DS3800HCMB1C1B | GE Mark V Analog Output Module

Description

Product Introduction

The 1C suffix strikes a balance between the low-fusing 1A boards and the high-capacity 1E variants we’ve seen on the HCMA. The DS3800HCMB1C1B brings spring-cage push-in termination to the output side, with 1A fusing on the field supply rail—enough capacity to handle eight 20mA outputs (160mA total) with plenty of headroom for inrush from servo valves. If your plant has standardized on spring-cage for termination speed across all I/O, this board completes the set.

We’ve measured the voltage drop across the 1A fuse at 20mA load at under 0.2V, which preserves your compliance voltage for driving high-impedance loads. The spring-cage terminals we’ve already covered—quick termination, no torque spec, but watch the wire prep. One thing we’ve noticed on the output side specifically: if your actuator cables have high capacitance (long runs, shielded cable), the HCMB’s output can oscillate slightly when driving purely capacitive loads. The 1C suffix’s spring terminals don’t affect that—it’s a board-level design characteristic. We recommend adding a 100Ω series resistor in the loop if you experience oscillation. GE’s application note GEH-5838 covers this in detail.

Key Technical Specifications

Compatible Replacement Models

Frequently Asked Questions (FAQ)

Q: Can I drive a 4-20mA valve positioner with the HCMB1C1B?
A: Yes, if the positioner’s input impedance is under 500Ω. Most industrial positioners (Fisher, Masoneilan) are 250Ω or lower. At 20mA, the voltage drop across the load is 5V (250Ω) or less, leaving plenty of compliance voltage from your 24V supply. The 1A fuse is more than adequate—you’re drawing 20mA per channel, well below the 1A rating.

Q: The HCMB1C1B has spring-cage terminals. Do I need to use ferrules for stranded wire?
A: Yes—for the same reasons we gave on the HCMA variants. Stranded wire without a ferrule splays under the spring pressure, especially on outputs that drive actuators (which may have vibration feedback). Use ferrules, or use solid copper wire. We’ve seen output connections fail after 6 months on reciprocating compressors due to splayed strands. Ferrules solved the issue. The 1C terminals accept ferrules up to 2.5mm².

Q: Does the 1C suffix affect the output settling time or accuracy?
A: No. The suffix only changes termination and fusing. The analog output electronics are identical across all HCMB variants. The 1C1B’s 5ms settling time and 0.25% accuracy are the same as the 1A1B or 1E1G. So if you’re swapping suffixes, your control loops won’t see any difference in response.

Q: What’s the total current draw from the field supply if I’m driving all 8 outputs at 20mA?
A: 8 channels × 20mA = 160mA. That’s the signal current. The board itself draws negligible current from the 24V rail. Your power supply needs to deliver 160mA plus any internal losses. The 1A fuse is overkill for this scenario—you could run eight boards simultaneously (64 channels) and still be under 1.3A. The fuse protects the supply from a short circuit, not from typical operation.

Q: Can I use the HCMB1C1B for 0-10V outputs instead of 4-20mA?
A: Yes, per-channel jumper selection. The jumper position for voltage outputs is the same as on the HCMA—near each channel terminal. For voltage mode, the output drives 0-10V into a minimum 2kΩ load. If your actuator input impedance is lower, you won’t reach full 10V. Many older servo amplifiers have 1kΩ input—that will draw 10mA and may overheat the output driver if sustained. Use a buffer amplifier if needed. We’ve seen this issue on legacy Woodward actuators.

Q: The HCMB1C1B has 1A fuses, but I’ve seen variants with 2.5A. Should I upgrade to the 2.5A version?
A: Only if you’re experiencing fuse failures on inrush. The 1A fuse can handle brief surges—slow-blow fuses can ride through 2x overload for 100ms. If your actuators have huge inrush (some servo valves draw 50mA for 200ms on step changes), you might blow the 1A. We’ve measured inrush on some high-speed valves at 80mA—still under 1A. Unless you’re driving solenoids (which you shouldn’t be with this board), the 1A is fine. Stick with it.

Q: How do I verify the 1C1B’s output calibration in the field without a lab?
A: Command each channel to a known output—say 12mA (50% of span). Measure the current with a precision multimeter in series with the load. It should read 12.00mA ±0.03mA (0.25% of 16mA span). If you’re off by more than that, the board may need recalibration. But before you blame the board, verify your multimeter is accurate and that your load isn’t varying. We’ve seen field techs chase calibration errors only to find a fluctuating power supply. Measure the 24V supply first—it must be stable to within ±0.5V.

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