Woodward TechJet 50 Proportional Valve Repair - Glass Manufacturing, Jambusar

A leading float glass manufacturing plant in Jambusar experienced a critical production breakdown when their Woodward TechJet 50 proportional valve controller, controlling the main tin bath oil flow regulation system, failed completely during second shift operations.

The valve controller stopped responding to PLC commands, causing immediate loss of precise temperature control in the molten glass tin bath - a critical parameter that directly affects glass quality and surface finish.

The plant's maintenance team reported Error Code E-47 (driver circuit failure) and E-52 (position feedback loss) on the diagnostic display, along with complete loss of valve spool position indication on the SCADA system.

The production impact was severe and immediate.

Without precise oil flow control to the tin bath heating system, the plant had to shut down the entire float line within 90 minutes to prevent glass quality defects and potential equipment damage from temperature fluctuations.

Each hour of downtime represented a loss of approximately 45 metric tons of float glass production, translating to revenue loss exceeding Rs.

Upon receipt at our Vadodara facility, our specialized valve controller repair team immediately began comprehensive diagnostics on the TechJet 50 unit.

Visual inspection revealed burn marks on the main driver PCB near the high-current output stage, and thermal imaging confirmed hotspot areas around the MOSFET driver section.

Using our Tektronix oscilloscope and Fluke precision multimeter, we traced the fault to catastrophic failure of the primary PWM driver IC (TI UCC27524) which had shorted internally, taking out four parallel-connected IRFP250N power MOSFETs in the H-bridge output stage.

The position feedback circuit had also sustained collateral damage - the differential amplifier section built around OP284 precision op-amps showed offset drift beyond specification limits, and the LVDT signal conditioning circuit had damaged resistor networks affecting linearity.

Our repair approach involved complete replacement of the failed driver IC, all four output MOSFETs with genuine Infineon parts, and rebuilding the gate driver isolation circuit with new optocouplers (6N137).

We replaced eight SMD ceramic capacitors (47uF 50V X7R) in the output filtering stage that showed ESR degradation, and rebuilt the LVDT signal conditioning section with precision 0.1% tolerance metal film resistors and new OP284 op-amps.