As my CH341A video was quite popular when I repaired the ASUS P5E3 Premium using this device, I thought about sharing this 3.3v voltage fix with you my followers. The issue with the CH341A is that not all of the pins that are connected to the target BIOS chip output 3.3v, actually half of the pins output 5V when most of the BIOS chips are rated for 3.3v. This can cause issues when you try to access BIOS chips using this device, and in the worst case it could damage the target BIOS chip completely. I came across noticing this when I messed around with the X79-UD7 BIOS downgrade.

I encountered this mod on VoltLog's channel here on Youtube, so big thumbs up to their finding and check out their video:    • CH341 Programmer 3.3V Fix | Voltlog #318  

The idea of the process is to reverse engineer the device and make the CH341A controller chip of the device to operate at 3.3v instead of the stock 5 volts. This happens by lifting the VCC pin (pin 28) and soldering that lifted pin to the center leg of the U1 mosfet, the side that has 3 legs on that component. Then on top of that you need to solder another wire from the opposite side of the U1 mosfet to Pin-9 of the CH341A chip. This time you don't need to lift the target pin of the CH341A.

After this all of the data lines should output 3.3v instead of 5V and the device should work flawlessly. You can confirm the voltages by inserting the device to laptop or power bank USB port and by measuring the voltages with a multimeter, even before and after this modification.

CH341a schematic and drivers etc: https://www.onetransistor.eu/2017/08/...

My P5E3 BIOS recover video using this device:    • Motherboard with Corrupted BIOS? FIX ...  

Join my Patreon discord:   / luumi  

#ch341a #bios #pcdiy