Yaskawa · A1000Fault Code Uv1Warning
Yaskawa A1000 — Uv1 DC Bus Undervoltage
Occurs when the DC bus drops below the lower limit. Supply sag, phase loss or capacitor ageing is the cause.
Updated: 2026-07-05
Symptoms
- Uv1 on power/load
- Frequent during supply fluctuations
- Stop under load
Probable Causes
- Supply voltage sag
- Input phase loss / loose terminal
- Capacitor ageing
- Soft-charge (precharge) relay/resistor failure
Checkpoints
- Measure mains under load
- Check input phases and terminals
- Inspect the precharge circuit (relay/resistor)
Solution
If mains is healthy, the precharge relay/resistor and capacitors are checked at board level.
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