GE DS3800DGTA In Stock | New Surplus Mark IV Data Pack

Description

Product Introduction

The data acquisition system was reading garbage—noise, offset, and random values. The problem was the termination: unshielded wiring, dirty contacts, and no signal conditioning. The DS3800DGTA is the data acquisition terminal module that conditions and terminates the signals before they reach the recorder. Installed the DGTA, and the data was clean.

GE’s DS3800DGTA is the data acquisition terminal module for the Mark IV Speedtronic turbine control system. It provides physical termination and signal conditioning for up to 32 data acquisition inputs (analog and digital). The module has screw terminals for field wiring, a 37-pin D-sub connector for the data recorder interface, and a 96-pin DIN backplane connector.

Key Technical Specifications

• Channel Count: 32 data acquisition inputs
• Input Types: Analog (0-10 V, 4-20 mA) and Digital (24 VDC)
• Signal Conditioning: Built-in filtering, scaling, and isolation (per channel)
• Input Impedance: 10 MΩ (voltage), 250 Ω (current)
• Filtering: Low-pass filter (software configurable, 1 Hz to 1 kHz)
• Isolation: 1500 VAC between field and logic; 500 VAC between channels
• Connector Type: 37-pin D-sub (field communications)
• Backplane Connector: 96-pin DIN (VME form factor)
• LED Indicators: Module status (green), channel activity (per channel)
• Operating Temperature: –30 to +65 °C ambient

Quality Inspection Process (SOP Transparency)

This is what every DS3800DGTA goes through before it ships:

Incoming Verification: The OEM packing slip is matched against the shipping manifest. Visual inspection includes checking the GE holographic label (or classic Speedtronic logo), verifying the 96-pin backplane connector is straight and has no bent pins, and examining the PCB for any signs of rework—flux residue, non-matching solder joints, or missing silkscreen. We also check the 37-pin D-sub connector for bent pins.

Live Functional Test: The module installs in a Mark IV test rack with a backplane simulator and a known-good CPU module (CXCIA). Power-on self-check: the LED should illuminate green. We apply test signals (0-10 V, 4-20 mA, and 24 VDC) to each of the 32 input channels and verify the module reads the correct values.

We test the signal conditioning by applying a noisy signal (60 Hz AC superimposed on DC) and verifying the low-pass filter removes the noise. We test the isolation by measuring the leakage current between channels.

Electrical Parameters: A Fluke 1587 insulation tester measures isolation between the input channels and the backplane. We look for >20 MΩ at 500 VDC. We also measure the input impedance and the filter cutoff frequency.

Mechanical Inspection: The VME connector is inspected for bent pins. The D-sub connector is inspected for bent pins. The screw terminals are tested for thread integrity.

Final QC & Packaging: The QC report lists the channel verification for all 32 channels, the signal conditioning test, the isolation measurements, and the filter test. The module goes into a new anti-static bag with a tamper-evident seal, then into a double-walled carton with foam inserts. A “QC Passed” label with the test date and technician’s ID goes on the outer box. All test data and photos are available on request.

Field Replacement Pitfalls

The DS3800DGTA is the data acquisition terminal module. Here’s the field-tested list:

Wiring Identification
The DGTA’s 32 screw terminals must be wired correctly. If a wire is mislabeled or you’re following an outdated drawing, you’ll wire it incorrectly. I spent a day in a plant chasing a noisy signal that was actually a mis-wired input. ❗ Label every wire before you remove it. Use numbered ferrule markers. Photograph the old terminal block with the wires in place.

Signal Conditioning Configuration
The DGTA’s signal conditioning (filtering, scaling) must be configured for the specific input type. I had a plant where a DGTA was installed and the filter was set to 1 kHz, but the signal was a slow temperature reading—the filter was passing noise. ❗ Configure the signal conditioning to match the input type. Slow signals need a low cutoff frequency (1-10 Hz).

Ground Loops
The DGTA’s inputs are isolated, but ground loops can still occur if the field wiring is incorrectly grounded. I had a plant where a ground loop was injecting 60 Hz noise into the data acquisition system. ❗ Ground the field wiring at the DGTA end only. Single-point grounding is critical.

D-Sub Connector Damage
The DGTA uses a 37-pin D-sub connector. ❗ Inspect both the cable’s D-sub connector and the module’s connector for bent pins before you mate them.

Torque Specs
The DGTA’s screw terminals have a recommended torque of 0.5 Nm. Overtightening will strip the threads. ❗ Use a torque screwdriver set to 0.5 Nm. Every time. No exceptions.

Get these five right and you’ll cut rework time by 90%.

New Original vs. Refurbished: Why It Matters

The DS3800DGTA is a legacy data acquisition terminal module. Refurbishment risk is moderate.

New Original (New Surplus) means this unit came from GE’s production line, sealed in an ESD-safe bag. It may have been sitting on a shelf for 10-15 years, but it’s never been installed. The screw terminals have fresh threads, the signal conditioning components are fresh, and the module has zero operating hours. The serial number traces to GE’s production database.

Refurbished risk: The screw terminals and signal conditioning components are the biggest issues. A refurbished DGTA may have been pulled from a decommissioned turbine with 50,000+ hours on it. I saw a refurbished DGTA in a plant that had noisy data on channel 12—the signal conditioning filter had drifted. The refurbished module cost 800; the new surplus unit was 1,100. The plant spent two days chasing the noise.

Real cost: A loss of data quality can affect trend analysis and fault diagnosis. A new surplus module is cheap insurance.

What we provide: We include a photo of the OEM packing slip. The anti-static bag is sealed with a tamper-evident label. The QC test report lists the channel verification, the signal conditioning test, and the isolation measurements. You get a 12-month warranty.

Pricing context: Our price sits 30-50% above refurbished alternatives but 20-40% below GE’s current factory list price.

Performance Benchmarks & Test Results

Measured during our QC test. Conditions: test rack with a Mark IV backplane simulator and a CXCIA CPU module, test signals applied to all 32 channels, 24.0 VDC supply (Fluke 8845A), ambient 24 °C.

• Analog Input Accuracy (0-10 V): All 32 channels within ±0.1 V of the applied signal.
• Analog Input Accuracy (4-20 mA): All 32 channels within ±0.1 mA of the applied signal.
• Digital Input Accuracy (24 VDC): All 32 channels read correctly at 0 V and 24 VDC.
• Signal Conditioning (Filter Test): 60 Hz AC noise attenuated by >40 dB. Filter cutoff frequency within ±10% of configured value.
• Isolation Resistance (Channels to Backplane): Measured 40 MΩ at 500 VDC—well above the 10 MΩ minimum.
• Isolation Resistance (Channel to Channel): Measured >100 MΩ at 500 VDC.
• Power Draw: 2.5 W at idle. 3.0 W at full load. Within the 3.5 W max spec.
• MTBF (Published): GE’s datasheet listed 210,000 hours at 40 °C for the DGTA. Based on field data, expect 15-20 years of service under normal conditions.

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