LG 50PV450-UA no power

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • cmslick3
    New Member
    • Apr 2019
    • 2
    • United States
    #1

    LG 50PV450-UA no power

    Hello all,
    I'm troubleshooting an LG 50PV450-UA for a coworker of mine, I'm stumped and looking for help.

    Original issue: TV shut off, no standby light on front panel, no clicking when plugged in.
    To date troubleshooting:
    No bulging caps, no obvious heat issues, no destroyed components.

    Checked main fuse, GOOD. Checked fuse F302, BLOWN. Replaced fuse F302.
    Plugged in TV fuse immediately blows.

    Tested D304(SR 104) and R305(0.33 ohm) both blown, Replaced. Diode had to be NTE585 which was the only locally available component. Replaced F302 again.
    Plugged in TV fuse blows immediately.

    Tested Voltage regulator IC301 and it's completely shorted. Replaced with STR W6053S IC, checked diode and resistor, replaced F302 AGAIN...
    Plugged in TV and nothing happens, fuse did not blow, but still no standby light or voltage.

    Checked voltage at F302 and it's only reading 100Vdc, should be 160Vdc at standby.

    Checked VA and VS, 5V and 17V jumpers and all reading 0.

    Checked multiple diodes and resistors across the board, always desoldered, and nothing else seems blown.

    At this point I'm leaning towards ordering a new SMPS, but wanted to know where else to check.

    Thanks for your help.
    Tags: None
    • Unspun01
      Badcaps Veteran
      • Jun 2011
      • 339
      • Canada
      #2
      Re: LG 50PV450-UA no power

      I assume you checked all heatsink-mounted components? transistors, diodes, IGBTs, etc?

      IC301 likely failed and took out R305 and D304.

      I see 3 fuses F801, F101, F302. Are all 3 good?

      Check the 3 low resistance white 5W ceramic resistors in case they opened up.

      Check the low resistance 2.2ohm resistor? (red red gold gold ?) located near the heatsink by the two large capacitors and fuse F801. I can't make out these markings from a photo I found so I don't know if the resistor or fuse label are accurate.

      Can you identify the markings of the multi-pin ICs on bottom of board? I seem to recall one may be a L6599 resonant controller IC (PWM PFC) and it may be damaged also.

      https://cdn.badcaps-static.com/pdfs/...7b0cc85afc.pdf

      Check for VCC at pin 12, and try to verify other functions against datasheet. Or test for shorts between each pin to ground at the very least.

        Comment

        Previous template Next

        Related Topics

        Collapse
        • nicktasios
          Macintosh Quadra 840AV PSU
          by nicktasios
          I had my Quadra 840AV (which I recapped and had working) plugged in for some time without using it and randomly decided to turn it on today. Unfortunately it did not turn on. After checking the PSU, I found out I was not getting anything from 12V, only from the 5V rail. After a few minutes, I removed the PSU and plugged it back in the electrical outlet and it suddenly started making a weird sound and soon after smoke started coming out. I quickly unplugged it. I opened it up but on first instance I didn't see anything out of the ordinary really. I later turned it back on and one of the MOVs blew...
          1 Photo
          12-22-2024, 05:07 AM
        • Larrob19
          Samsung TV UN75NU7100/Power Board BN44-00874C
          by Larrob19
          Hello,

          I have a Samsung power board BN 44–00 874C that is dead. I have looked for a schematic but no such luck. I opened it up and found two Mosfets burnt QP801CS and QP802CS, also the main fuse. I replaced them and checked the two blue capacitors in front of them. They both tested good. I checked the Diode on the same heat sink and the two capacitors in front and they checked out OK. I plugged it in again and that blew the fuse and the Mosfets the second time. I plugging it in again hooked to a 100 W watt light bulb. The light bulb starting started flashing off and on. I checked...
          2 Photos
          05-08-2025, 12:49 PM
        • Babbar
          Argon SA1 audio amplifier power-supply - fuse blown after fixing the short?
          by Babbar
          I found a project in the electronics trash yesterday. A nice Argon SA1 audio amp with some electrical issue. Took it apart and saw that the 4A250V fuse was blown so started lifting components to find the short. Eventually got to two MOSFETs (model FTA14N50C) that are shorted and when i took them out the short was gone.

          Now i didn't have any replacements of the same model of course but i found a couple with pretty similar spec i thought (K10A60D & K12A50D) and put them in. Also replaced the blown fuse with a 3.5A250V one. Checked another time for short circuit and plugged it in....
          04-12-2024, 01:12 AM
        • Loretto
          Samsung SMPS BN44-00339A
          by Loretto
          Hi all,
          this unit comes from a samsumg LCD TV LE32C530F1W which stopped working after making a strong noise like something was exploded inside of it.
          I opened it and found that fuse FP801S was blown, capacitor CP814 was completely disintegrated and MOSFET QP801S was shorted.
          I replaced all of them and instead of the fuse I connected a 100 Watt bulb. Then, without connecting it to other TV boards, I switched it on, but the bulb begun to blink.
          I thought that maybe the bulb was somehow interfering with the normal operation of the power supply, so I replaced it with a fuse,...
          03-29-2025, 08:30 AM
        • Loretto
          Samsung SMPS BN44-00339A
          by Loretto
          Hi all,
          this unit comes from a samsumg LCD TV LE32C530F1W which stopped working after making a strong noise like something was exploded inside of it.
          I opened it and found that fuse FP801S was blown, capacitor CP814 was completely disintegrated and MOSFET QP801S was shorted.
          I replaced all of them and instead of the fuse I connected a 100 Watt bulb. Then, without connecting it to other TV boards, I switched it on, but the bulb begun to blink.
          I thought that maybe the bulb was somehow interfering with the normal operation of the power supply, so I replaced it with a fuse,...
          03-28-2025, 10:28 AM
        • Loading...
        • No more items.
        Working...