Reflow main board techniques

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • grimacelord
    Badcaps Veteran
    • Jan 2017
    • 380
    • USA

    #1

    Reflow main board techniques

    Hey guys. I have a TV that I am troubleshooting in another thread that leads me to believe reflowing the main processor may fix my problem. Problem is, I've never reflowed a TV main board before. I have successfully reflowed dozens and dozens of laptops, game consoles, etc. using a hot air rework station with bottom preheater. I am assuming the process is the same as I have developed a sort of standard technique over the years that is 90% successful on laptops and game consoles. I wanted to share my technique and see if it's suited for a TV main board.

    1. Remove main board and clean off any thermal paste, stickers, adhesive residue, etc.
    2. Place board on bottom preheater set to 150C for roughly 15 min or until a top temperature probe placed directly on the chips die reads 100C
    3. Apply generous high quality no clean flux such as amtech under the chip.
    4. Using a proper sized BGA nozzle for your chip, set the hot air roughly 1/4" above the IC and set to 150C. I use max air flow speed for my station, but others might need less.
    5. Apply 150C of hot air for 1 minute.
    6. Increase hot air temp to 200C after one minute and run for 30 seconds.
    7. Increase hot air temp to 225C after 30 seconds and continue for an additional 30 seconds.
    8. Ensure the top temp probe reads between 223-235C and remains in that range for roughly 10 seconds during the last 30 second flow time.
    9. Turn off hot air and preheater and allow to air cool until temp probe reads 60C or less.
    10. Clean off excess solder for appearance if that is important to you or just out of habit.
    11. Apply high quality thermal paste
    12. Apply a copper shim suited for your application on top of the chip that you just out thermal paste on then apply more paste on top of the copper shim and then install heatsink.
    13. Hope it worked.

    This works beautifully for me with computers and game console boards so, should I be ok with this technique on a TV main board?
  • trunks81
    Badcaps Veteran
    • May 2020
    • 265
    • Nederland

    #2
    Re: Reflow main board techniques

    Which station are you using ? This profile should work !

    Comment

    • diif
      Badcaps Legend
      • Feb 2014
      • 6978
      • England

      #3
      Re: Reflow main board techniques

      I have a rework machine, I use the same profile for reflowing everything, perhaps adjusting if the PCB is a bit thicker than usual.

      10. I think that should read remove excess flux not solder ? Which you should do as flux can be corrosive

      12. Why add a copper shim? the heatsink sticks straight onto the processors.

      Comment

      • grimacelord
        Badcaps Veteran
        • Jan 2017
        • 380
        • USA

        #4
        Re: Reflow main board techniques

        Originally posted by diif
        I have a rework machine, I use the same profile for reflowing everything, perhaps adjusting if the PCB is a bit thicker than usual.

        10. I think that should read remove excess flux not solder ? Which you should do as flux can be corrosive

        Yeah, I usually do clean up the excessive flux but there are some "no clean" flux types out there that claim it's non corrosive and ok to leave on. I usually don't anyway just out of habit of always cleaning it, but supposedly you can leave it if using one of these.

        12. Why add a copper shim? the heatsink sticks straight onto the processors.
        I've found, at least in the case of laptops (especially HP), that the heatsink alone isn't always sufficient to adequately cool the chip after it's already failed once and been reflowed.

        I started using copper shims originally on HP AMD GPU failures and stopped getting them returned after a few weeks or months. So now, I use them just about everywhere. You have to be careful that you don't add a shim too thick or you'll cause more problems.

        I buy packs of shims of varying thickness and use whichever is appropriate for the board I am working with. Has been working nicely for me so far, so I figure I'll keep doing it

        Comment

        Related Topics

        Collapse

        • Dani_2024
          Sceptre U550CV-UMR 4K LED, Bad Caps on Main Power Board?
          by Dani_2024
          Hi and thanks in advance for any input you might provide!
          I have a Sceptre U550CV-UMRD8POTV83BB 4K LED (this is a dumb tv) that I bought new in August 2021, so It's just completed 3 years.
          Main power board model: TP.MS3683.PC821 T-Con board: N4TP546UHDPU2L_BO

          Last Sunday I was watching a dvd and fell asleep for about half hour, when I awoke the tv screen was black and couldn't get the dvd menu to show, so I changed the input to antenna and had sound but no picture, turned it off. I then got online and found this great site! ....read many troubleshooting tips and this...
          10-28-2024, 05:06 PM
        • ygorsan
          LG 55NANO77SRA TV – Menu scrolling by itself even after removing button board (Main Board EBU66792103)
          by ygorsan
          Hi everyone,




          I’m looking for help with a persistent issue on an LG TV model 55NANO77SRA, which uses the main board EBU66792103 (also used in LG UQ80 and NANO75/NANO80 series).







          🧩 Problem Summary:
          • The TV keeps scrolling through the menu or selecting items by itself.
          • I removed the physical button board (the entire panel with power and volume buttons) and also disconnected the flat cable (CN202) from the main board.
          • The remote control is not in use (batteries removed), and the TV still shows the same behavior.
          • I
          ...
          07-28-2025, 08:34 AM
        • jb_Bak
          Sony xbr-65x900c main board issues?
          by jb_Bak
          Hey guys great forum glad to have found it. I bought a Sony XBR 65X900C cheaply because it didn't work. No signs of life at all not even a light/led. All I hear is a brief high voltage sound when I throw the power to it.

          Didn't see any obvious signs of damage so right away started checking voltages. This is what I see:
          Power Board Connector that goes to Main board
          CN6401
          Pin 01 NC
          Pin 02 NC
          Pin 03 "BL_ON": 0V
          Pin 04 "N/C"
          Pin 05 "STBY 3.3V": 3.5V
          Pin 06 "GND": N/C
          Pin 07 "AC_OFF"...
          09-27-2021, 04:52 PM
        • JDC
          (SOLVED) - ONN 100012588 No Power, Then Rebooting After Main Board Change
          by JDC
          ONN 100012588
          Issue: No Power, Then Rebooting After Main Board Change

          Short answer: replace main board and power board
          Technical answer: replace main board and Q306 & Q307 on power board.

          Long answer:

          TV wouldn't turn on. Power switch was fine which means the main board isn't processing the power on signal. Replaced main board. TV turns on now but randomly reboots. Bad main board? EEPROM? Tried to pull main board and got a shock touching the corner of the board. That's weird. C334 (450V 10uf) capacitor is still holding a high charge....
          07-15-2022, 07:39 AM
        • m1ch43lzm
          HP Pavilion 15-eh Board DAG7HAMB8F0 - CPU throttling to 0.4GHz (PROCHOT_EXT) and black screen
          by m1ch43lzm
          Hi, this is my personal laptop, which the original board (lets call it Board A) blew up PU8700 (TPS51486), making a hole on the board, i had left the laptop at my desk one day with the battery fully charged and didn't touch it for a week, but when i tried to turn it on it didn't
          Thought the battery was dead, so i plugged in the charger then tried to power on, the power LED blinked once, charged LED still orange, unplugged the charger, plugged in again and I noticed the "magic smoke" smell, so i unplugged the charger, removed the back cover and saw the blown IC (the "magic...
          05-12-2025, 08:37 PM
        • Loading...
        • No more items.
        Working...