Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
PS is working finally after replacing LED driver IC OZ9906GN.
anupkg1985
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Last Activity: 11-03-2024, 08:55 AM
Joined: 09-25-2020
Location: SF Bay Area
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
R21 is reading as 1.2ohms and removing c2 doesn't change anything. Voltage drops back to 1.7V if resistor R407 is connected back. Is it worth replacing U2?Last edited by anupkg1985; 01-28-2023, 09:26 PM.Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
Yes, removing R407 makes it back to 13v, so the U2 is bad?Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
On R457 its 13v then gets droped on each resistor and ultimately on R407 it is 1.7volts.Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
It ultimately connects to U2 vcc pin 9, where I'm getting 1.3volts.Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
I have already changed R457 as it was bad (comment#27) same for R41. Both of them were reading high than there ratings.Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
I changed to new strip however no backlight. Not sure whats wrong with driver circuit. Anybody any pointers?Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
Pretty much aligned with you guys, I tested led strips with LED tester and found that the strips are drawing 0.28A current where the board output is 0.35A, so I would try replacing the entire strips and will update again. Meanwhile I found another bad resistor on secondary side R457 (47 ohms) but it was reading around 3.6K ohms. It's on the VCC line of the U2, however replacing it doesn't change anything so will give a shot by replacing strips. Thanks @R_J and @Davi.p for your support.Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
UPDATE - I just found that resistor R41 rated for 10ohm was actually reading 13K, after replacing that one PSU is stable now. No more clicking noise so PFC is working fine. However there is still no voltage on LED terminals. Backlights doesn’t light up. I tried to get initial reading while plugging tv into power however no voltage at all. It always remains 0V when measured across + and - terminals of LED connector. However when I measure GND (chasis) to + LED, it measures around 100V and GND to -ve LED it is around 60V. Not sure...Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
If I connect-ve of LED strings to chasis or ground, led lights up however it goes on and off with same rhythm of clicking sound. Not sure if connecting negative terminal of LEDs to ground is good idea. But looks likes something is bringing down the PSU and that's the noise of clicking.Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
My bad, it's connected to collector of Q407. Cap 429, negative is connected to Emmiter and positive is connected to Collector pins....Last edited by anupkg1985; 01-25-2023, 07:00 PM.Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
It's connected to Emmiter of Q407, shouldn't it have any voltage present on it?Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
Please find the marked cap in attached snap, I'm not getting any voltage on it. It's 50V 47mfd cap.
U2 number - OZ9906GN, probably this is the datasheet - [url]https://www.promelec.ru/product/318597/[/url]Re: LG 50UH5530 - Power supply - 168.../318597/[/url]...Last edited by anupkg1985; 01-25-2023, 06:08 PM.Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
Ok, but I'm curious why there is no voltage on c15 as mentioned in comment#8? Is there any to force start the led driver or taking out from protection mode?Leave a comment:
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Hi Budm, could you take a look at my post
[url]https://www.badcaps.net/forum/showthread.php?t=114778[/url]https://Hi Budm, could you take a lo...t=114778[/url] -
Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
I'm getting around 100v on +terminal of the led connector however voltage is stable on -ve terminal. Its jumping fro. 0 to 60v when measure against the chasis. What could be wrong with led driver?Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
F3 is ok and voltage on it is around 97V. Also there was issue with 3 leds which I replaced with new led, not the entire strip. However it doesn't power on as well as leds strips are off. I tested strips with LED tester and looks good.Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
When all boards connected, tv doesn't power on. Power indicator just blinks and everything resets.Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
Yes there is voltage on secondary 12.5v which is bit fluctuating as well as there voltgaes present on caps on secondary side except C15 which is 50v cap. Also there is very fast fluctuating voltage on Q3 gate however on Q2 and Q1 its steady 395v and 165v respectively.
Could not find any bad/ shorted diode on secondary.Leave a comment:
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
I just tested the board by removing ZD12, there is around 395v on main caps however there is ticking sound from transformer I believe. Also the voltage on main cap is fluctuating from 395 to 400volts. Voltage on c14 reads between 11 to 16 volts.Leave a comment:
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