# An old monitor that forgets to listen

Published 2026-10-10 · monitor, DDC/CI, Windows, hardware · https://home.tigran.manukyan.dev/notes/monitor-that-forgets-to-listen.html

**TL;DR:** An old DVI monitor that stays black after boot or after a long signal gap can be woken by switching its input over DDC/CI (VCP 0x60) to VGA and back to DVI with NirSoft ControlMyMonitor, run from a scheduled task at logon.

My second screen is a 22-inch panel with about 35,000 hours on it, fed over DVI. After every boot it stayed black with the backlight on. Windows saw it, the cable was fine, and unplugging it fixed it. That got old fast.

## Narrowing it down

The monitor answers DDC/CI, so I could ask it what it thought was going on. When stuck, it reported the right input (DVI) and a locked vertical frequency of 0 (VCP `AE`), so it simply wasn't listening.

- Reproducible: Win+P "PC screen only" for 40 seconds, then Extend. A one-second gap (Win+Ctrl+Shift+B) does not trigger it.
- Re-selecting DVI does nothing. Restarting the signal from Windows does nothing.
- Switching the input to VGA and back to DVI wakes it up every time.

## The workaround

NirSoft's ControlMyMonitor can write VCP codes from the command line. VCP `60` is the input source; on this monitor 1 is VGA and 3 is DVI.

```
ControlMyMonitor.exe /SetValue "\\.\DISPLAY2\Monitor0" 60 1
timeout /t 2
ControlMyMonitor.exe /SetValue "\\.\DISPLAY2\Monitor0" 60 3
```

The monitor ignores writes while it's switching, so the real script re-sends until reading `60` back confirms the value, then checks that `AE` is no longer 0.

It runs from a scheduled task at logon, with a second trigger a minute later as a safety net. 26 boots in a row came up stuck, and the script woke the screen on the first try every time.