CH341A Important 3.3v Voltage FIX - Motherboard BIOS Programmer

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 KZbin, so big thumbs up to their finding and check out their video: • CH341 Programmer 3.3V ...
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: www.onetransis...
My P5E3 BIOS recover video using this device: • Motherboard with Corru...
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#ch341a #bios #pcdiy

[@christopherjackson2157]

There's a version 1.6 of the ch341a where the voltage issue has been corrected (as of Feb 2022). But I see a lot of eBay listings for the new revision with pictures of the old one, so buyer beware. Always a fan of ur bios content. Thanks!

[@LuumiJuhani]

Great info, so thanks for the headup.

[@intestinal47]

Hi, excuse me for reviving such an old thread. I have to flash a W25Q32BV chip, that operates at 3.3V. I have no access to buy a 1.6+ version of the CH431A, but the CH341B version, will this version work without riks? Thanks

[@xiv3r]

black ch341a has 3.3v and 5v voltage while blue ch341a has only 3.3v fix so no mods required

[@pvb9964]

Unnecessary modification....once connected to 3.3 v bios IC, the volts drop from approx 5 volts to approc 3.3 colts. Modding makes this unit unreliable

[@adifirdaus8204]

i did this, but the data line measuring 3.1 volt, altough the ch341a vcc is 3.3 volt

[@quenchtv5436]

Same here i guess they sent us deffective product wtf

[@TheTechFurry]

That's actually normal, there is a small voltage drop, but you can use the programmer normally

[@quenchtv5436]

@@TheTechFurry still cant fix my asus mobo im planning to buy the latest one but it's too expensive

[@lenslens7379]

Try to put cap 1uF and 100nF at the output of regulator

[@intestinal47]

Dear sir. I have to flash a W25Q32BV chip, that operates at 3.3V. If i buy the CH341B version, will it be safe for this chip? no mods to the programmer are recommendable? Thanks, i have no soldering skills.

[@MACYNET323]

Before flash Bios with soic8 you remove battery and jumper?

[@LuumiJuhani]

Yes you should do it.

[@kovacspis]

How was the X79-UD7? Did you use Ivy-E?

[@LuumiJuhani]

Not tested properly yet, gonna use only sandy-e.

[@kovacspis]

Why sandy-e? What's the goal?

[@LuumiJuhani]

@@kovacspis 3930k + 3820. Add me back David!

[@EpicLPer]

Did this mod and somehow my CH341A made a "sizzling" sound for a few seconds, think something was shorted... it's dead now after a few reading attempts, tho already ordered a new and better programmer.

[@Hudsonkem]

why you guys does not realise that there is a capacitor infront of the out put pin or the regulator that is connected with pin 9?

[@train4905]

Awsome😊

[@SianaGearz]

There's now a new PCB version which has 1.8V, it would be good to look at it. Most BIOS chips on MBs are nominally only 1.8V anyway and only accidentally 3.3V tolerant. By the way there's anecdotal experience of people mindlessly plopping the test clip in 3.3V mode onto 1.8V chips and they're fine, no heat no anything, like what? Colour me surprised, but apparently they are feisty little bois. That X79 has only a 64mbit one? I wonder where they dug that out, i thought 128mbit was common for the longest time. And 3.3V as well huh. Something to keep in mind that the pin source/sink current that CH341a can muster is RIDICULOUSLY low, like 200uA. These will be easily dissipated by ESD diodes on the target chip clamping the real pin voltage to VCC+0.5V, and you don't really need to expect long term damage to the target chip due to this. I'd be really more concerned for whether CH341 will survive that, it's a spectacularly wimpy chip. I understand that it's chip made for and under cost pressure, but it's basically made out of leftover snot. Exceeding VCC on the pins is however not particularly safe for CH341a, which is probably why they went this route of always feeding it 5V.

[@MACYNET323]

How recognize this version?

[@gmt-yt]

Good to know, thanks!

[@quenchtv5436]

Hi can you pls help me what programmer you will recommend to flash bios chip MX25L3206EPI-12G This programmer is a trash i did this but still i get data line 3.1v i wanna buy other programmer

[@pvb9964]

it's now trash because you ruined it it doing the unnecessary modification

[@quenchtv5436]

@@pvb9964 can you explain it further? I tried a tutorial online but i didnt get 3.3 voltage 😔

[@pvb9964]

@@quenchtv5436 watch Sorin in this video "How to program a bios chip - CH341A programmer, no, you don't have to modify it"

[@pvb9964]

@@quenchtv5436 Watch " How to program a bios chip - CH341A programmer, no, you don't have to modify it" by Sorin , Electronics Repair School

[@gymstrengthhakim8453]

I have ch341a, i do this modification but it does not Work.

[@pvb9964]

Unnecessary modification....once connected to 3.3 v bios IC, the volts drop from approx 5 volts to approc 3.3 colts. Modding makes this unit unreliable

[@taiiat0]

cheers.

[@DomeF.]

What awg wire can be used to do this mod?

[@DomeF.]

@Robin Chan ok thank you a lot!

[@blueskies792]

Two wires!

[@Asus-et6ye]

000.000 on meter

[@XantheFIN]

*BAOS*