Toro DDC-6: Blank Screen with AC Power, Works on Battery Only

Toro DDC-6 (4-5 years old): screen blank with AC adapter. Replaced battery - works on battery alone, but with AC connected, weird symbols appear then blank. Reset didn't help.

Transformer Voltage Test

Check transformer output with multimeter on VAC:

• US standard: 22-26 VAC
• Australia (where this may be): Verify local standard

Diagnosis

• Transformer reads correct voltage → Controller microprocessor or LCD display failed → Replace controller
• Transformer reads low/zero → Replace transformer

Why Battery Works But AC Doesn't

Battery powers only the microprocessor/memory (low current). AC transformer powers the microprocessor PLUS valve output drivers (higher current). A failing transformer or controller input circuit can't handle the load.

Replacement Options

Consider Rain Bird ESP-RZX or Irritrol Rain Dial - more reliable than Toro DDC series.