Sprinkler Controller Display Dead: Transformer or Fuse Check

Blank display on a sprinkler controller with a live outlet means either the transformer failed or an internal fuse blew.

Diagnostic Steps

1. Open controller, locate 24VAC terminal strip (two wires labeled 24V or similar).
2. Measure AC volts across them. 0V = bad transformer. 24V = transformer OK.
3. If 24V present, check for small glass fuse on circuit board (0.5A–1A, 250V). Replace if blown.
4. If no fuse or fuse OK → controller board failed.

Transformer Replacement

• Match voltage (24VAC) and VA rating (usually 20–40VA).
• Available at Home Depot, Lowe's, irrigation suppliers (~$20).
• Wire: 110V primary (black/white), 24V secondary (two yellow).

Brand/Model Needed for Fuse Location

Not all controllers have fuses. Provide brand/model for specific guidance.

Start with the 2-minute voltage test—it tells you which $20 part to buy.