Is anyone able to identify the 5 pin component that has "C1CB" (I think it's a 1 but it could be I or l) printed on it please? It is on a controller board for a computer monitor. One of them has detonated but there are two more like it on the board. The board has the number E157925. The white connector to the left of the one that blew up (second photo) is the power connector from the power supply which supplies 20V - this was shorted to ground until I cleaned up the expired component. The component has 5 pins (the middle one on the top row is not present).

Visible component

Blown up component

Whole board shot

Update 16/05/2022:

Thanks to Lundin and JRE for pointing out it is a switching regulator. After some work with a multimeter and bench power supply, I was able to figure out that the top left pin is Vout, top middle is ground, and the bottom left pin is Vin. I believe this regulator feeds the main IC on the control board as Vout is connected to some of the pins through some inductors (I was not able to find a datasheet for the main IC). After clearing the busted traces, I connected to bench power supply to the pads and slowly ramped up the voltage - the board started to respond once the voltage was almost 3V so I guess the regulator was at 3.3V. Vin is 5.1V, this rail also supplies the other two C1CB regulators.

I've soldered a "mini 360" voltage regulator set to ~3V to the pads with some mod wires and glued it to the control board - the control board seems to work fine now and the monitor is working properly (it was from e-waste at work). The monitor is an iiyama ProLite XUB2796QSU, incase anyone with the same issue stumbles across this.

I would still be interested if anyone knows exactly what regulator this C1CB is.

  • \$\begingroup\$ What does it matter, your board is fried... the whole cooling area beneath what's very likely a switching regulator has been ripped off. There's no sensible way to repair it. \$\endgroup\$
    – Lundin
    Commented May 13, 2022 at 8:54
  • \$\begingroup\$ It is a switching regulator of some sort - it uses an inductor (part marked LXXXX on the circuit board) to regulate voltage. \$\endgroup\$
    – JRE
    Commented May 13, 2022 at 9:32

1 Answer 1


The IC is an adjustable output synchronous buck converter in a SOT23-5 (SOT25) or TSOT25 package. I labeled your photo to point out the pinning of the IC and the overall layout: enter image description here

The output voltage can be calculated using the feedback resistor divider which on the defect buck converter is: $$V_\mathrm{out} = V_\mathrm{FB} \cdot (1 + (30\mathrm{k}+15\mathrm{k})/(10\mathrm{k}))$$ With a feedback voltage of 0.6V this makes 3.3V output voltage which would make sense. You could confirm this measuring the functioning buck converter output voltage which has a 10k/12k resistor divider. This should make a 1.1V output.

The only sensible IC I could find using the C1CB marking is APSemi APS1006 which I found using s-manuals. While the pinning and general functionality matches, the datasheet suggests a Top Mark different from C1CB:

enter image description here

So you cannot be sure that this is the correct IC. But you can certainly make another IC with the same pinout and feedback voltage work if you really want to.


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