CH341 Programmer 3.3V Fix | Voltlog #318

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#VoltLog #CH341 #fixed

Welcome to a new Voltlog, if you watched the previous mailbag video I showed getting this CH341 programmer tool for EEPROMS and FLASH chips and my viewers were quick to point out this actually has a design problem regarding the voltage levels it puts out. So it appears there is a 3.3V regulator on board for providing power to the eeprom or flash chip via the zif socket but the CH341 itself is running at 5V which means it outputs 5V signals on the SPI bus.

Someone has reverse engineered this little board and put together a schematic which clearly shows pin 28 VCC connected to 5V but I want to make sure nothing has changed and this is still present. And checking with a multimeter, pin 28 is still connected to 5V USB. Now I’m just gonna power the programmer from a powerbank and probe the data lines and as we can see they are pulled up to 5V.

Connecting a 3.3V rated part for programming might result in damaging that part. You might get lucky, you might have a chip that will tolerate that but in general that’s bad practice and so we’re going to attempt to fix it by simply cutting the 5V line going into the CH341 pin 28 and supplying it with 3.3V from the onboard regulator instead. And the datasheet also specifies that V3 pin 9 should be connected to VCC and 3.3V as well.

That should be an easy to do job, even without any magnification because the packages used on this board are pretty big but since I have a nice microscope that can also capture full HD images, I’m going to do it under the microscope just so you can see what I’m doing and I’m going to use some enameled copper wire for these mods, this stuff is readily available online, I’ll put a link in the description. So one way to do this mod is to lift pin 28 from the pad, add some insulation between the pin and the pad, maybe some kapton tape and solder a thin wire that will connect pin 28 to 3.3V. Messing with the pcb track bringing in 5V to the chip is risky because we don’t have a board view, we don’t know if that track is connected to something else under the chip so it’s best to leave that alone.

So here is a short clip where I lift pin 28 by first adding in some fresh leaded solder and some flux, then I clean with some IPA and add a thin piece of kapton tape. Next some enameled copper wire was soldered to pin 28 and routed up to the middle pin of the regulator which is the 3.3V rail.

Next I did the same connection for pin 9, but this time there is no need to lift the pin from the PCB because it’s just connected to a bypass cap. To finish this off I would recommend adding some kind of glue to the wires to prevent them from breaking-off. I use some of this transparent silicone adhesive, apart from the fact that it cures pretty slow this is really nice stuff, I highly recommend you get yourself a tube of this and you will find a link in the description below the video

It was a quick 5 minute job to do this mod, really easy and like I said, there is no need for magnification. Now let’s check the voltages we get… and we have 3.3V on pin 28 and on pin 9, that’s good. And let’s check the data pins, yup they are now pulled up to 3.3V which is what we want. So I call this a success and a perfectly good example of the power of the youtube community, oftentimes I’m getting really useful feedback from my viewers and I appreciate that.

[delfin]

Before this mod, I got consistent verify error on GD25Q64C. Now after this mod, my CH341A works perfectly, thanks!

[jessechen]

Hi. I just wanted to comment on this video. I also followed and used a USB power bank. This did output around 4.7 V to most pins, including most of the ZIF socket But when I checked VCC pin it was 3.3 V. So, I
then plugged the CH341A into computer. I checked voltage at socket #8 which is VCC to the chips. The output is 3.3 V, correct. All other sockets are at 0 V, nothing at 5 V. I am using it without modification. Test the VCC socket for V when connected to PC with proper driver. You may not need to do any modification.

[KnurdMonkey]

So this means it is a design flaw and need to be fixed in order not to burn ICs? Did I understand right?

Thanks a lot for your video and clear images. Much appreciated.

[aaaronmiller]

OMG been looking for this video for EVER! thank you soooo much! i knew this was what I wanted to do but finding a concise and simple explanation of how to do it eluded me, you da MAN!

[frankschannel]

Super job - well produced, clear and concise! Much appreciated. Well deserved thumbs up given!

[AliYassinToma]

Useless mod btw.. when u insert the chip it will switch to 3.3 instantly also only 3 pins are 5 the rest are 3.3 already and u can verify that with ur multimeter

[brandonpiper]

Hi! Is there a way to add a switch to easily switch back and forth from 3.3V to 5V?

[elgranelectron]

Does the 1.8v adaptor still work after 3.3v moding?

[korishan]

Thanks for the video. I was hoping this would solve my issue. Problem is, now the CH341 chip gets *very* hot while connected. Also the status led (opposite side of the board power led) doesn't come on now. This is without the bios chip connected. Is the CH341 fine? I double checked the connections and they are correct according to the video. I'm at a loss here 🙁

[retezankarol]

Hey, nice video!
I'm confused. I checked the voltage as you did in video and I have the same result.
In zif socket on pin 8 (VCC) I have 3.3V....
It's necessary to do this modification ?
And if you want to make some JTAG from that pins you check, you have 3.3V pin.
Anyway i liked the video ;)

[Commut]

Well done! Subscribed. If you would like to make (very) popular videos one way is to show the full process of flashing Thinkpad (because they're so popular) BIOS with Coreboot, Libreboot and especially with stock firmware to recover disabled notebooks. Many passwords are simply forgotten and the machines Ebayed without correcting the problem.

[pinktoebeans]

VoltLog, can I pay you to transfer me a modded programmer please?

[andreallridge]

Great video! One word of advice to anyone trying this fix: Be VERY careful when lifting up the pin that is later bridged using the additional wire. When I tried to solder the wire onto the pin I lifted before, it broke off. It is likely that I damaged it already when lifting it up, but as a result it was impossible to solder any wire onto the chip and the whole thing is now toast. Thankfully, these things are cheap, so I'll just order another one, but better to avoid this happening in the first place.

[rexjuggler]

Okay, this is really funny. This video shows how to bring level down to 3.3 V, but DrShock has a Youtube with his CH341 only providing 3.3 volt and shows how to modify his version of the board to bring it up to 5.0 V. Apparently, DrShock needs the 5V for automotive chip programming, while the 3.3V is needed for PC BIOS chips. Perhaps you guys can just trade boards? I'd say there are 2 versions out there and just be sure you get the one for your particular chip programming application. This is very interesting topic, though. I used a chip programmer with a sewing needle to 3.3 V power to re-program a 2015 Apple MacBook Prom to unlock it with chip in-place on board with a ribbon cable that attached to a SAM socket directly on the logic board. Nice and clean and no soldering. Just had to hold the pin steady for a few minutes to do the read, and then again to do the write. I'm typing this on that computer. Battery and power disconnected from logic board, sewing needle attached to a 3.3 V lead from an old PC power supply.

[valtuber]

Great tutorial, buddy! I've got the same ch341a programmer, I know where
to start from, but just wanted to confirm, other hackers have used it
successfully. Thanks!

[papipapi]

Thank you very much! my CH341B worked badly for writing a Winbond 25Q64FV now its works really well !!! my problem is solved thanks you! ( I buy a 341A on ebay and i receive a 341B, but it's work now!!)

[MegaPaul]

I have a couple of these and just checked them and both have 1.5v on the data lines, I assume they have fixed the design error

[jarnovilen]

Wrong! The data lines are 3.3V when using the device. The voltage on the data lines WITHOUT connection is about 5V but as soon as you connect it to a chip and start communicating the voltage in fact IS 3.3V. So the modification is not only stupid it is also totally useless and even harmfull!

[xPIT]

Thanks, very useful! I did the mod just now.

[jensgoerke]

I was thinking of putting a dab of white/florescent paint near pin 1 of the socket to make things easier - in a hurry the lever alone might not be enough of a reminder.