Brother 'Print Unable 0B' — High-voltage fault (try the drum first)

What this error means

A high-voltage power supply fault — but here's the field wisdom the service manual buries: a worn drum unit shorting the high-voltage supply triggers 0B too, and a drum is a $60–120 part versus board-level surgery. Test the cheap explanation first.

Symptoms

• 0B on a laser model
• High-mileage drum unit

Try this first (safe DIY steps)

1. Power cycle once
2. Clean the corona wire (green tab) and check drum contacts
3. THE test: try a known-good or new drum unit before authorizing board repair

Safety: power off before any physical intervention. Never bypass covers or interlocks — fuser areas run hot enough to burn.

When to call a technician

If a fresh drum doesn't clear it — HVPS/board service; on small units, compare with replacement cost.