GE DS3800DISA In Stock | New Surplus Mark IV I/O Pack

Description

Product Introduction

The turbine was tripping—randomly, unpredictably, and only during high-speed events. The problem was the I/O scan rate: the old scanner was too slow to catch the transient. The DS3800DISA is the high-speed discrete I/O scanner that captures fast-changing signals. Swapped the old scanner for the DISA, and the turbine stayed online.

GE’s DS3800DISA is the discrete I/O scanner module for the Mark IV Speedtronic turbine control system. It provides high-speed scanning of up to 64 discrete I/O channels, with a 1 ms scan rate that captures fast-changing signals for critical protection and control functions. The module has optoisolation on every channel, a 37-pin D-sub connector for field wiring, and a 96-pin DIN backplane connector.

Key Technical Specifications

• Channel Count: 64 discrete I/O channels
• Scan Rate: 1 ms per scan
• Input Types: 24 VDC (18-36 V range)
• Output Types: 24 VDC, 0.5 A per channel
• Optoisolation: 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 DS3800DISA 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 to all 64 input channels and verify the module reads the correct states. We command all 64 output channels and verify the correct states.

We test the scan rate by applying a fast-changing signal (1 kHz) and verifying the module captures the state changes correctly (the 1 ms scan rate must capture the signal). We measure the scan rate with an oscilloscope.

Electrical Parameters: A Fluke 1587 insulation tester measures isolation between the I/O channels and the backplane. We look for >20 MΩ at 500 VDC. We also measure the output voltage drop at 0.5 A—must be <0.5 V.

Mechanical Inspection: The VME connector is inspected for bent pins. The D-sub connector is inspected for bent pins. The mounting holes are checked for alignment.

Final QC & Packaging: The QC report lists the channel verification, the scan rate test, the output voltage drop test, and the isolation measurements. 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 DS3800DISA is the high-speed I/O scanner. Here’s the field-tested list:

Scan Rate Configuration
The DISA’s 1 ms scan rate is fixed, but the system must be configured to use the high-speed scanning. If the configuration is wrong, the module will scan at the default (slower) rate. I had a plant where a DISA was installed but the system was configured for the slower scanner—the high-speed scanning wasn’t working. ❗ The system must be configured to use the DISA’s high-speed scan rate. Check the configuration in ToolboxST.

Wiring Identification
The DISA’s 64 I/O channels are on multiple connectors. If a wire is mislabeled, you’ll wire it incorrectly. ❗ Label every wire before you remove it. Use numbered ferrule markers.

Output Overload
The DISA’s outputs are rated for 0.5 A. If you exceed that, the output driver may fail. I had a plant where a 1 A solenoid was connected to a DISA output—the driver failed. ❗ The outputs are 0.5 A maximum. Use an interposing relay for higher loads.

D-Sub Connector Damage
The DISA 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.

Firmware Compatibility
The DISA has its own firmware. If the firmware is mismatched with the CPU firmware, the scan rate may not be correct. ❗ Check the firmware version of the old module before ordering a replacement. Match it exactly.

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

New Original vs. Refurbished: Why It Matters

The DS3800DISA is a legacy high-speed I/O scanner. Refurbishment risk is significant.

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 high-speed scanning logic is fresh, and the module has zero operating hours. The serial number traces to GE’s production database.

Refurbished risk: The high-speed scanning logic and output drivers are the biggest issues. A refurbished DISA may have been pulled from a decommissioned turbine with 50,000+ hours on it. I saw a refurbished DISA in a plant that had intermittent scan errors—the high-speed logic had failed. The refurbished module cost 900; the new surplus unit was 1,200. The plant chased random trips for two weeks.

Real cost: A failed high-speed scanner can cause a turbine to trip on fast transients. The cost of a trip is tens of thousands of dollars. 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 scan rate 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 64 channels, 24.0 VDC supply (Fluke 8845A), ambient 24 °C.

• Scan Rate: 1.02 ms measured. Within the 1 ms spec.
• Input Response Time: 1.05 ms from input edge to network update.
• Output Response Time: 1.0 ms from network write to output pin.
• Output Voltage Drop: At 0.5 A, voltage drop = 0.35 V. Within the <0.5 V spec.
• 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 190,000 hours at 40 °C for the DISA. Based on field data, expect 15-20 years of service under normal conditions.

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