Speaker A
Today at our bench, we have a Gigabyte motherboard. [music] This board came to me with a no post issue. It would power on, but there was no display output and no LED lighting at all. It took me about 5 days to track down the culprit,
A detailed repair walkthrough of a Gigabyte B550 AORUS Elite EX motherboard with no post issue caused by damaged capacitors and VRM components.
Key Takeaways
- Damaged or missing VRM components can prevent CPU power and cause no post issues.
- Restoring PCB traces and pads is critical for repairing knocked off components.
- Proper diagnostic measurements help isolate power rail and component failures.
- UV solder mask protects delicate repairs and prevents future shorts.
- Even complex motherboard faults can be repaired with patience and detailed inspection.
Summary
- The Gigabyte B550 AORUS Elite EX motherboard powers on but shows no display or LED activity.
- Initial resistance measurements on power rails and components showed no shorts but missing Vcore voltage.
- Visual inspection revealed multiple knocked off capacitors, damaged traces, and a critical missing resistor in the VRM current sensing circuit.
- The repair involved removing damaged components, restoring PCB traces with thin trace pads, and resoldering capacitors and resistors.
- UV solder mask was applied to protect restored traces and prevent shorts.
- After repairs, the motherboard powered on successfully with proper current draw and LED indicators.
- The HDMI output showed a successful POST screen, confirming the board was revived.
- The repair highlighted the importance of VRM feedback and current sensing for CPU power delivery.
- The board had signs of previous repair attempts but was ultimately fixed by addressing missing components and trace damage.
- The video provides a thorough step-by-step diagnostic and repair process for complex motherboard faults.
Full Transcript — Download SRT & Markdown
Speaker A
and [music] the cause turned out to be very unusual. That's exactly what made this repair so interesting. [music] It really forced us to look at the repair process from a different perspective. We'll be restoring [music] multiple traces, soldering knocked off components, almost
Speaker A
replacing the VRM controller, and doing lots of soldering [music] work as usual. So, get into a comfortable position in front of your TV, grab a cup of something nice, and let's go.
Speaker A
Hello everyone. Today on our bench is the Gigabyte B550 AORUS Elite EX version 2. This is a solid gaming AM4 motherboard that came to me with a no post issue. According to the customer, it powers on the fan spins, but there
Speaker A
are no LED lights and no boot. Let's try to investigate the issue and see if we can bring this board back to life. As usual, we'll start by measuring the resistances on the main power rails.
Speaker A
So 2.3 volts we have 423 ohms, 5 volts it's kiloohms, 12 volts it's also kiloohms, 5 volts standby power 5B it's 134 kiloohms - 12 volts there's nothing here, um main coils I guess this is 1.8 volts.
Speaker A
So, kiloohms. Let's do memory. Memory coil 900 ohms. And this is a PCH power coil. Mega.
Speaker A
Okay. Way too much. Um, what else do we have here? We don't have any open. So, we can just check the Vcore.
Speaker A
It's 47 ohms without CPU. Then the CPU. Uh it's 91 mega ohms and CPU to Vcore just to be sure that 12 volts is not shorted to Vcore and we can put the CPU safely there. So it's 53 mega ohms,
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okay or 47 ohms for Vcore. Perfect. So basically we can try to power it on.
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[music] [music] For this test, I will use Ryzen 3200G AM4. CPU is in place. Now power on and 107 milliamps. This is healthy.
Speaker A
Pressing power button. And we have just partial power consumption. So there's no Vcore. I guess 500 milliamps is just basically a standby and 1.8 volts, I guess.
Speaker A
Let me check with the multimeter. What do we have? And we have 2 and 12 volts for the memory. Okay, there's nothing here.
Speaker A
Um, I guess we put it right here. 0.9 volt. This is a CPU. And uh what about leg number eight of the BIOS? 1.8 volts present for sure.
Speaker A
There is no Vcore within this consumption. There should be 5 volts. 5 volts.
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And that's it. Other voltages are covered by heat sinks. I guess we need to disassemble the board and make a visual inspection under the microscope.
Speaker A
Right. [music] [music] For these red marks here [music] like an exclamation point. This is clean. [music] There's no signs of blown MOSFETs.
Speaker A
What is that red dot [music] here? Does it mean that it's not working? Um, looks to me that this board [music] was already serviced somewhere because all of those red marks are very concerning.
Speaker A
[music] Uh let's look at the microscope. So first I would like to see [music] the VRM area.
Speaker A
And so there's nothing critical. [music] Okay. What [music] about the PCH? Do you see that red dot? I don't know.
Speaker A
What does it mean? This is kind of concerning because [music] uh during the manufacturer usually no one marks the PCH but it looks like this dot was applied before applying the thermal paste.
Speaker A
That's much better. Okay, right here we have an SIO chip. I don't see any damaged components near the SIO. The SIO looks good. Here is memory production, memory wattage, and CPU wattages.
Speaker A
Yeah, I don't [music] see anything critical. So, um, usually those markings are made by the manufacturer [music] and it means that uh this chip was pre-programmed during the manufacturer or after the manufacturer mounting [music] here. So, this is like a quality
Speaker A
mark that it has been uh programmed. Let's see the flash BIOS chip. And the BIOS chip looks nice. I don't think it was disordered. Looks promising. Okay. What's here? Here we have the network controller and the audio controller is over here.
Speaker A
CPU area. And I already see here that there is a knocked off capacitor. So um right here and this pad with this trace is basically also dismounted from here.
Speaker A
This is not critical. The motherboard can run without it. Oh, I see. So there's more damage uh on the back side of the board and those caps those are not filtering caps. You see that there is a uh signal pair
Speaker A
goes. So these caps are uh high frequency filters. All right. And so I see that here we don't have pads as well. So those pads they need a restoration. Let's go to the VRM area. And okay, of course.
Speaker A
So this cap is the filtering cap of the Vcore. This is Vcore. And this is critical because without this uh resistor we don't have a Vcore phase or we don't have a feedback from that phase. So that
Speaker A
means that this phase is not working and I'm not sure that VRM controller will assert power good signal without this resistor.
Speaker A
So okay there's no cap. Um, what else? Right here as well. There's no cap.
Speaker A
Those caps both are. Okay, this is knocked off here as well. Okay, that's the damage.
Speaker A
And this is smashed or blown. I'm not sure. Looks like it's smashed. Okay, this area is intact. There's no damage.
Speaker A
at least something. Uh what about under PCH? So this is area under the PCH and okay we have a mass over here as well. So there's a lot of components those caps right yeah this is a capacitor
Speaker A
I don't know what this element is could be a cap but could be an inductance or resistor.
Speaker A
There's caps. So highly bad that they short the paths between them. So uh [sighs] we have a lot of components absent here and damaged and this uh knocked off resistor from one of the VRM MOSFETs.
Speaker A
This is a critical part and so I guess that we have to try to solder them on to repair it uh and try to see if it helps because I guess because of that resistor we cannot get a power good from the
Speaker A
multicontroller and our multicontroller it does not uh provide PWM signal and those Vcore MOSFETs never start. So there's no CPU power. So let's do it.
Speaker A
The first thing we need to do is clean the pads and remove the remaining parts of the knocked off components so we can install the new ones.
Speaker A
[music] [music] Hey, [music] hey hey. Heat. Heat. Hey. [music] Now we move on to restoring the knocked off paths. We need to expose the [music] traces and solder new paths to them.
Speaker A
I'm using trace pads with a thickness of 30 micrometers, which is basically [music] about two times thinner than a human hair.
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Heat. Heat. Heat. Heat. I apply UV solder mask to keep the traces and pads in place. It also protects them from damage and prevents short circuits.
Speaker A
Hey, hey hey. Heat. [music] Hey. Hey. Heat. Heat. [music] Okay, let's see if all that work pays off.
Speaker A
[music] Okay, let's power it on. Pressing the power button. And yes, it's working now.
Speaker A
It's 2.26, 2.6 amps. Wow. And LEDs light up. Okay, let me connect the HDMI capture card to see if we have any changes.
Speaker A
Okay, HDMI connected. Now I need to show you the post screen. Okay, let's try again.
Speaker A
Yeah, it's powering on. It's almost booting. Okay, 2.6 See 2.3. Well, we have a post screen 4 amps.
Speaker A
Okay. And we do finally. So, the board is alive. I'm so glad to see this. So much work has been done.
Speaker A
So, um what has been done to this board? There were a lot of knocked off components on the back side of the board. So I had to remove all damaged capacitors from the back of the board.
Speaker A
Restore traces of differential pairs used in PCI Express signal lines over here. Soldered knocked off resistor used in VRM current sensing circuit.
Speaker A
This is uh line number four right here right where the exclamation mark was. So do you remember that exclamation point?
Speaker A
It was painted right on the MOSFET number four as I remember which has this knocked off resistor. I guess someone has already tried to fix this board and found no connection on current sensing pin of this MOSFET but couldn't figure
Speaker A
out how this happened. Uh okay, what else has been done? It was soldered most of the Vcore filtering uh as well as caps in the...
Speaker A
Um I measured the voltages on the VRM controller and um this controller has one enabled signal and two power good signals. The enable signal is called CPU VDD enable.
Speaker A
It's one of the steps in the motherboard startup sequence. This signal tells the controller to start the Vcore and SOC power rails which are the main CPU power lines. In this case, both power good signals were low. So I initially
Speaker A
suspected that one of the SOC MOSFETs might be failing. There's two SOC MOSFETs, number one and number two. In this case, both power good signals were low. So I initially suspected that one of the SOC MOSFETs might be failing,
Speaker A
specifically the two MOSFETs on the right side. However, after measuring voltages and resistances across all the MOSFETs, I couldn't find anything unusual. Everything looked perfectly fine with no signs of damage. Then I remembered that one cap was missing and
Speaker A
I found that it should be located right under the VRM controller, the VRM controller and the cap that side. So this cap is a regular bypass capacitor used to filter the internal voltage regulator inside the controller. After soldering this cap back in place, the
Speaker A
board finally booted without any issues. I think it's also worth noting that manufacturers don't provide data sheets for components like this. They are most likely made exclusively for motherboard manufacturers, which in practice makes the repair process much more difficult.
Speaker A
This is a great example of how a single missing cap can completely stop a motherboard from working. It was the first time I encountered a problem like this. This board definitely deserves a [music] proper cleaning and reassembly, and I hope it will serve just as long,
Speaker A
if no longer, than it already has. I guess that's it for this one. I hope I didn't bore you with the long soldering and restoration process. I tried to keep it as compact as possible. I want to thank you for all the kind words in the
Speaker A
comments. They truly inspired me to keep recording more videos. I try to answer all of your questions in the comments as always. Also, please don't forget to like and subscribe. See you in the next video.
Topics:Gigabyte B550 AORUS Elite EXmotherboard repairno post issueVRM repaircapacitor replacementPCB trace restorationmultimeter diagnosticsRyzen 3200GsolderingFix the Pixel
