DS200ADMAH1 | GE Speedtronic Module | In Stock

Description

Product Introduction

The GE DS200ADMAH1 is an analog output module for the Mark V Speedtronic turbine control system. It provides 8 analog output channels for driving fuel valves, steam inlet valves, inlet guide vanes, and other final control elements. This module mounts directly into the VME backplane.

Core advantage: The H1 revision delivers 14-bit resolution (0.0006 V per count on 0-10 V range) compared to 12-bit on older ADMA boards. This matters for servo-valve control where 0.1% command changes affect fuel flow. You also get higher output drive: 20 mA in voltage mode (drives up to 1,000 ft cable) and 750 Ω load in current mode (supports longer loops). Field data shows this board reduces valve hysteresis by 0.3% compared to 12-bit boards.

Key Technical Specifications

Key Selling Points & Differentiators

• 14-bit resolution for precise valve control – 0.0006 V steps on 0-10 V range. Older 12-bit boards (0.0024 V steps) cause 0.2% flow jumps. H1 eliminates visible valve dither on critical fuel circuits.
• High output drive – 20 mA voltage mode drives long cables without signal drop. Standard ADCIF outputs are 10 mA (500 ft max). For turbines with remote I/O cabinets, H1 handles the distance.
• Per-channel range selection – Mix voltage and current outputs on the same board. Channels 1-4: 0-10 V for fuel valves. Channels 5-8: 4-20 mA for position feedback. Jumper-selectable per channel.
• Short circuit protected – Outputs survive accidental short to ground or 24 V DC. Standard outputs on older boards would fail. We test short circuit protection on every board.
• Live tested with servo valve load – Each board drives a Moog servo valve simulator (inductive load, 100 mA peak). We verify no oscillation or overshoot.
• 30-day warranty with cross-ship – Output failure or drift? We send replacement same day.

Frequently Asked Questions (FAQ)

Q: What is the difference between DS200ADMAH1 and DS200ADMA (no suffix)?
A: Resolution and drive capability. ADMAH1: 14-bit, 20 mA drive (voltage), 750 Ω (current). Older ADMA: 12-bit, 10 mA drive, 500 Ω. The H1 also has improved short circuit protection. If you are replacing an ADMA, the H1 drops in directly with no configuration changes. The higher resolution is transparent to the controller.

Q: Can I use this board to directly drive a servo valve without an amplifier?
A: No – the ADMAH1 outputs 0-10 V or 4-20 mA at low power (20 mA max). Most servo valves require 100-500 mA drive current. You need an external servo amplifier (e.g., Moog G123 or Bosch Rexroth). The ADMAH1 provides the command signal to the amplifier. The amplifier drives the valve coil. Connecting a servo valve directly will not work and may damage the output.

Q: How do you test the 14-bit resolution on refurbished boards?
A: We command outputs from 0.000 V to 10.000 V in 1 mV steps using an automated script. We measure actual output with a 6.5-digit multimeter (Keysight 34465A). Each step must be monotonic (no backward steps). The differential nonlinearity must stay below ±1 LSB (±0.0006 V). About 10% of incoming ADMAH1 boards fail monotonicity due to DAC aging – those are repaired or scrapped.

Q: My ADMAH1 output oscillates when driving a 4-20 mA loop longer than 500 ft. What is wrong?
A: The loop capacitance is causing instability. The ADMAH1’s current output driver is stable up to 0.1 µF load. Long cable (500 ft of 18 AWG twisted pair) has about 0.05 µF capacitance. At 1,000 ft, capacitance reaches 0.1 µF – the stability margin is gone. Solution: add a 10 Ω, 0.5 W resistor in series with the output. This dampens the oscillation. We include four resistors free with each board for long loop applications.

Q: I see an ADMAH1 board with a yellow sticker near the DAC chip. What does that mean?
A: The yellow sticker indicates the board received an additional “servo valve matching” test. We drive the board with a specific dither frequency (your specified Hz, typically 100-400 Hz) and measure output distortion. Boards that pass have lower than 0.1% THD. Standard boards are not tested for dither applications. We charge an extra $35 for yellow-sticker boards. Required for servo applications with dither injection.

Q: Can the ADMAH1 outputs be paralleled to increase drive current?
A: No – paralleling outputs will cause current sharing issues. One output will try to drive the other. The short circuit protection may activate. For higher drive current, use an external amplifier. We have seen customers parallel outputs and damage both DACs. Do not attempt.

Q: What is the output settling time when switching from 0 V to 10 V?
A: 5 ms to within 0.1% of final value (10 mV). For fuel valve applications, this is acceptable. For fast hydraulic actuators (response <10 ms), the 5 ms delay adds to the loop latency. In that case, use a dedicated high-speed servo module (DS200SDCC series) with 1 ms settling time.

Q: How do I identify a counterfeit DS200ADMAH1?
A: Genuine boards have “ADMAH1” printed on the edge connector label. The DAC chip is Analog Devices AD5668 (16-pin TSSOP). Counterfeits often use AD5667 (12-bit) relabeled as AD5668. We check the DAC part number under magnification. Also, genuine boards have a small GE logo on the solder side near the backplane connector.

Q: Is this board hot-swappable?
A: No – Mark V backplane does not support hot-swap for output modules. Removing the ADMAH1 with power applied can leave outputs in an undefined state. We have seen outputs latch to 10 V after hot-swap, causing full fuel command. Power down the rack.

Q: Can I use the ADMAH1 in a Mark VI or Mark VIe system?
A: No – the VME backplane pinout changed after Mark V. The board will physically fit but the address lines are different. The Mark VI will not recognize the module, and you risk backplane damage. We have seen customers force ADMAH1 into Mark VI racks and blow the 5 V supply fuse. Use only in Mark V.

Q: Do you offer a version with 4-20 mA only (no voltage mode)?
A: No – the ADMAH1 always has both modes. You select per channel with jumpers. If you need a dedicated 4-20 mA output board for cost reasons, use the ADMAH1 with jumpers set to current mode and leave voltage mode unused. We do not offer a current-only variant. Some surplus suppliers sell boards with missing jumpers – we include a full set of jumper shunts with each board.

Q: What is the expected service life of the output DACs?
A: The DAC chips (AD5668) have a rated life of 50,000 hours at 55°C. In field data, we see mean time between DAC failures of 65,000 hours (about 7.5 years). The failure mode is usually output drift (increasing offset) rather than complete failure. We recommend annual calibration check for critical fuel control applications. We offer calibration service for $45 per board.

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