I finally got around to 3D printing a GPS spacer for my 3DR solo. This is also known as the “cardboard mod” around the forums/Facebook groups. What this spacer does is puts some space between the copper foil and the GPS PCB. 3DR made a mistake when designing the GPS module and spaced it to close to the PCB, meaning it’s not as effective.
Note: DO NOT use a “Revision A” GPS. These have a known design flaw and are not reliable. You can check what you have by the writing on the GPS PCB.
The first step is to head over to thingiverse and download the model designed by @Tunames. The thingiverse page is here. Just print it out and begin taking apart your solo. I’ll briefly cover the installation procedure below. It should go without saying, every time you take Solo apart no battery should be connected! (unless you know what you’re doing) It’s also not a bad idea to take the GoPro off too.
Start by undoing all 4 screws underneath where the battery normally sits. Then get a small flat-head screwdriver (ideally a rubber spudger) and gently pry off the GPS cover. Underneath the GPS cover you should find 3 screws, undo all 3 and slowly lift up the battery tray. Be careful of the GPS cable, unclip it as soon as you can.
Now flip the battery tray over and you should see a black tape looking cover. Peel it off, being careful not to destroy it. It’s copper shielding that’s really important for keeping out interference. Undo all three screws holding the GPS in and sit them aside. Place the 3D printed spacer with the flat side out.
Tip: If the tape loses it’s stickiness use a generous amount of glue stick to hold it in place. You do not want the tape coming loose!
Now, put everything back together in the reverse order. When you turn Solo back on you may not notice an immediate difference. You might get a slightly faster lock, but in general the GPS should be more reliable.