I've just bought a very bad quality D1 mini board. While soldering pins, I made rookie mistakes and I had to desolder, then (really bad) pads got detached from pcb. I certainly don't have experience replacing pads and keeping through connected holes right, so I figured why not connecting ESP23F directly to JP, bypassing PCB tracks.

By simply visually checking the tracks on the PCB, I can't tell if all ESP12F pins are directly and one-to-one connected to each pin hole, moreover, the top side of the board seems simple enough but I'm not so sure about the bottom side.

So, I definitely can send the board to the trash and buy a new one (why not, they are cheap even in Argentina), but where is the fun in all that?

That's why I'm asking for any advice on how to solder JP given the missing pin hole pads.

I'm might be wrong, but if this can be performed by soldering ESP12F JP to pin hole/headers on the top side, and soldering the unconnected tracks in the bottom side with thin wires to the right JP on the top, it would be helpful to know which are the correct connections.

Edit: Pictures of the repair process

  • \$\begingroup\$ It might help to include pictures of the boards you are referencing. In general, you can divine out the correct connections with a DMM. \$\endgroup\$
    – uint128_t
    Commented Apr 27, 2017 at 1:14
  • \$\begingroup\$ What the heck is a "D1 mini"? \$\endgroup\$ Commented Apr 27, 2017 at 1:55
  • \$\begingroup\$ @ConnorWolf, it is this \$\endgroup\$
    – Dario
    Commented Apr 27, 2017 at 1:56
  • \$\begingroup\$ @uint128_t please check this out \$\endgroup\$
    – Dario
    Commented Apr 27, 2017 at 2:01

1 Answer 1


No that I understand what you're trying to do (rather, what you have already done, as it appears from your images), no, you cannot simply bridge each pin to the pad it is next to. It seems that since you have already gone ahead and done the soldering, my answer is rather pointless, but I will go ahead and answer anyway for posterity's sake...

Your question could be easily answered by looking at the schematic: most of the pins have a 1:1 correspondence, except for ADC/A0 and power supply pins. From your images, it appears you have bypassed the ADC divider (not so bad), misconnected several GPIOs (16, 14, 12, 13, and 15), connected GPIO15 to GND (not good), and connected 5V to ground (very not good). If you have powered up the unit in this state, I suspect it will be very unhappy.

Additionally, as I can't tell which tracks have been lifted where, it's possible that vital circuitry has been disconnected from the pins. In short, scrap the board and start over. All in all, not a bad board to learn how to solder on, a $3 board isn't much of a loss. In the future, patience and reading the schematic are your friend.

Now, if you do want to try and repair it:

First, look at this schematic. This is the official schematic from Wemos, and hopefully matches your board (no guarantees though, that's the consequence of cheap dev boards).

From the schematic, here's how things are pinned out (with pinouts flipped where logical):

   JP2 |    ESP-12F    | JP1
   RST | RST        TX | TX
    A0 | ADC        RX | RX
GPIO16 | EN      GPIO5 | GPIO5
   3V3 | 3V3       GND | +5V

From this diagram, you should be able to figure out what needs to be bridge to what. For the 5V pin, you'll have to either scrape the trace clean or wire it to the regulator input (although maybe you don't need the 5V pin). May also have to scrape for A0: A0 is different than ADC!

  • \$\begingroup\$ You be surprised how much 3 dollars is worth in some countries. Op says it's still cheap but ymmv. \$\endgroup\$
    – Passerby
    Commented Apr 27, 2017 at 3:17
  • \$\begingroup\$ Thanks for the answer and the suggestions. I actually considered looking for schematics, but that wasn't enough since I wasn't able to understand how to proceed from there to the actual board. I never powered the board, though, because I was just giving my idea a try, until I found out in the schematics that there was no way to fix the board without the proper guide. May be you can point me in the right direction by posting a link to the schematics you consider appropriate to follow. \$\endgroup\$
    – Dario
    Commented Apr 27, 2017 at 3:18
  • \$\begingroup\$ @Passerby Hmm, fair enough. I just figured that if I can buy a D1 mini for $3 in the states while most other dev boards are $20+, it would be cheapish elsewhere as well. \$\endgroup\$
    – uint128_t
    Commented Apr 27, 2017 at 3:19
  • \$\begingroup\$ @Dario It may be still possible to fix the board, but it would require another round of rework, and it appears the board is in pretty bad shape already. If you really want to try and fix it, take the schematic and a DMM and carefully figure out what is still attached to what and then where it should be attached to. \$\endgroup\$
    – uint128_t
    Commented Apr 27, 2017 at 3:20
  • \$\begingroup\$ @Passerby this is actually a $15 board in Argentina, is not the cheapest but.. it can be ruined just to learn something. May be the cheapest is ESP01 at $10. Nothing is cheap around here, sadly, try and learn has its costs \$\endgroup\$
    – Dario
    Commented Apr 27, 2017 at 3:25

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