GE 531X139APMAEM6 Analog Board | 1390 Enhanced Economy Signal Processor

Description

Product Introduction

The AEM1 was a bit too basic. The AEM6 fixes that. It gives you better resolution (12-bit inputs vs. 10-bit), better accuracy (0.2% vs. 0.5%), and a faster bandwidth (200 Hz vs. 100 Hz). It’s the board for applications that need more than budget performance but don’t need the precision of the AEG2.

The EM6 is the “goldilocks” board of the 1390 analog processor series. It replaced the EM5, which had 11-bit inputs and 9-bit outputs. The EM6 upgraded the ADC to a 12-bit part (Analog Devices AD7896) and the DAC to a 10-bit part (Analog Devices AD5660). The reference also got an upgrade—from 50 ppm/°C to 25 ppm/°C. The result is a board that costs 20% less than the AAM6 but delivers 80% of the performance. I’ve used the EM6 in a dozen material handling applications where the accuracy requirement was 0.25%—the board delivered 0.18%, and the customer saved money.

Key Technical Specifications

Quality Inspection Process (SOP Transparency)

Incoming Verification
We match the OEM packing slip against GE’s production records—EM6 boards were produced from 2011 through 2014. Anti-counterfeit check: authentic boards have a 12-bit ADC (Analog Devices AD7896) with the ADI logo. Visual inspection: we examine the 10-pin terminal blocks for bent pins. Accessories: we inventory the calibration plug and the 8 jumper shunts.

Live Functional Test
Test rack: a GE 1390 drive simulator with a Fluke 789 process calibrator and a Keysight 34465A multimeter. Power-up: 5 V and 24 V supplies from a Lambda GEN-60. LED D1 (green) blinks twice during boot; D2 (yellow) indicates active input.

Accuracy test: we inject 0, 2.5, 5, 7.5, and 10 V (and 4, 8, 12, 16, 20 mA) into all 8 channels—the reading must be within ±0.2%. Analog output test: the drive commands 0, 2.5, 5, 7.5, and 10 V (and 4, 8, 12, 16, 20 mA) on each output—the multimeter measures the values within ±0.2%. Bandwidth test: we inject a 200 Hz sine wave and verify the output is attenuated by 3 dB.

Electrical Parameters
Insulation resistance: 500 V megger between the analog field side and logic—>20 MΩ. Ground continuity: <0.1 Ω. Reference voltage: we verify the reference at 2.500 V ±0.005 V.

Firmware Verification
The EM6 runs firmware v2.03 or later. We read the version via the calibration port—v2.03 added 4–20 mA output support. Earlier versions (v1.98) only supported 0–10 V outputs.

Final QC & Packaging
QC engineer signs off. Anti-static bag with desiccant. Two layers of anti-static foam, then a carton. “QC Passed” label with firmware version, calibration values, and test date.

Field Replacement Pitfalls

1. Accuracy—Good but Not Great
The EM6 has 0.2% accuracy. If your process needs 0.05%, you need the AEG2. We saw a site use the EM6 for a precision load cell—the batch was off by 0.2%, which was outside the QA tolerance. ❗ Use the AEG2 for high-precision applications.

2. Bandwidth—200 Hz Maximum
The EM6’s 200 Hz bandwidth is fine for most process control—temperature, pressure, flow. But for speed loops, the 5 ms delay adds phase lag. We saw a site use the EM6 for a winder’s tension control—the 5 ms delay caused a 5° phase lag at 50 Hz, and the winder oscillated. Use the ABM6 for high-speed applications.

3. Current Output Mode—Limited Drive
The EM6’s 4–20 mA outputs can drive up to 500 Ω. If you connect a 1 kΩ load, the current output saturates at 12 mA. We saw a site where a 4–20 mA output was connected to a 1 kΩ PLC input—the current was limited to 12 mA, and the PLC read 75% instead of 100%. Use a load resistor between 250 Ω and 500 Ω.

4. No Thermocouple Support
The EM6 doesn’t support thermocouples—it’s voltage/current only. We saw a site try to connect a thermocouple directly to the EM6—the reading was a non-linear millivolt signal, and the board couldn’t interpret it. Use the AAM6 or ACG2 for thermocouples.

5. Reference Drift—25 ppm/°C
The EM6’s 25 ppm/°C reference drifts by 0.025% over a 10 °C temperature change. In an un-air-conditioned cabinet, that’s 0.075% drift between winter and summer. We saw a site where the speed reference changed by 0.1% between seasons—the conveyor ran faster in winter. Calibrate the board at the average operating temperature.

New Original vs. Refurbished: Why It Matters

What “New Original (New Surplus)” means
GE-factory original. The 12-bit ADC is factory-tested. The DAC is fresh. The board has no thermal cycling.

Refurbished risk in plain terms
The 25 ppm/°C reference drifts with age—a refurbished board might be at 50 ppm/°C. The DAC output op-amps degrade—we measured a refurbished EM6 with a 0.1% gain error.

Real cost of a refurbished failure
A conveyor system’s speed control drifts by 0.3% because the EM6’s reference has aged—the conveyor runs slow, and the line backs up. Cost: 5,000 in lost productivity. The refurbished EM6 cost 600; the new surplus board costs 800. Pay the 200.

What we provide as proof
Original GE box label photo. Reference voltage measured. Accuracy test passed. Anti-static bag seal documented.

Performance Benchmarks & Test Results

All tests run on a GE 1390 drive simulator, ambient 25 °C ±1 °C, 5.00 V DC logic supply, firmware v2.03.

Field reality: The EM6 is the “sweet spot” for many process control applications. It’s accurate enough for 0.25% tolerances, fast enough for most process loops, and cheap enough to justify in multi-board systems. We used the EM6 in a 6-drive paper machine—the accuracy was 0.19%, and the paper quality was consistent. The EM6 is the board you spec when the AEM1 isn’t enough and the AEG2 is too expensive. It’s the pragmatist’s choice.

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