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KxngCrooked8
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Last Activity: 04-09-2024, 07:27 PM
Joined: 03-19-2024
Location: Boston, MA
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  • So, I was able to get my hands on a small variable voltage power supply. I hooked up 3.3V to PWR_ON, DRV_ON, and PDIM pins and the LEDs are still flickering. Plus, I'm getting the 105-110V at the LEDs which, according to the service manual I have, says that happens when the TV is in STBY mode. I'm not sure if that has something to do with the flickering. Any other ideas as to why the flickering may occur but only when powering it with my power supply? It still works fine for 15-20 mins if I plug the cable back into the main board.

    If I can't solve the flickering, I'll probably...
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  • maneatingmonkey...
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  • I wish it were that easy. The reason that I am doing this project in the first place, is because the LCD screen is broken. So I can't see any of the menus to adjust things. I also tried to mess with the settings when the TV did work and I could never get it to stay on indefinitely. It would always timeout/go into standby after some amount of idle time.

    I would also like to carry out these mods so that I can eventually use a variable voltage power supply to adjust the brightness of the LEDs.
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  • Diah[USER="75051"]Diah[/USER]

    I'm not sure what you mean by "check the LED BL if one turn off". Sorry. Could you explain a little more?...
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  • Diah...
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  • [ATTACH=JSON]{"data-align":"none","data-size":"medium","data-attachmentid":3245542}[/ATTACH] ‚Äč
    Here is a table showing the expected voltages at each pin.

    I plugged the cable back into the logic board, powered up the unit, and took a voltage measurement at the MS (DRV_ON) pin. It was reading ~3.1V.

    As I'm looking at this again, I was jumping 3V to pins 1 and 11 (PWR_ON and MS (DRV_ON)). That means that I'm not pushing 3V to pin 12 (PDIM). Would a lack of PDIM signal cause flickering LEDs? Still open to any ...
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  • I was able to measure voltage across the batteries. They are outputting 3.1V. I also verified that the 3.1V is making it to both the PWR_ON and the PWIM pins on the power board. This is true both when A/C power is connected and when it is not. I am not sure of how to measure the current. My electrical skills/experience are somewhat limited. I've only ever measure current with a clamp and I don't have one of them. I could possibly borrow one from work but will need to check. Since power is ultimately tied to both voltage and current, I assume the correct voltage with not enough current could also...
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  • I came across a service manual for my TV model that explains how to test the LEDs by using a 3V power supply (in the form of 2 x AA batteries) and connecting that 3V to PWR_ON and to PDIM with the ground going to PIN3. When I do that, I am able to get the LEDs to come on, but they flicker. Based on some measurements that I took before I disconnected anything in the TV, the PDIM was ~2.2V when the LEDs were being turned on by the logic board. What I'm assuming is happening is that 3V is a bit high and the power board isn't able to output that amount of power continuously. I'm hoping that I...
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  • LG 49LJ550M-UB Looking to do some mods

    Hello,

    I have an old(er) LG 49LJ550M-UB that I'm looking to convert into a light source/audio player.

    The only issue I'm currently experiencing is that I can't get the LED's to stay on permanently. I still have the intact LCD panel and have fiddled with all of the settings trying to get the LEDs to stay on with no luck. In lieu of that working, I'm hoping to trick the power board into keeping the LED's on. I think that I've found the correct signal that I need to send, >3V to the PDIM pin on the P201 connector on the power board. But I'm not sure where to grab...
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  • Hello,

    I'm a mechanical engineer by schooling who works as an equipment engineer now. I'm currently working on a project that involves an old LG LCD TV and was hoping to find some help here.
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