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Last edited by anupkg1985; 01-25-2023, 07:00 PM. -
Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
The emitter of Q407 is connected to ground, C429 positive is connected to D407 and to Q407 through a 10Ω resistor. I can't follow where D407 goes.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.Comment
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
The only hypothesies i can make, zd12 act as voltage regulator for U1 and must be repopulated, u1 shuts down for ovp, check also its datasheet. But i checked DS and on supic pin there is already internal regulator, so two primary side small el. caps are suspected check them for capacity/esr.Last edited by Davi.p; 01-26-2023, 04:27 AM.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 whats wrong and why LED strings are not lighting up.Comment
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
Bad led stripsComment
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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.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?Comment
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
OMG!.. R41 & R457 how are marked?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.Comment
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
Where does R457 connect?Last edited by R_J; 01-28-2023, 08:04 PM.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.Comment
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
I would thing that is a bit low for a vcc, likey bore like 12v. Check the voltage on R407 (both sides) and R21
A closser look and I think R457 connects to +13.2VLast edited by R_J; 01-28-2023, 08:05 PM.Comment
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
You can't answer my question?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.Comment
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
so R407 has the same voltage on both sides so I can only assume U2 is defective. or If you remove R407, does the voltage on R21 come up to 12v?Last edited by R_J; 01-28-2023, 08:15 PM.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?Comment
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Re: LG 50UH5530 - Power supply - 168P-L5L01F-W0
C6 is the only other component on that line but I doubt it is bad, so most likely U2 is bad.
Just for the heck of it, is R21 ok and not high in value?Last edited by R_J; 01-28-2023, 08:31 PM.Comment
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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.Comment
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Vizio e601i-A3 - Has Sound and Display, But No Backlight - Bad Power Supply Board or Bad LED Bulbs ?I was given this TV from my great uncle. He said it just wouldn't turn on one day out of nowhere, replaced the TV, and gave it to me to possibly fix and use for myself.
Upon bringing it home and plugging it up, it showed a standby light.
I powered it on and without a flashlight, the display showed the "V" but the lighting is very dim, but visible.
The screen seems to blackout and stay black, but with a flashlight I can see the display.
With my Playstation 4 connected via HDMI, and running a game I can hear sound.
Assuming... -
I have wanting to do this project for quite sometime now and I finally found a switching power supply that will work on this desoldering gun station ZD-915 that the original switching power supply took a shit and just was not worth trying to fix it because this switching power is not quite big enough to handle the heater element and the vacuum pump
One note when I tested the switching power supply and the voltage control board I noticed that this desoldering gun heat up much faster than the original switching power supply which I was really surprised by to the point that I might buy... -
I have been working on this concept for quite some time now with limited success but recently I found a switching power supply that is setup for the voltage that this soldering station needs to operate at however it also needs part of the secondary circuit from the original switching power because you need several voltage rails
I once tried to get a ZD-915 desoldering station to work on a 18 volt battery power supply but unfortunately things did not go well but I did find a work around but I might try this idea again but going at a little differently more about this another time... -
The sub developed a constant popping every couple seconds from woofer and power LED flickering with nothing but wall AC connected. Connecting an audio cable didn't change anything. It doesn't play but a second or two of audio in between the pops.
Opened it up and discovered the power supply is making a faint clicking or ticking sound.
I measured the amp's output to the woofer and it pulses up to 50mv DC to be driver. The pulses coincide with the power supply ticking/clicking.
I measured the power supply output going to the amp board and it too has this pulsing. Voltage cycles... -
I have a 15 - inch Retina MacBook Pro from the mid - 2014 model. Here is the link: https://www.badcaps.net/forum/showth...light=820-3662 . The battery broke some time ago. After I removed the battery and plugged in the original power adapter, the MBP could boot up normally. However, when I checked with IntelPowerGadget, I found that the CPU speed was limited to 0.8 GHz, and it ran very slowly. Later, I found a solution on GitHub. There is an open - source project called cputune that can set the CPU running speed. So I can now run the MBP at full speed. But another problem...
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