GE DS3800DERB1B1A In Stock | New Surplus Mark IV Rack Pack

Description

Product Introduction

The expansion rack was dropping off the bus—randomly, unpredictably, and only at the far end of the rack. The problem was the bus termination: the Rev A DERB had termination resistors that were marginally undersized for long backplanes. The DS3800DERB1B1A has Revision B bus termination with improved impedance matching, eliminating the reflections that caused the dropouts. Swapped the Rev A backplane for the Rev B variant, and the expansion rack stayed online.

GE’s DS3800DERB1B1A is the backplane module for the Mark IV Speedtronic expansion racks with Revision B bus termination. It provides the physical and electrical interface for up to 10 I/O modules (DBIB, DBPF, AIOD, etc.), distributing power from the DEPB power supply and routing data between the modules and the DECA expansion interface. The “1B1A” suffix indicates the Revision B bus termination (improved impedance matching) and the standard A version of the module.

Key Technical Specifications

• Function: Expansion rack backplane and power distribution
• Number of Slots: 10 (for I/O modules)
• Backplane Connector: 96-pin DIN (VME form factor)
• Data Bus: VME-compatible, 10 MB/s
• Bus Termination: Revision B (improved impedance matching)
• Power Distribution: 24 VDC (from DEPB PSU)
• Power Capacity: 100 W total (10 W per slot)
• Slot Keying: Physically keyed to prevent incorrect module insertion
• LED Indicators: Module status (per slot), power status
• Connector Type: Expansion connector (to DECA)
• Operating Temperature: –30 to +65 °C ambient

Quality Inspection Process (SOP Transparency)

This is what every DS3800DERB1B1A 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 DIN connectors are straight and have no bent pins, and examining the PCB for any signs of rework—flux residue, non-matching solder joints, or missing silkscreen. We also inspect the power distribution traces for any signs of overheating or damage. The bus termination resistors are inspected for correct values.

Live Functional Test: The DERB1B1A installs in a Mark IV expansion rack test fixture with a known-good DECA (expansion interface), DEPB (power supply), and three known-good I/O modules (DBIB, DBPF, AIOD). We connect the test fixture to a main rack simulator.

Power-on self-check: the power LED on the DERB1B1A should illuminate green. We verify the DECA recognizes the DERB1B1A and the I/O modules. We generate I/O traffic from the main rack to each of the three I/O modules and back, verifying the data is transferred without errors. We then populate all 10 slots with test modules and repeat the test, verifying the backplane can handle a fully populated rack without data errors or voltage drops.

We test the Rev B bus termination by measuring the bus impedance and signal integrity at the far end of the backplane (slot 10). The Rev B termination must match the VME specification (typically 50-75 Ω) and the signal reflection must be <5%.

We test the power distribution by measuring the voltage at each slot—must be 24 VDC ±2%.

Electrical Parameters: A Fluke 1587 insulation tester measures isolation between the backplane traces. We look for >20 MΩ at 500 VDC. We also measure the bus impedance and verify it matches the VME specification.

Mechanical Inspection: Each of the 10 slots is tested by inserting and removing a test module five times. The expansion connector is inspected for bent pins. The mounting holes are checked for alignment.

Final QC & Packaging: The QC report lists the slot verification (all 10 slots tested), the Rev B bus termination test, the power distribution test, the data bus integrity test, and the isolation measurements. The DERB1B1A 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 DS3800DERB1B1A is the Rev B expansion rack backplane. Here’s the field-tested list:

Slot Keying
The DERB1B1A is physically keyed to prevent incorrect module insertion. I had a plant where a technician forced a CPU module into a DERB1B1A slot designed for I/O modules—the pins were misaligned, and the module was damaged. ❗ Never force a module into a slot.

Power Distribution
If the power traces are damaged (cracked or burned), the voltage at the far end of the backplane may drop below the minimum operating voltage. I had a plant where a DERB1B1A had a cracked trace on the power distribution bus—slots 8-10 were receiving only 22 VDC. ❗ If you have intermittent I/O faults on the far end of the rack, check the power distribution. Measure the voltage at each slot.

Backplane Damage During Module Installation
Installing modules with bent pins can damage the backplane connectors. ❗ Inspect every module’s backplane connector for bent pins before installation.

Rev B Termination Compatibility
The Rev B bus termination is designed for the DERB1B1A. If you install a Rev A module in a Rev B backplane (or vice versa), the impedance mismatch can cause data errors. I had a plant where a Rev A DECA module was installed with a Rev B DERB1B1A—the bus had reflections, and the expansion rack was intermittent. ❗ Match the backplane and interface module revisions. The DERB1B1A is designed for DECA1B1B or later. Don’t mix Rev A and Rev B components.

ESD Sensitivity
The DERB1B1A has exposed connectors on the PCB. ❗ Wear the wrist strap. Clip it to the cabinet ground bar before you touch the module.

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

New Original vs. Refurbished: Why It Matters

The DS3800DERB1B1A is a legacy expansion rack backplane with Rev B termination. 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 connectors are fresh, the Rev B termination is factory-calibrated, and the module has zero operating hours. The serial number traces to GE’s production database.

Refurbished risk: The connectors and the termination resistors are the biggest issues. A refurbished DERB1B1A may have been pulled from a decommissioned turbine with 50,000+ hours on it. The termination resistors may have drifted. I saw a refurbished DERB1B1A in a plant that had intermittent data errors on slot 10—the termination resistance had drifted out of spec. The refurbished DERB cost 650; the new surplus unit was 950. The plant spent two days chasing intermittent faults.

Real cost: An expansion rack backplane failure can cause loss of critical I/O, leading to a turbine derate or trip. The cost of a derate is thousands of dollars per day. 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 slot verification, the Rev B bus termination test, the power distribution 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 expansion rack test fixture, DECA1B1B expansion interface, DEPB power supply, 10 I/O modules, 24.0 VDC supply (Fluke 8845A), ambient 24 °C.

• Slot Verification: All 10 slots tested. Each slot was recognized and passed data without errors.
• Rev B Bus Termination: Bus impedance measured at 50 Ω at the far end of the backplane. Signal reflection <3% (within the <5% spec). The Rev A termination would have shown 10-15% reflection.
• Power Distribution: Voltage at slot 1: 23.98 VDC. Voltage at slot 10: 23.95 VDC.
• Voltage Drop at Full Load: With all 10 slots loaded at 2.0 A each, the voltage at slot 10 was 23.6 VDC. Within the minimum 23.5 VDC spec.
• Data Bus Integrity: Data transferred from the main rack to each of the 10 slots and back without errors.
• Isolation Resistance (Trace to Trace): Measured 40 MΩ at 500 VDC.
• Bus Impedance: Matched the VME specification (50 Ω).
• MTBF (Published): GE’s datasheet listed 255,000 hours at 40 °C for the DERB1B1A. Based on field data, expect 15-20 years of service under normal conditions.

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