A Possible Solution to USB Problems

[German_EE]

The USB interface is quite robust but it IS possible to kill it if you try hard enough, in this case an incorrectly wired plug sent 12V into one of the data lines and now the FTDI chip has a hole in it. This particular chip is also obsolete and there are no pin compatible replacements even if I had access to a hot air station to remove it. Instructions from the device owner were to repair the unit if at all possible.

Step forward the Polulu CP2104 https://www.pololu.com/product/1308

This little module uses the Silicon Labs chipset with a Micro-USB in and 3.3v TTL out. You can use either hardware or software handshaking (or even none at all) and you even get 5v and 3.3v outputs to power the rest of the PCB. The module is so small that you can remove a type B USB socket and fit this little PCB into the board area that is left. Software drivers are easy to install and worked first time, all I needed to do was change the COM port number.

Anyone using one of these modules has a little work to do tracing the data I/O lines from the FTDI chip then either cutting the two PCB traces or, in my case, removing two 1K resistors. The new module then supplies a connection using two jumper wires and the existing traces.

Recommended.

[magic]

You don't need hot air to remove SOP and similar packages

BTW, which FTDI chip it is?

[German_EE]

The FTDI chip that died was an FT232BM with 32 pins, removing that without either hot air or chipquick would not be fun!

[magic]

Damn quads

A few years back as a total noob I have actually desoldered one, but destructively and the PCB needed some repair too

[fzabkar]

The CP2104 chip can handle I/O voltages as low as 1.8V, if its Vio input is properly powered. This feature is becoming indispensible with the newer LVTTL interface voltages.

https://www.silabs.com/documents/public/data-sheets/cp2104.pdf

Since you are modifying your adapter, I would add 1.8V and 2.5V LDO regulators, plus a rotary selector switch or jumper block. Then you will be able to support 1.8V, 2.5V and 3.3V LVTTL I/O.