Troubleshooting#

The installer can't find or connect to the board#

• Use Chrome, Edge, Opera or Firefox (151 or later) on a computer, not Safari or a phone.
• Try a different USB cable: many only carry power.
• On Windows or older macOS, install the driver for the board's USB chip, then plug the board in again: CH340/CH341, CP210x or FTDI. The chip's name is printed on it, next to the USB socket.
• Hold the board's BOOT button while the installer says "Connecting".

I can't open opendmd.local#

• Make sure your phone or computer is on the same WiFi as the player.
• Some devices and networks don't support .local names. Use the player's address instead: find it in your router's list of connected devices, or take the SD card out and power the display on, and the panel shows its address.
• If the player can't join its saved WiFi (a new router, a changed password), plug it into a computer, open the installer, click Install and choose Change Wi-Fi. Or join the OpenDMD-Setup network it opens and enter the new details there, as in WiFi without the installer.
• Two displays with the same name. Every display is called opendmd until you rename it. When a second one joins your network with the same name, one of them moves to opendmd-2.local (and it may be the one you had first). Open opendmd-2.local or the display's address, then give each display its own name in Settings → Device → Network (a name another display already has is refused). Settings → Device → About shows the address a display really has.

The panel says there's no card, or the card can't be read#

• Check the card is pushed fully into its slot.
• The player needs a FAT32 card. If the web app's Now view says the card needs FAT32, use Format card… there (this erases it), then add your GIFs again. See The SD card.
• The player keeps checking for a card, so you don’t need to restart it after swapping cards.

The display resets or flickers when it's bright#

The power supply can't keep up at high brightness, especially on mostly white pictures. Lower the brightness, or lower Maximum brightness in Settings → Playback if you raised it.

Some LEDs show the wrong colours on certain pictures#

If a few dots come out the wrong colour on some pictures but not others, the panel may be fussy about timing. Open Settings → Device → Panel timing and press Test panel timing. The panel shows some test pictures, switching between A and B (the letter is in the bottom corner): pick the one that looks clean and it is saved. If both have dots, it tries a second setting the same way. Stop puts everything back, and so does leaving the page for two minutes.

If neither helps, change the settings by hand, one at a time: Clock edge, then Latch blanking, and only then Driver chip. Each change is tried for a minute: press Keep if it looks better, or let it go back by itself. The driver chip needs a restart to try, and if the panel goes dark, just wait and it comes back on its own. Reset to defaults puts everything back. After trying a different driver chip, switch the display off and on before judging the result. If nothing helps, the panel itself may be faulty.

Settings says "Card running at reduced speed" or shows card errors#

The card is wearing out. The player keeps going as best it can, but replace the card soon and copy your GIFs over.

The web app won't load, or looks broken#

The player always has a simple backup page at http://opendmd.local/setup: WiFi, basic playback settings and a restart button. To put the web app right, run the installer again with Erase device unticked.

A WiFi update didn't finish#

If the board's light blinks fast after a firmware update, it is waiting to finish installing from the SD card: make sure the card is in and leave it. If the player still doesn't come back, run the installer again with Erase device unticked.

Starting over#

Running the installer with Erase device ticked wipes the board back to a fresh install: WiFi details, settings and a forgotten security key all go. Your SD card, GIFs and playlists are kept.

Building the display#

The Assembly section of dmdos.net shows each step of the build with a photo.