I have an MSI motherboard here that seems to be missing a single small SMD resistor (as seen in photos)
Is there anyway of telling what the value of this is? (or perhaps just place a jumper across it)
I think someone purchased this and knocked this part off then attempted to glue it back on (hence the glue blob on the board there)
Here is the best photo I can find of the original part/area:
Here is the missing part (I’ve looked up close at this spot with a watch repair lens and I can see where the resistor was seated as there is a square mark in the solder - it also appears that the one side was soldered well but the other side was not - hence why it came off easy)
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Look it up on an appropriate schematic
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Measure the value of the corresponding device on a board of the same make/model
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Reverse-engineer the circuit to determine what an appropriate value is likely to be.
Give that idea some serious thought for a minute or two…
- If the component is missing, how do you know if it was a resistor at all?
- What might go wrong if a person randomly went around replacing components meant to do a job with short circuits?
First off thanks for a reply!!
How do I know this was a resistor? Well if you had read my post fully you would see that I also posted a photo of the stock/original motherboard - you can see it clearly - it’s black - while the capacitors of this size are brown.
2nd to order a replacement board is another $350+ then I have to wait for it then test the resistor and then return the MB… I mean that’s fine and all but that means I have to have fork out another $350+ until I am able to return the board.
I understand the “short” issue, however this is most likely a resistor on the on board sound chip portion of the MB. (Which I would choose to disable anyways). All it’s doing is the POST (Power On Self Test) is attempting to “handshake” with the various devices to get a “I’m good” signal before it posts. Anything that does not return this signal causes the BIOS to stop posting and post an error code. I also kind of assume a resistor of this size and value is going to be so slight that it would not matter much if I placed a jumper across it (to complete the circuit) since I would not be using the on board sound… so it’s not going to be “functioning” other than to post that it’s “there” to the BIOS.
I mean as it is the board is dead anyways… the only other idea I had would have been placing a random value resistor across this section as I highly doubt they have schematic’s for this board.
But the best idea is to order a new one off Amazon to test the resistor then send it back for a refund.
Also am I not going to get a biased reading with it in circuit? (I won’t power it on)
It may read too low when in circuit, but that’s still better than guessing a value like zero ohms.
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Oh hello Paul. I have ordered a “tester” motherboard, so I can test the value on this once it arrives.
Hopefully I will be able to solder the replacement part on…
As I recently had a video card with an even smaller SMD capacitor knocked off the PCB. Luckily the missing capacitor was stuck on the board under another component, so I was able to place it back in place and solder it. It was so small though that I had to use a needle to move/place it. And very difficult to solder. (I also could not use a 858D hotair gun as it just blows these tiny SMD’s away)
You may already know this trick to get the best chance of good in-circuit resistance reading.
- With all power disconnected
- Use a jumper wire to make a short across the resistor
- Hold the short in place for 10 or more seconds
- Connect an ohmmeter, noting which polarity you are applying from the ohmmeter, and record the resistance value.
- Use the jumper again to make a short across the resistor
- Hold the short in place for 10 or more seconds
- Connect the ohmmeter with the polarity the opposite of the last measurement and record the resistance value.
- Use the highest of the two measurements as the resistor value (rounding to a stock value)
This process will minimize the impact of capacitance and semiconductors in the circuit.
Here is an update!
So I got the “tester motherboard” I did a test as you suggested (the readings did not change with shorting etc) I got a reading of around 8k ohm one direction and 7.9K the other.
So I kind of thought well I am not sure what the value is unless I remove it, and it dawned on me I have some older dead motherboards I use for parts and I hunted around and found some “physically” matching resistors so I pulled a bunch off and put them in place of the missing resistor. Then I placed it on the solder pads on the motherboard and tested it in circuit to see if I could get them to resister “8k” on the meter to match the donor board’s value on that in circuit resistor.
I did this over and over testing resistors and eventually ended up with a perfect match… sadly since they are so tiny I lost it while trying to solder it in place. I decided to test many others like this and managed to get two values close one was “7.35k” in circuit so I read the actual value as “10.75K” I tried a few others and managed to get one that read as “8.6K” in circuit and the actual value was “13.75k”… I took these two values and kind of split them down the middle to 12.3k… and rounded down a bit to 12K Ohm… then I placed an order for a few values in this range from 11.5-12.5k…
The one that worked was 12K and I got exactly “7.9k” one direction and “8K” the other direction… so I soldered it in place.
Popped the board back into the case and powered it on and it booted up!
So the BEST solution to find the missing part without removing the original part off a “temporary tester board” is to take a reading off the original resistor in circuit. Then apply random value resistors to the one missing the resistor in circuit to try to match that exact value.
Because if I had just placed an 8K resistor there it would have read much lower (around 6k)
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