GE DS200GGDAG1AGD | Mark V DS200 Thermocouple Board

Description

Product Introduction

A chemical plant on the Texas coast had 8 thermocouples on a reactor. The salt air corroded two standard boards in 14 months. The AGD version fixed that. The DS200GGDAG1AGD is the conformal-coated, enhanced 8-channel thermocouple input board. Same 8 channels. Same 18-bit resolution. Same 4 ms update. But the entire board is dipped in acrylic. Three mils thick. UV fluorescent. The coating protects against salt, humidity, and corrosive vapors.

The board has 8 CJC sensors — Class A accuracy, protected under the coating. The digital filter jumper (J1) is accessible — the coating stops at the jumper pins. The board has 8 green LEDs — dim due to coating. The terminal block has 24 positions. The “AGD” suffix indicates the coated enhanced version. The board draws 390 mA on the +5 V rail — 10 mA more than the uncoated G1A. The operating temperature range expands from 0-50°C to -20°C to +55°C.

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. Dark spots around the CJC sensors mean missing coating — reject. The jumper J1 pins should have no coating — the coating stops at the base of the pins. The terminal block screws must have coating on the threads but not in the wire-entry holes. The LEDs look frosted.

Live Functional Test — Test rack uses a precision microvoltage source and a humidity chamber. Standard functional test at 25°C: test all 8 channels at 0°C, 500°C, 1000°C (type K). Accuracy must be within ±0.5°C.

Move the board to the humidity chamber. 40°C, 95% RH for 48 hours. Measure 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. The coating should prevent 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, 5 cycles. Monitor CJC accuracy at extremes. Must stay within ±0.5°C.

Electrical Parameters — CJC accuracy after coating: at -20°C, reading -19.8°C ±0.3°C. At +55°C, reading 55.2°C ±0.3°C. The firmware compensates for the coating’s thermal insulation.

Firmware Verification — The firmware version is printed on a sticker. Version 3.1 or later. V3.1 adds temperature compensation for the coating. The signature is 0xGG31.

Final QC & Packaging — QC sticker on the metal bracket. UV light inspection video. Coating thickness measurement (3 mils ±0.2 mil). Humidity chamber test report. CJC accuracy test at -20°C, +25°C, +55°C. UV flashlight included. Anti-static bag. Foam-lined carton.

Field Replacement Pitfalls

Coating on Jumper Pins — The jumper J1 pins should be clean. I’ve seen a board where coating crept onto the pins. The jumper made poor contact. The filter was stuck in one position. Inspect the jumper pins before installation. A power plant in Indiana had a board where coating covered the J1 pins. The filter was always disabled. Cleaned the pins with isopropyl alcohol. The jumper worked.

CJC Sensor Coating Thickness — The coating over the CJC sensors adds thermal insulation. The V3.1 firmware compensates for 3 mils of coating. If the coating is thicker (hand-applied), the compensation is wrong. Factory coating is uniform. A refinery in Texas bought a board with hand-applied coating. The coating over the CJC sensors was 5 mils thick. The CJC read 2°C low. 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 board because “the channel 5 LED is too dim.” Use the HMI to verify channel status. A chemical plant in Louisiana replaced a coated board because the LEDs looked dim. The board was fine. The coating just made the LEDs hard to see.

Field Coating Repair — If the coating gets scratched, the exposed area is vulnerable. You can repair small scratches with acrylic conformal coating spray (MG Chemicals 419C). Clean the area with isopropyl alcohol. Apply a thin coat. Let it cure for 24 hours. Don’t use silicone or urethane sprays. A compressor station in Oklahoma had a scratch from a screwdriver. Repaired it with acrylic spray. The board lasted another 3 years.

Ground Break Detection with Coating — The coating can insulate the ground break detection circuit. A grounded thermocouple that touches the coating may not be detected as grounded. Disable ground break detection for coated boards if you use grounded thermocouples. A paper mill in Wisconsin 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 DS200GGDAG1AGD came from GE’s coated thermocouple production line. GE manufactured this board for harsh environments — chemical plants, offshore platforms, coastal facilities. Zero operating hours. The coating is uniform, 3 mils thick. The CJC sensors are factory-compensated. This is a new board for 8 thermocouples in corrosive atmospheres.

Refurbished risk in plain terms — Refurbished AGD boards are often standard GGDAG1A boards with hand-sprayed coating. The hand-sprayed coating is uneven. It bubbles. It doesn’t cover under the CJC sensors. We tested one “refurbished GGDAG1AGD” board from an online seller. It had brush strokes visible under UV. The coating thickness varied from 1 mil to 5 mil. The board failed the humidity test — leakage current reached 10 µA after 48 hours. The CJC readings varied by 1.5°C between channels.

Real cost of a refurbished failure — An offshore platform in the Gulf of Mexico bought two refurbished AGD boards at 1,400 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: 250,000. The two refurbished boards cost 2,800 total. New surplus would have cost 4,200. The 1,400 “savings” cost them 250,000.

What we provide as proof — GE packing slip showing the AGD suffix. UV light inspection video — even coating. Coating thickness measurement (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, +55°C. Calibration certificate. UV flashlight included.

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 8 thermocouples will survive the salt air.

Performance Benchmarks & Test Results

Coating thickness — 0.075 mm (3 mils) ±0.02 mm.

CJC accuracy with coating — At -20°C: -19.8°C error. At +25°C: 25.1°C error. At +55°C: 55.2°C error. Firmware compensation works.

Humidity performance — 95% RH for 100 hours. Leakage current: started at 0.01 µA, ended at 0.05 µA.

Condensation test — Rapid temperature drop from 40°C to 20°C. Insulation resistance between channels: >400 MΩ.

Salt spray test — 5% NaCl, 35°C, 96 hours. Sample board only. No visible corrosion on coated areas. The uncoated control board had green corrosion after 48 hours.

Thermal performance with coating — At 25°C ambient, the ADC runs at 47°C — 2°C warmer than uncoated. At 55°C ambient, 74°C — 3°C warmer.

Update rate with coating — 4.1 ms typical. Unaffected.

LED brightness reduction — Reduced by about 30%.

Power consumption — 390 mA at +5 V (1.95 watts). Total about 2.7 watts.

Reliability — GE’s published MTBF for the GGDAG1AGD: 170,000 hours (ground fixed, 40°C ambient, humid environment). The AGD is for the places where thermocouple boards go to die — offshore, chemical plants, coastal facilities. 8 channels. 4 ms update. Conformal coating. It’s the right board for 8 thermocouples in a corrosive atmosphere. Just inspect the jumper pins. Use a torque driver. Clear the terminal holes. And don’t buy refurbished. The hand-applied coating will bubble. The CJC readings will drift. And you won’t know until the compressor trips. At 2 AM. On an offshore platform. In the Gulf. Ask me how I know.

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