The amplifier card is the electronic bridge between your control system and the servo or proportional valve — and it’s one of the most overlooked components when a hydraulic system starts acting up. Because a failing amp card can produce symptoms that look mechanical, it often gets ruled out last, after time and money have already gone into inspecting the valve itself.
Here are the warning signs that point to the amp card rather than the valve.
Erratic or Inconsistent Valve Response
If the valve responds correctly one moment and lags, jumps, or ignores the command signal the next, the issue is often in the amplifier’s signal conditioning rather than the valve’s mechanical stage. Loose connections, degraded solder joints, and thermal-sensitive components on the card can all cause response that changes from cycle to cycle.
Drift, Null Offset, or Calibration Loss
Amp cards maintain the null bias and gain settings that keep a valve centered and responsive. A card that can no longer hold its calibration — requiring frequent re-zeroing or drifting out of spec shortly after adjustment — usually points to a failing potentiometer, aging capacitor, or feedback circuit rather than a problem with the valve itself.
Overheating or Visible Component Damage
A card that runs hot to the touch, trips its own thermal protection, or shows discoloration, bulging capacitors, or burn marks around a component is a clear sign of electrical failure. This is one of the few amp card issues that can often be spotted with a visual inspection before you ever put the system back into service.
Communication or Command Signal Faults
If the controller shows a valid output signal but the valve doesn’t respond at all, the amp card’s input or output stage is a likely point of failure. Intermittent faults, dropped signals, or a card that only works after being power-cycled are strong indicators that internal components are failing under load rather than at rest.
Why It’s Worth Testing the Card Separately
Because amp card symptoms overlap so heavily with valve symptoms, replacing or rebuilding a valve without testing the card first can leave the original problem unresolved. Performance Servo bench-tests amp cards under simulated load to confirm whether the card, the valve, or both are contributing to a system fault, so repairs are targeted at the actual point of failure.
If your system is showing erratic response or calibration drift, Performance Servo can test your amp card alongside the valve to pinpoint the real issue before any repair work begins.