10 — DIAGNOSTICS · 2026
The $15 Grill Fix
A Traeger's display died. A bench rig proved the control board was fine and the panel had failed. A $15 replacement panel fixed it, not a new board.
- Built
- A bench rig that tests a grill's display apart from its control board.
- Stack
- Raspberry Pi Pico, software SPI, ten controller init sequences, diagnostic test patterns.
- State
- Fixed with a $15 replacement screen.
DONE · UPDATED 1 OCT 2026
Diagnosed 2 Aug 2026: the screen had failed (likely a bond failure); the control board was fine. A $15 replacement screen fixed it.
Carter Barnes · cloud engineer, federal Azure · Contact
What it is
A Traeger D2 controller lit its backlight but painted no pixels. Two candidate faults look identical from the outside: the LCD panel, or the main board driving it. Replacing the wrong one costs money and does not fix the grill.
The panel is a 128×64 ST7565P chip-on-glass module, an unbranded panel compatible with a Newhaven part, so a blank screen has three causes that look the same: dead glass, the wrong contrast, or the wrong init sequence. The rig existed to separate them, not to display anything.
Verdict: the panel was dead and the board was fine. A replacement panel at about $15 went in, and the display works again.
How it works
- Bench rig
- A Raspberry Pi Pico drives the panel directly over software SPI, with the grill out of the loop. 3.3 V only: 5 V on any line destroys the glass.
- Pinout
- Mapped the HOPESUN carrier's 12 pads and confirmed the pinout, measuring the supply, reset and ground pads directly. The seven that matter: clock, data, supply, A0, reset, chip select, ground.
- Contrast sweep
- 0 to 255 in steps of 8, held 700 ms each. A blank panel at one contrast value proves nothing.
- Ten init sequences
- Ten builds, each a different controller init, from the Newhaven sequence down to the ST7567 and UC1701 dies that compatible panels often turn out to be.
- Test patterns
- Each one names a failure: row and column sweeps for dead driver lines, page bands for addressing faults, and command 0xA5, which lights every pixel from the controller's own logic and ignores the frame buffer.
- The fix
- A Newhaven NHD-C12864A1Z, the documented equivalent of the original panel, for about $15.
By the numbers
- $15
- replacement panel instead of a new control board
- 10
- controller init sequences tried; none drew a pixel
- 12
- carrier pads mapped to a confirmed pinout
- 128×64 px
- ST7565P chip-on-glass panel
What I learned
- 01
Ask which half is broken
The default path is to replace the expensive assembly. One evening on a bench turned a several-hundred-dollar swap into a $15 one.
- 02
Drive the screen directly
With the rig feeding the screen itself, a blank screen can't be the board's fault. This one stayed blank, so the screen had failed, most likely where the glass connects to its driver chip.
- 03
The rig works for the next panel too
The rig now drives that class of panel for anything else that comes across the bench.
What went wrong
- 01
Counted from the wrong pad
Early tests failed because I counted pins from the backlight pad instead of pin 1. Every panel looks dead when the wires are one off.
