Diode decoding

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • 73buick
    Member
    • Mar 2011
    • 41
    • USA
    #1

    Diode decoding

    Attempting to fix a Samsung TV power supply. I believe I found a bad diode, only measuring .223 on my meter. The diode is a small barrel, about 4-5mm long and 3-4mm diameter. Its colored green/black (cathode/anode) and has 4H marked on the black side, read top to bottom, i.e. the H is below the 4.

    So anyone here know what diode this is and am I correct that its reading as bad?

    Or is this a schottky diode and is reading as it should?
    Thanks
    Last edited by 73buick; 08-15-2014, 07:30 PM.
    Tags: None
    • Agent24
      I see dead caps
      • Oct 2007
      • 4940
      • New Zealand
      #2
      Re: Diode decoding

      Assuming it is not shorted and measures only in one direction, it should be OK. The low forward voltage could well be due to it being a schottky. If you have the schematic you could confirm that.

      To find if it were leaky or such you would have to test it with a curve tracer.
      "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
      -David VanHorn

        Comment

        Previous template Next

        Related Topics

        Collapse
        • SuperAman
          PS5 HDMI port diode reading?
          by SuperAman
          I did an hdmi port repair for a PS5 and I lost the small diode z71 SOD923 on the back of the port. I did a trace repair for pin 19 of the port as well. Without the diode I get no display at all. I tried replacing the diode twice but after I get flux on it the marking comes off so I can't tell if I have it on the right orientation. When I measure I get a reading of 1(open) and 923 in diode mode. Is 923 a normal reading for these and also which side should the reading be with regards to the arrow on the board?...
          02-03-2024, 10:16 PM
        • abajor
          A2141 PP3v3_G3H_RTC_X Diode Reading .104V Voltage 3.39V
          by abajor
          Have an A2141 which is reading about 5.2V 0.07A on all USB jacks, started doing the measurements.

          PPBUS_3GH diode: measures good .45V
          PPBUS_3GH Voltage: maybe not so good 12.25V maybe bad T2? Unit did not come up in DFU on configurator.

          The weird so far is
          PP3v3_G3H_RTC_X diode: .104V (WTF?)
          PP3v3_G3H_RTC_X voltage: 3.39V (Normal)

          Stopped there attempted reverse voltage injection at PP3v3_G3H_RTC_X with 1V. Instead of the circuit sinking any current, My PSU suddenly reads 3.4V with no current draw.
          Not sure what any of this means...
          03-18-2025, 10:27 PM
        • iyas132
          Corsair RM 750 blown schottky diode near ES1DF
          by iyas132
          Hi there, i am currently diagnosing my corsair rm750 that wont turn on, after a power trip.

          Before the power trip, previously i need to push power button on my pc case quite a bit in order to turn the pc (and power supply on), however after the power trip now i cannot turn the pc on at all and i opened the power supply, and found out some of the component(s) are blown. (picture attached)

          My current diagnostic is that the (schottky) diode marked "SF" in the 5Vsb circuit are blown and possibly the ES1DF diode too.

          Can anyone help me identify the component...
          1 Photo
          12-30-2024, 01:34 AM
        • iMuhtaseb
          A2681 Keyboard, trackpad and sleep?!
          by iMuhtaseb
          Wow it's been a while since I posted!

          This is a weird case, it has a history of liquid spill a year ago but customer did not want to replace neither trackpad or keyboard.. fast forward for today:

          A2681 turns on but not trackpad or keyboard feedback (or external keyboard and mouse) and then after a minute or so the Mac sleeps..

          It's a NOT a sleep sensor or trackpad or keyboard or daughterboard or anything else (I replaced all those); it's the logic board..

          Tested another locked logic board on customer's top case and it posted with keyboard and...
          05-22-2025, 09:59 AM
        • karoliens
          820-01700 PPVCC_S0_CPU normal resistance to ground/diode reading?
          by karoliens
          I am working on this board that has some water damage though not around this rail but I measured it anyway to rule out that CPU is not fried.
          Resistance to ground on PPVCC_S0_CPU rail is 2Ohm and in diode mode it shows 0V.
          What is the normal reading on that rail?
          TIA
          09-11-2022, 12:55 PM
        • Loading...
        • No more items.
        Working...