 tpv101s got warmer quicker than anything else. Vcc was 12v and dim was 3.3v constant. Ill do more testing tonight when i get home.Leave a comment:
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Re: Philips Pus 436401/12 flashing backlights question
great thanks for thatLeave a comment:
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Re: Philips Pus 436401/12 flashing backlights question
Yes i did remove one of the small SMD resistor on both ICs to slightly limit the current flow ,my thinking was the new leds may be rated different but did not make any difference so i haven't replaced it as yet .I am thinking along the lines as you, open circuit on the LED- which gives me the voltage fluctuation mentioned in post 1 the heat sinks do seem to get quite hot and i cannot find a data sheet for the TPV101AD chip. Ill test the diode mentioned and try to see if i can make sense of the IC readings.Leave a comment:
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Re: Philips Pus 436401/12 flashing backlights question
Here's a couple of photos full board and led driver section. I have been round with the soldering iron touching up a few joints but found nothing suspicious.
I did change u8106 with a one from another Philips board but made no difference....Leave a comment:
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Re: Philips Pus 436401/12 flashing backlights question
Yes i still have the old strips but they don't have a protection Zener diode on them .
I take it you mean something like in the photo i attached of some Samsung strips. I have only ever come across a Toshiba set that had a shorted diode on the strip
Manual states a boost voltage of 48v for this power supply but i have only ever got 44v
when i switch on and stays steady.
Could one of the TPV101D ICs be faulty and breaking down so only one is taking most of the current and going into shutdown ?...Leave a comment:
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Re: Philips Pus 436401/12 flashing backlights question
R J No problem
i have enclosed pic of rear of circuit board and connector.
please let me know if this is what you want to see.
I understand the part about 2 channels of supply to the connector....Leave a comment:
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Re: Philips Pus 436401/12 flashing backlights question
The manual for this set is found by chassis code and the chassis is QM 16.3 and covers a whole range of philips power boards and different power units and not the easiest of manuals to navigate.
the backlights for my set are part number GJ-2K16-430-D512-V4-1 and the only difference between original and the replacement is the new parts come in 2 pieces whereas the original are one long strip . Would this make a difference?Leave a comment:
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Re: Philips Pus 436401/12 flashing backlights question
Hi reply to Diah , in post 6 you said this is my last post on this forum so i did not make any response to that post . I have only just realized the wrong picture was uploaded in my reply to you.
as an update over the weekend i replaced the 2 resistors pictured in post 1 which gave a 1.1ohm ,resistance the backlights came on but less bright { as expected} but took longer to start the on off flickering. i have attached a picture of what i think you are requesting of the string connections if this is not the case then sorry....Leave a comment:
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Re: Philips Pus 436401/12 flashing backlights question
i have attached photos so you can see for yourself . i did not design the tv so cannot comment on why so many leds on each strip. i have replaced several led strips over the last year and never had any problem like this one....Leave a comment:
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Re: Philips Pus 436401/12 flashing backlights question
Hi i do not have the screen in place at this time i understand the lights will come on without the screen in place. The leds are brand new.
there are 5 led strips of 12 on each strip all supplied from the same connector it does not matter which 2 strips I disconnect leaving 3 connected the lights stay on. which proves to me the leds are not the problem.Leave a comment:
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Philips Pus 436401/12 flashing backlights question
hi had loads of help from this forum getting TVs back up and running but seem to be hitting a brick wall with this one.
Backlights failed before Xmas so ordered a new set and after replacing them and putting the set back together was delighted to see it work for 15 seconds only for the picture to flash on and off and a quick look round the back confirmed the backlights were flashing on and off
I have a steady 44v at +vled and a fluctuating 0v to 10v at -vled when the light start flashing, a steady Bl-on voltage and steady dim voltage.
If i disconnect 2 strings of leds... -
Re: New Members - please post your introductions here
Hi Kevin from suffolk. Retired from power transmission and have been lucky enough to save a few tvs from extinction with a lot of guidance from this forum in particular. just got a couple yesterday and i think one may be a tricky one from threads i have alresdy read. cheersLeave a comment:
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