GE DS3800DISA1A1B In Stock | New Surplus Mark IV I/O Pack

Description

Product Core Brief

• Model: DS3800DISA1A1B
• Brand: GE (General Electric)
• Series: Mark IV Speedtronic Turbine Control System
• Core Function: Provides fused high-speed discrete I/O scanning with Revision B scanning firmware for the Mark IV Speedtronic system.
• Type: I/O Scanner Module
• Key Specs: 64 discrete I/O channels; 1 ms scan rate; fused outputs; Rev B scanning firmware; 24 VDC; optoisolated; 37-pin D-sub connector; 96-pin DIN backplane.
• Condition: New Original (New Surplus) — not refurbished.

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
• Output Fusing: 0.5 A fast-acting, per output (field-replaceable)
• Fuse-Blown Indicator: Red LED per output
• Firmware: Revision B (improved scanning stability, enhanced fault detection)
• 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), fuse blown (red)
• Operating Temperature: –30 to +65 °C ambient

Quality Inspection Process (SOP Transparency)

This is what every DS3800DISA1A1B 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. The fuses are inspected—they must be 0.5 A fast-acting, properly seated.

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 Rev B scanning firmware by running the scanner at high speed with a heavy I/O load and verifying the scanning remains stable (no jitter or missed scans). We test the scan rate with an oscilloscope.

For the fuse test, we short-circuit each output and verify the 0.5 A fuse blows within 1 second. The red LED for that output must illuminate. We then replace the fuse and verify the output returns to normal operation.

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 fuse holders are tested.

Final QC & Packaging: The QC report lists the channel verification, the Rev B scanning stability test, the fuse 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 DS3800DISA1A1B is the fused high-speed I/O scanner with Rev B firmware. Here’s the field-tested list:

Fuse Rating and Substitution
The DISA1A1B uses 0.5 A fast-acting fuses. If you replace a blown fuse with a 1 A fuse, the output driver won’t be protected. ❗ Use the correct fuse: 0.5 A fast-acting. The fuse spec is printed on the module label.

Fuse-Blown LED Interpretation
The red LED illuminates when the fuse is open. But it draws its power from the output rail. If the rail is off, the LED won’t illuminate. ❗ The fuse-blown LED only works when the rail is powered.

Scan Rate Configuration
The DISA1A1B’s 1 ms scan rate is fixed, but the system must be configured to use the high-speed scanning. ❗ The system must be configured to use the DISA1A1B’s high-speed scan rate.

Rev B Firmware Compatibility
The Rev B scanning firmware requires CPU firmware v3.0 or later. I had a plant where a DISA1A1B was installed with a CPU running older firmware—the scanning was unstable. ❗ The Rev B DISA1A1B requires CPU firmware v3.0 or later. Check your CPU’s firmware version.

Output Overload
The DISA1A1B’s outputs are rated for 0.5 A, protected by a 0.5 A fuse. A 0.6 A overload may not blow the fuse but will overheat the driver. ❗ The outputs are 0.5 A maximum. Use an interposing relay for higher loads.

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

New Original vs. Refurbished: Why It Matters

The DS3800DISA1A1B is a legacy high-speed I/O scanner with fusing and Rev B firmware. Refurbishment risk is significant.

New Original (New Surplus) means this unit came from GE’s production line, sealed in an ESD-safe bag. The high-speed scanning logic is fresh, the Rev B firmware is genuine, the fuses are fresh, and the module has zero operating hours. The serial number traces to GE’s production database.

Refurbished risk: The Rev B firmware and high-speed scanning logic are the biggest issues. A refurbished DISA1A1B may have been pulled from a decommissioned turbine with 50,000+ hours on it. I saw a refurbished DISA1A1B in a plant that had intermittent scan errors—the high-speed logic had failed. The refurbished module cost 950; the new surplus unit was 1,250. 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 Rev B scanning stability test, the fuse 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 (firmware v3.0), test signals applied to all 64 channels, 24.0 VDC supply (Fluke 8845A), ambient 24 °C.

• Fuse Voltage Drop: At 0.5 A: 0.05 V.
• Fuse Blow Time: With a 0.75 A overcurrent, the fuse blew in 800 ms.
• Scan Rate: 1.02 ms measured. Within the 1 ms spec.
• Rev B Scanning Stability Test: Stable scanning with no jitter or missed scans under heavy I/O load.
• 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.
• 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 195,000 hours at 40 °C for the DISA1A1B. Based on field data, expect 15-20 years of service under normal conditions.

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