Oh wow, did not see this thread got a reply (only latest reply sent me an email notification). Guess I'll provide an update on this issue.
I somehow managed to get this board working a while ago. Not really sure what I did to fix it. After trying a bunch of stuff (like removing the 6-pin IC), I decided to try some voltage injection (used 1v at a very low current limit) into those pads reading 173/137 ohms (put one probe on ground). After doing this, the resistance went high and the OC message went away. Affected port was now dead though. Did some more testing and found if measuring...
ezenia
Senior Member
Last Activity: 12-26-2025, 10:33 PM
Joined: 06-12-2020
Location: Hounslow
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ASUS PRIME B450 PLUS (rev 1.02) USB Overcurrent issue
Hello,
So I bought a faulty ASUS PRIME B450 PLUS motherboard off eBay. They said it was water damaged and they cleaned it. The PC POSTs and displays a message that it's detected USB overcurrent and will shut off in 15 seconds. I verified this myself. So I did some checks at the ATX connector 1st to see if the resistance readings looked OK. I found the 3.3V rail measures just 179Ohms which seems way too low. It's been much higher on other AM4 boards I've worked on.
So I did some Googling to see what the potential culprits are. It varies from bad protection diodes, bad... -
Requesting ASUS Prime B450 PLUS Rev 1.02 boardview
Hi,
Just wondering if anyone has a boardview for the ASUS Prime B450 PLUS motherboard (rev 1.02). It has a USB over current issue I am trying to solve. Measuring the 3.3v rail on the 24-pin ATX connector sees 166ohms which seems way too low. So I'm trying to figure out if this has anything to do with it or if there's something else wrong. Tried to search for a boardview, but nothing comes up.... -
Tried lifting all the coils on one side to see if that led to any changes in resistance. The side towards the Mosfets now shows very high resistance (it's in the kilo ohms). The side towards the CPU still shows that very low 000.2 ohms value. Surely that means the CPU is gone?...Leave a comment:
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Oh right, it shows "000.2" on my meter for the CPU. GPU one shows "000.8".
I can't see what else could be wrong. I tried programming another BIOS file that was posted in the requests thread for this model just to see if anything different happened. Same exact symptoms. I don't think it's a BIOS issue which is a shame. Some others with this exact issue (black screen, max fan) fixed it with a BIOS flash so was hoping the same would happen here, but the low ohms on the CPU coils says otherwise.
Would it be worth trying to desolder the mosfets one by...Leave a comment:
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Took heatsink off and checked coils around CPU/GPU.
CPU coils:
GPU coils:
Seems like the issue might be a shorted CPU? I've read that CPUs can read very low ohms. However, 0.02 seems way too low and is the same as when my probes touch so it doesn't look right. GPU is also low, but it looks a lot better than 0.02. It's closer to 1 ohm and these coils do get voltage when power is applied. So the GPU looks OK. The CPU doesn't. The PCH looks OK because those rails are all up and there's no shorts around that area. Really don't want...Leave a comment:
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Yes that coil reads 1.05V. Got an OEM Dell charger, plugged it in and same exact symptoms. When plugging in the charger, I do see the white led dimly flicker. After like 4-5 seconds, white LED comes on along with max fan speed and no display. Stays like this indefinitely and doesn't restart. If I press power button (just press not hold), it turns off. Some seconds later, it turns itself on again with the same symptoms. It only seems to do this auto-on with the charger. If on battery only, I have to press the power button to get it to do anything.
Recorded coil voltage measurements...Leave a comment:
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I will be getting a charger soon, just wanted to probe around and see if this board is actually fixable.
I found some schematics posted and a boardview on this forum for this board. I've been looking at them and doing some more voltage measurements. Everything seems to look OK, but there are some measurements on PQH01 I am not too sure about. Schematics show it's for the VIN +1.05V rail.
I've marked some of the voltages I've been measuring. Does that look normal or could it explain why the board is not passing POST?
This is with the battery connected. I...Leave a comment:
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Decided to try connecting my bench power supply to the laptop since I don't have the charger. The laptop behaves slightly differently with this. I did not connect battery. As soon as I inject power to the laptop at the DC-IN connector, I see the current jump to around 0.500A without me even pressing the power button. Moments later, the board comes on by itself and current jumps up to 0.800a and stays there. Keyboard backlight comes on and stays on. A white LED still comes on briefly (for maybe 2-3s) and goes off. Laptop seems to stay in this state until I cut my power supply or press the power...Leave a comment:
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Bought a faulty laptop from eBay. Fault is when I press power button, the keyboard backlight comes on. About 5 seconds or so later, the fans come on at full speed along with the white LED. The white LED remains solid white for a bit and then goes off. Screen is black with no backlight (not even a flicker). Laptop does not reboot by itself (I've waited long enough). To turn off, I have to force power off by pressing/holding the power button. Did all the basics (such as removing non-essentials, testing new RAM and different RAM configs, resetting CMOS) but it still occurs. So I am wanting to test...Leave a comment:
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Found a schematic for this board that showed this IC was the BIOS. So I've now desoldered the chip and soldered it to the CH341A. It's read the chip fine and I've saved the original on my PC (file size is 16,384KB which seems to be the correct size).
Now I am stuck on getting another BIN file. I tried going to the Dell website but they only offer .EXE and .RCV files. Is there a way to change these BIOS files to a .bin so I can try programming it?...Leave a comment:
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Dell G3 3579 BIOS chip ID
Hello,
I bought a Dell G3 3579 eBay. The fault was not mentioned and it did not come with charger. Before trying to power off battery, I did some basic checks on the coils (in resistance mode) to see if there was any short. None were reading short. Decided to power the board to see if anything happened. The keyboard backlight came on. About 5 seconds later, the fans begin spinning at max speed. The white LED comes on at this time, stays solid for a bit and goes off. Fans continue to spin at max. Display is black (no backlight). If I hold down power button, board goes off. I did give... -
Replacing YT5202A fixed the problem. Bulb now works fine (will now see how long it stays working). So YT5202A must've been some LED driver that somehow failed....Leave a comment:
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LUMIMAN Smart Bulb IC ID?
Hi,
I have a LUMIMAN Smart Bulb that suddenly stopped lighting one day. The bulb is still detected in the app, but won't light. I've probed around and nothing seems to look off with any of the diodes, caps or resistors. The Bluetooth/Wi-Fi module seems to be working as it's still detected in the app. I even tried deleting and re-pairing the bulb (it didn't light, but I was still able to follow the pairing instructions), it re-paired fine, but still no light.
In diode mode, the LEDs all light up when probed so I'm guessing this means the LEDs themselves are OK. I was expecting... -
Alba CBB16 replacement switches
Hello,
I've been given an Alba CBB16 radio to look at. The issue was no sound from either speakers when switching to the radio. They'd just be some buzzing/static. I did some troubleshooting and found that if I mess with the switch in certain ways, the sound cuts in and out on the right channel speaker. It'll go from quiet with some static/buzzing to really loud and clear depending on how the switch is moved. This told me that the radio at least has an issue with this switch.
The switch appears to be broken on the inside causing a poor connection. I tried cleaning it... -
So I've been trying to figure out what is wrong with the board and so far this is what I've found (not sure if some of these are considered issues):
- DM804 and DZM805 appear to be bad - diode mode shows OL in both directions even when out of circuit.
- DZM806 may be bad as well - I get OL in one direction (red probe on lone pin) and then 2.2V on one of the pins and then OL on the other (black probe on the lone pin). I got these readings both in-circuit and out of circuit.
- QM802 is shorted on all 3 pins. Guessing this is what took out the diodes. QM801 doesn't appear to be shorted.
- TM802 may
Leave a comment:
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Re: Samsung LE32A456C2D TV no power
Is it normal for RM812 and RM814 (47Kohm resistors) to be measuring 10.9ohms in circuit? Just wondering if that's normal behaviour or if that signifies an issue somewhere. I tested both of them out of circuit and they read 47Kohm.
EDIT: looks like TM802 was the cause. I desoldered that and now RM812 and RM814 show 47Kohms in circuit.Last edited by ezenia; 11-18-2023, 08:51 PM.Leave a comment:
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Re: Samsung LE32A456C2D TV no power
So far I've removed the glue from most of the components. There's just one more that has glue touching the capacitor legs. I'll remove that one later on.
I decided to take out the QM802 component as I was getting continuity on all 3 pins while it was in circuit. When out of the circuit, the same thing happens. So it looks like QM802 is bad?
The two jumper wires next to the blown blue cap still have continuity across both pins. Does this mean they're still good and don't need replacing (just cleaning)?Leave a comment:
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Re: Samsung LE32A456C2D TV no power
More to do than I wanted/expected, but I'm going to try working on it when I can. It'll be good free practice even if I don't get it working.
For removing the glue, what is used? It seems too hard to just scrape off with something like a flathead screwdriver.
The fuse next to the power connector, marked T6.3AH 250V on the board, is blown.
I'm not too sure about the light bulb test. I probably won't attempt that as I don't know exactly where or how to safely connect the bulb to the circuit. I've briefly...Leave a comment:
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Re: Samsung LE32A456C2D TV no power
I've also attached a photo of the burn mark on the TV's chassis. Is this mark indicative of damage done to the TV itself, or is it there because of the blown components on the power supply board?...Leave a comment:
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