LG Flatron L1750S - Stopped to work

Collapse
X
Collapse
 
  • Page of 2
  • Time
  • Show
Clear All
new posts
Previous 1 2 template Next
  • rf.pereira
    Member
    • May 2017
    • 16
    • Brazil
    #21
    Re: LG Flatron L1750S - Stopped to work

    Thanks piernov and Th3_uN1Qu3!

    Sorry but I'm sure about the pin number, so I'll upload a picture of Q502 with what I think are the pin's numbers.
    Based on my picture:
    Code:
    pins 1 and 3: 4.29V
pins 1 and 2: 5.01V
pins 3 and 2: 0.72V
pin 1 and GND: 5.01V
pin 3 and GND: 0.72V
    Originally posted by piernov
    0.74V between 3rd pin and ground then? Q502 could be bad. Try to remove Q502 and put a capacitor between base of Q503 (pin 1) and ground, 33uF/6.3V at least I would say, then check if the monitor turns on.
    Did you mean base of Q502 (pin 1)? And ground = pin 2?
    I have a 33uF/25V, is that ok?


    Originally posted by Th3_uN1Qu3
    Do you get a green light when you push the power button or do you get nothing?
    Nothing happens...
    Attached Files

      Comment

      • piernov
        Super Moderator
        • Jan 2016
        • 4435
        • France
        #22
        Re: LG Flatron L1750S - Stopped to work

        Originally posted by rf.pereira
        Did you mean base of Q502 (pin 1)? And ground = pin 2?
        Yes, with the positive side of the capacitor on pin 1 and the negative side on pin 2.

        Originally posted by rf.pereira
        I have a 33uF/25V, is that ok?
        Yep should be fine.
        OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

          Comment

          • rf.pereira
            Member
            • May 2017
            • 16
            • Brazil
            #23
            Re: LG Flatron L1750S - Stopped to work

            Nothing happened...
            5.03V passing through the capacitor and even pressing the power button nothing happened.

              Comment

              • piernov
                Super Moderator
                • Jan 2016
                • 4435
                • France
                #24
                Re: LG Flatron L1750S - Stopped to work

                So you removed Q502 and you still have 5V on U501's RST pin? You could try to disconnect R535, but I'm not sure the µC will start reliably.
                OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                  Comment

                  • rf.pereira
                    Member
                    • May 2017
                    • 16
                    • Brazil
                    #25
                    Re: LG Flatron L1750S - Stopped to work

                    Originally posted by piernov
                    So you removed Q502 and you still have 5V on U501's RST pin? You could try to disconnect R535, but I'm not sure the µC will start reliably.
                    No, on U501's RST pin (7) I have 0V and 5V on pin 8.
                    Maybe I made a mistake in the first time you asked me the U501's values... sorry about that.
                    I'll upload the U501's datasheet.
                    Attached Files

                      Comment

                      • piernov
                        Super Moderator
                        • Jan 2016
                        • 4435
                        • France
                        #26
                        Re: LG Flatron L1750S - Stopped to work

                        No idea then, maybe there is an issue with U501 (dead or corrupt firmware for example)…
                        OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                          Comment

                          Previous 1 2 template Next

                          Related Topics

                          Collapse
                          • tony359
                            Removing electrical noise introduced by fan
                            by tony359
                            Hi all,

                            I am working on a sound processor, it tends to overheat so I fitted a fan inside. The fan is connected to the +15V of the PSU via a DC-DC converter based on the LM2596 to reduce the voltage to around 10.5V.

                            Unfortunately the analogue circuitry is picking up the noise from the fan in two ways:
                            1. The fan is close to the analogue section, the motor itself gets into the outputs so I'll have to move it somewhere else
                            2. Even with the fan running outside of the case, there is still some noise which is clearly going back to the processor via power line....
                            2 Photos
                            11-28-2023, 05:18 AM
                          • MegaZAC
                            Onkyo TX-SR805 noise in one channel
                            by MegaZAC
                            Surprisingly enough, this receiver doesn't have the DSP chip issue. The HDMI board does not get hot, and sound over HDMI works fine.

                            Regardless of the input, the right channel has noise that is clearly noticeable even on average volume level. The only cases when there's no noise is when VCR input is selected (some tracks on the board are damaged, maybe that's why), or if HDMI input is selected but nothing plugged into it. In all other cases, even when no input is connected I still have the noise.

                            There's some logic behind it. As soon as I select an input I get only left...
                            04-23-2025, 10:09 PM
                          • courtcircuit
                            Philips HTS8000 home cinema noise problem
                            by courtcircuit
                            Hello

                            I have since a long time a Philips HTS8010S/01 which has been old but was doing the job.

                            Since a few days, it starts by making a weird "static" nois when switches on for a few seconds to a minute and then works like a charm.
                            Noise loudly outputs from the 3 channels, even if no signal is sent by the controler.DVD to the subwoofer/amp unit.

                            I was thinking of a soldering that was starting to be damaged and that was only doing the job after a few seconds of heating, most probbaly on the power board
                            Removed each of tyhe boards
                            ...
                            02-08-2025, 08:22 AM
                          • karatzdi
                            Denon AVR 1908, High pitch noise on Surround back Left channel after long overhaul
                            by karatzdi
                            Hello,

                            I know some might say... just buy another one. Sell it as parts..!

                            So had this AMP for quite some time. Recently I saw light smoke coming out of the AMP. Had my fire extinguisher close by. Just kidding. Turned immediately all devices off from mains.
                            Let things cool a bit, and opened up the amp device. I clearly saw on the main board which hosts the 5X amp (5.1), 3 10 ohms 1W resistors had their leads looking black, while the rest of the remaining 2 x 10 ohms were brownish as being installed from factory.

                            Spent some time downloading the Service...
                            06-11-2024, 08:38 AM
                          • flat-earther
                            HP F4180 stopped working please help troubleshoot
                            by flat-earther
                            I was doing a large print job with my HP Deskjet F4180, and after about 50 pages the printer stopped in the middle of a page and the black ink light started flashing.
                            So I went to refill the black ink cartridge with a syringe, but found out it still had a lot of ink.

                            I tried to print a page again but every time it would print only a bit of the page and immediately stop with the black ink light flashing again.
                            I tried two other black ink cartridges, and the problem still endured, so I knew this problem had to be with the printer itself.

                            I ran HP Print and Scan...
                            05-11-2025, 02:21 AM
                          • Loading...
                          • No more items.
                          Working...