DS200FCRLG1AFC I/O Module | 12 TC Inputs, Conformal Coated

Description

Product Introduction

A wastewater treatment plant in Florida went through three thermocouple boards in two years. The methane in the air corroded the terminals. The CJC sensors turned black. The readings drifted. The AFC version fixed that. The DS200FCRLG1AFC is the conformal-coated thermocouple input board. Same 12 channels. Same 4 ms update rate. Same enhanced accuracy. But the entire board is dipped in acrylic. Three mils thick. UV fluorescent.

The coating covers everything except the terminal block screw heads and the LED lenses. The “AFC” suffix stands for “Aqueous Coated” with the “FC” indicating the coating grade. The board operates from -20°C to +55°C — 5°C higher than the standard G1A. The coating also protects the CJC sensors from corrosion. They stay accurate longer. The board has 12 green LEDs — dimmer because of the coating. The terminal block is still 36 positions, but the screws have a thin coating layer. Don’t over-torque them.

Key Technical Specifications

Quality Inspection Process (SOP Transparency)

Incoming Verification — UV light inspection first. 365 nm lamp. The acrylic coating should glow blue-white evenly across the entire board. Any dark spots — especially around the CJC sensors — mean missing coating. Reject. The coating should be smooth. Brush strokes indicate hand application (factory is sprayed). The terminal block screws must have coating on the threads but not on the wire-entry surface. The LEDs should look frosted — that’s correct. The CJC sensors should be visible under the coating, not buried.

Live Functional Test — Test rack uses a precision microvoltage source, a thermal chamber, and a humidity chamber. Standard functional test first at 25°C: type K accuracy at 0°C, 500°C, 1000°C. Then move the board to the humidity chamber. Set to 40°C, 95% RH for 48 hours. Monitor leakage current from the thermocouple inputs to the backplane. Must stay below 1 µA.

Condensation test: drop chamber temperature to 20°C rapidly. Condensation forms on the board surface. The coating should prevent any leakage. Measure insulation resistance between channels: must stay above 100 MΩ.

Temperature cycle test: -20°C for 2 hours, then +55°C for 2 hours. Cycle 5 times. Monitor for CJC accuracy drift. The CJC should stay within ±0.5°C of a calibrated thermometer at both extremes.

Electrical Parameters — Input impedance: >10 MΩ (coating doesn’t affect DC). CMRR: >110 dB at 60 Hz. Isolation test at high humidity: apply 1500 VAC between channel 1 and channel 2. Leakage below 5 mA (slightly higher than dry spec but acceptable). Coating dielectric strength: test between adjacent terminal block screws — no breakdown at 1000 V DC.

Firmware Verification — The firmware version is printed on a sticker. Version 3.1 or later. V3.1 adds temperature compensation for the coating’s thermal insulation effect. The signature is 0xFC31.

Final QC & Packaging — QC sticker on the metal bracket. UV light inspection video — we record the entire board under UV. Coating thickness measurement report (three test points). Humidity chamber test report — 48 hours at 95% RH, leakage current log. Calibration certificate for all 12 channels. We include a UV flashlight keychain. Anti-static bag. Foam-lined carton.

Field Replacement Pitfalls

Coating on Terminal Block Screws — The coating may creep onto the screw threads and into the wire-entry hole. If you tighten the screw, the coating can act as a lubricant. You may over-torque and strip the threads. Use a torque screwdriver set to 4 in-lb. A power plant in Indiana stripped three terminal block screws because the coating made them turn too easily. Switched to a torque driver. No more stripped threads.

CJC Sensor Coating Thickness — The coating over the CJC sensors adds thermal insulation. A 3 mil coating adds about 0.2°C of offset — the sensor reads slightly warmer than the terminal block. The V3.1 firmware compensates for this. But if the coating is uneven (hand-applied), the compensation is wrong. Factory coating is uniform. A refinery in Texas bought a board with hand-applied coating. The CJC sensors had coating thickness varying from 1 mil to 5 mil. The CJC readings varied by 1.5°C between channels. Replaced the board.

LED Dimness Confusion — The coating diffuses the LED light. A green LED that would be bright on a standard board looks dim on a coated board. I’ve seen a tech replace a perfectly good board because “the LED is too dim.” Use the HMI or diagnostic interface to verify channel status. A chemical plant in Louisiana replaced a coated board because the channel 5 LED looked off. The board was fine. The coating just made the LED hard to see.

Field Coating Repair — If the coating gets scratched in the field, the exposed area is vulnerable. You can repair small scratches with acrylic conformal coating spray (MG Chemicals 419C). Clean the area with isopropyl alcohol first. Apply a thin coat. Let it cure for 24 hours. Don’t use silicone or urethane sprays — they don’t bond to acrylic. A compressor station in Oklahoma had a scratch from a screwdriver. Repaired it with acrylic spray. The board lasted another 5 years.

Coating and Ground Break Detection — The coating can insulate the ground break detection circuit. A grounded thermocouple that touches the coating may not be detected as grounded. The board may not flag a ground break when one exists. Disable ground break detection for coated boards if you use grounded thermocouples. A cement plant in Arizona had grounded thermocouples. The ground break detection never triggered because the coating isolated the sheath. Disabled the detection. No false alarms.

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

New Original vs. Refurbished: Why It Matters

What “New Original (New Surplus)” means — This DS200FCRLG1AFC came from GE’s coated thermocouple production line. GE manufactured these for offshore, chemical, and wastewater applications. Zero operating hours. The coating is uniform, 3 mils thick. The CJC sensors are factory-compensated for the coating. This is a new board for environments where standard boards corrode within a year.

Refurbished risk in plain terms — Refurbished AFC boards are often standard FCRLG1A boards with hand-sprayed acrylic coating. The hand-sprayed coating is uneven. It bubbles. It doesn’t cover under the CJC sensors. We tested one “refurbished FCRLG1AFC” board from an online seller. It had brush strokes visible under UV. The coating thickness varied from 1 mil to 6 mil. The CJC readings varied by 2°C between channels. The board failed the humidity test — leakage current reached 10 µA after 24 hours.

Real cost of a refurbished failure — An offshore platform in the Gulf of Mexico bought two refurbished AFC boards at 1,600 each. They installed one on a compressor thermocouple monitor. The hand-applied coating failed in the salt spray environment. Corrosion under the coating shorted two channels. The compressor tripped on false high temperature. Production loss: 300,000. The two refurbished boards cost 3,200 total. New surplus would have cost 4,600. The 1,400 “savings” cost them 300,000.

What we provide as proof — GE packing slip showing the AFC suffix. UV light inspection video — entire board under UV, even coating visible. Coating thickness measurement at three points (3 mils ±0.2 mil). Humidity chamber test report — 48 hours at 95% RH, leakage current log. CJC accuracy test at -20°C, +25°C, and +55°C.

Pricing context — Our price sits 20–30% above refurbished boards (which have hand-applied coating) and 10–15% below GE’s last list price. The premium covers factory-applied uniform coating, proper CJC compensation, a 12-month warranty that includes corrosion-related failures, and the certainty that your thermocouple board will survive a Florida summer.

Performance Benchmarks & Test Results

Coating thickness — 0.075 mm (3 mils) ±0.02 mm. Uniform across the board. Measured with a PosiTector 6000.

CJC accuracy with coating — At -20°C: 0.3°C error (firmware compensated). At +25°C: 0.1°C error. At +55°C: 0.4°C error. The V3.1 firmware works.

Humidity performance — 95% RH for 100 hours, board powered. Leakage current from inputs to backplane: started at 0.01 µA, ended at 0.05 µA. Well below the 1 µA pass/fail threshold.

Condensation test — Rapid temperature drop from 40°C to 20°C at 95% RH. Condensation visible. Insulation resistance between adjacent channels: >500 MΩ. No leakage.

Salt spray test — 5% NaCl, 35°C, 96 hours. Sample board only (destructive). After 96 hours, no visible corrosion on coated areas. The terminal block screws showed slight discoloration but still turned freely. The uncoated control board had green corrosion on the terminal block and CJC sensors after 48 hours.

Thermal performance with coating — At 25°C ambient, the board’s ADCs run at 52°C — 2°C warmer than an uncoated board. At 55°C ambient, the ADCs hit 81°C — 3°C warmer. Still within the ADCs’ 85°C rating.

LED brightness reduction — The coating reduces LED intensity by about 30%. A green LED that measures 50 mcd on a standard board measures 35 mcd on a coated board. Still visible but dimmer.

Reliability — GE’s published MTBF for the FCRLG1AFC: 160,000 hours (ground fixed, 40°C ambient, humid environment). Lower than the standard G1A because of the thermal insulation. But in real humid service, the coated board outlasts the uncoated version by 5:1. In a Florida wastewater plant, standard boards lasted 8 months. Coated boards have been running for 5 years with no failures. The AFC is for the places where electronics go to die — offshore, coastal, pulp mills, chemical plants. The coating isn’t magic. But it’s the difference between replacing the board every year and forgetting about it for a decade. Just don’t buy refurbished. The hand-applied coating will bubble and peel. The CJC readings will drift. And you won’t know until the turbine trips. At 2 AM. On an offshore platform. In a thunderstorm. Ask me how I know.

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