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Most NESRGB boards sold between December 2016 and October 2017 have a fake voltage regulator IC fitted.
How to identify.
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Genuine
The genuine part has clear printing and a circular mould marking in the centre of its package, the text depends on manufacture date.
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Fake
The fake part has poor quality printing, no mould marking, the text always reads HU1625 042.
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The part number is MCP1703T-3302E/MB manufactured by Microchip. The fake is probably a Chinese LM1117 or similar (eg. AMS1117-3.3).
The fake part is not a direct equivalent for the genuine one. The genuine part is designed for stability with a ceramic output capacitors in the 2-10 uF range. The fake part is probably meant to have an electrolytic or tantalum output capacitor in the 10-100 uF range. In some cases the fake voltage regulator will oscillate. Here's a video of this symptom.
Solution
The solution is to replace the fake voltage regulator with a genuine part. To remove it from the PCB you can use a hot air rework station or a soldering iron. The method for the soldering iron is to add extra solder to each of the three pins, then hold the iron in such a way as the tip is making contact with all three pins simultaneously. The thermal connection between the centre pin and the tab will eventually cause the solder to melt. Then the part will slide off the board.
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There is a metal tab connected to middle pin.
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Last updated 15/2/2023
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