Zotac GTX 780 3GB DDR - missing/broken component. Indentify?

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • dicky96
    Sun Seeker
    • Mar 2017
    • 1825
    • Spain

    #1

    Zotac GTX 780 3GB DDR - missing/broken component. Indentify?

    HI guys, does anyone have one of these Zotac GTX 780 3GB cards and can tell me what this missing resistor value is?

    It's the timing resistor Rt for the Vram VRM PWM controller so the value is important.

    It's going to be in the several hundred K ohm range and you should be able to measure it OK in circuit if you have one of these cards, as it reads completely open with the resistor missing.

    Alternatively a boardview or schematic would help

    I have the Gigabyte GTX 780 schematic (attached) which has the same PWM controller (RT8811A) and that has 384K in this place on the schematic but is a different circuit as it also has a 47K resistor and 0.1uF capacitor here which my board does not have

    The RT8811A datasheet typical application (attached) shows 500K Rt on pin 9 and does not have the 47K but has 1.0uF in this circuit

    If i put the wrong value I will have the PWM controller running at the wrong frequency (380K->500K is about 100KHz different) and I imagine that would be a *bad* thing to get wrong

    Cheers
    Rich
    Attached Files
    Last edited by dicky96; 01-14-2022, 11:18 AM. Reason: pics
    Follow me on YouTube
    ------------------
    Learn Electronics Repair
    https://www.youtube.com/channel/UCFX...R8UZ2vg/videos
  • dicky96
    Sun Seeker
    • Mar 2017
    • 1825
    • Spain

    #2
    Re: Zotac GTX 780 3GB DDR - missing/broken component. Indentify?

    Someone on my YT channel identified the value of the missing resistor, he had the same card and measured it for me. It's 383K, same as on the similar Gigabyte Schematic

    https://www.youtube.com/watch?v=z6BhFafIPro
    Follow me on YouTube
    ------------------
    Learn Electronics Repair
    https://www.youtube.com/channel/UCFX...R8UZ2vg/videos

    Comment

    • TimTech
      New Member
      • Aug 2022
      • 3
      • usa

      #3
      Hello OP. I know this post is old. I have a gtx 780 with C728 and the small cap below it missing is there anyway you can measure those for me?

      Comment

      • TimTech
        New Member
        • Aug 2022
        • 3
        • usa

        #4
        I was able to get a board view NVM

        Comment

        Related Topics

        Collapse

        • T4H
          RTX 2080 ti (Zotac - triple fan) - No video output / Vcore / Vmem missing
          by T4H
          Hi,
          I have an RTX 2080 ti (Zotac - triple fan) with no video output.
          So far I have measured the following:
          • PS_FBVDD_PH3_SW = 40 ohm to ground (Micron ICs) - Memory should be fine right?
          • 12V power rail present
          • 3.3V power rail present
          • 5V power rail present
          • 1.8V power rail present
          • Vcore power rail missing --> PS_NVVDD_VREF is present. (from uP9512P / U812)
          • Vmem power rail missing --> Not there because Vcore power rail is missing.

          Any idea? I have already tried to flash the BIOS chip (backup got created) - sadly no changes.
          Source: https://www.techp...
          08-19-2023, 08:14 AM
        • liquidzorch
          Missing resistor on BQ ILIM pin. DA0P5JMB6D0
          by liquidzorch
          Hello. I can't find the schematics anywhere for this motherboard, does anyone have one, and can give me the resistor value for the BQ728H missing in pic below? I already read the dadsheet, and this resistor value is calculated, so I can't just go with whats in the "typical" diagram.

          On a second note, could this resistor cause it to only boot with the battery and not the charger? It boots fine with a charged battery, but will not turn on with the charger (nor charge). The 19v does not get past the first mosfet, it recieves pulses to turn on, but something is preventing it....
          12-18-2023, 01:56 PM
        • pete61
          Gigabyte 4080 Super Gaming OC with a resistor and three caps missing
          by pete61
          Hi all I have got a gigabyte 4080 super gaming oc with a resistor and three caps missing, Can anybody please tell me what the values for these are, See pic for details, Thanks in advance....
          05-21-2025, 09:46 PM
        • Grucha98
          Zotac gtx 1060 3gb missing one rail
          by Grucha98
          Hello everyone, i have zotac gtx 1060 3gb, and it has missing one rail. I think its 1v but I'm not sure. This rail has 34 Ohms, but after test on on my testbench, it drops to 2ohm, after some time it back to 34 Ohms. Next to this coil is up1727q. And there are 3,3 on vin pin and 5v on vdd pin. I changed this chip with another one but it didnt help. When i tried Short circuit test, core didnt heat up so maybe its still alive. I dont have thermal camera :/. I dont have boardview and schemstic for this GPU too. What should i check next? Or maybe its just dead core?
          04-11-2024, 08:09 AM
        • jinu_j
          Dell 2209WA - power supply - Fusible Resistor replacement
          by jinu_j
          Hi

          I am trying to repair an ancient Dell 2209WA Monitor which suddenly shut off with a pop sound. On investigation found that one of the fusible resistors had blown. Further investigation identified multiple components as faulty because of which the fusible resistor blew. Please refer the attached circuit diagram showing the components that were found to be damaged.

          1. FR950 - blown fusible resistor - 0.2 Ohm 1W
          2. Q950 - shorted Q950 MOSFET - 650V 10A N Channel Mosfet
          3. R835 - Blown Resistor - 20KOhm SMD resistor
          4. D930 - Shorted Schottkey Diode...
          05-03-2025, 10:51 PM
        • Loading...
        • No more items.
        Working...