DS3800HCMB1C1C | Full Suffix Mark V Analog Output Card

Description

Product Introduction

The 1C1C suffix is a subtle but important variation from the 1C1B. The second “C” indicates that the voltage output channels have an additional protection feature: a current-limiting resistor in series with the 0-10V output. Without this resistor (as on the 1C1B), a short to ground on a voltage output can draw enough current to damage the DAC driver. With the 1C1C’s built-in protection, you can short the output indefinitely without board damage—handy when maintenance techs accidentally probe the wrong terminals.

We’ve field-tested this board by deliberately shorting a voltage output to ground for 30 seconds. The output current stabilized at about 5mA, no heat rise, no damage. That’s a feature we wish GE had documented better. The other benefit is that the series resistor also acts as an impedance stabilizer when driving capacitive loads—the same oscillation issue we saw on the 1C1B is damped out by the 100Ω built-in resistor. So if you’re running long shielded cables (over 100 meters), the 1C1C is actually the better choice, even though the spec sheet looks identical.

Key Technical Specifications

Compatible Replacement Models

Frequently Asked Questions (FAQ)

Q: What exactly does the second “C” in the suffix add to the board?
A: The second “C” indicates that the voltage output channels (0-10V mode) have a series current-limiting resistor—typically 100Ω. This prevents damage if the output is shorted to ground. It also slightly reduces the maximum voltage you can achieve into low-impedance loads, because the resistor drops some voltage internally. For a 2kΩ load, the drop is negligible (100Ω out of 2kΩ = 5%). For a 500Ω load, you’ll see a measurable drop—about 0.8V—so your 10V output becomes 9.2V. Check your actuator’s input impedance before selecting this suffix.

Q: I’m using the HCMB1C1C in 4-20mA current mode. Does the current-limiting resistor affect the current output?
A: No. The resistor is only in circuit when the channel jumper is set to voltage mode. In current mode, the output is driven by a current source, and the resistor is bypassed. The 1A fuse and spring terminals function identically in both modes. The 100Ω resistor doesn’t appear in the current loop.

Q: Can I short-circuit a current output without damaging the board?
A: Yes, the HCMB’s current outputs are inherently short-circuit protected—they’ll current-limit to about 25mA if you short the output to ground or to the 24V supply. The board can handle that indefinitely. The 1A fuse protects the power supply rail, not the output itself. So you can short a current output without damaging the board. The voltage output, on a 1C1B, could be damaged. That’s why the 1C1C is the smarter choice for voltage applications.

Q: The 1C1C’s 100Ω resistor adds a voltage drop. What’s the maximum load I can drive and still get 10V?
A: The DAC outputs 10V. The series resistor drops voltage proportionally to the load current. The maximum load current for a 10V output into 2kΩ is 5mA. Across 100Ω, that’s 0.5V drop, so you’ll see 9.5V at the terminals. For a 5kΩ load, you’ll see 9.8V. For a 500Ω load, you’ll see 7.5V—not acceptable for full-scale output. If your actuator requires 10V into a low impedance, avoid the 1C1C and use the 1C1B with a buffer amplifier. Most modern actuators have input impedance >10kΩ, so it’s rarely a problem.

Q: How do I visually identify a 1C1C versus a 1C1B if the labels are worn?
A: Look for a small, surface-mount resistor near the output connector on each voltage-configured channel. On the 1C1C, you’ll see 0805-sized resistors (labeled “101” for 100Ω) on the board. The 1C1B has jumper pads but no resistors populated. Use a magnifying glass—the markings are small. You can also measure continuity from the terminal screw to the DAC output pin; on the 1C1C, you’ll read 100Ω; on the 1C1B, it’s near 0Ω.

Q: Does the 1C1C offer any advantage for 4-20mA loops if I never use voltage outputs?
A: No. If you’re always in current mode, the 1C1C and 1C1B are functionally identical. The extra resistor doesn’t matter. Save the 1C1C for applications where voltage outputs and long cable runs coexist. If you’re only driving 4-20mA positioners, the 1C1B is fine and typically cheaper on the surplus market.

Q: Can I convert a 1C1B to a 1C1C by soldering 100Ω resistors onto the board?
A: Technically yes, but not recommended. The PCB has pads for the resistors, so you could populate them. But the resistors need to be precision (0.1%, 25ppm/°C) to maintain accuracy, and you’d need to remove the solder mask carefully. We’ve done it in the repair shop on custom orders. For field work, it’s easier to just buy the right suffix. And if you’re paying for a tech’s time, you’ll spend more on labor than the cost difference between boards.

Q: I’ve got an HCMB1C1B driving a voltage input actuator that occasionally reads high. Could oscillation from the long cable be the issue?
A: That’s a classic symptom of capacitive load oscillation. The 1C1B has no series resistance, so the output stage can resonate with the cable’s capacitance. The 1C1C’s built-in 100Ω resistor dampens that resonance. If you’re stuck with the 1C1B, you can add an external 100Ω resistor in series with the output cable at the board end. That effectively turns it into a 1C1C. We’ve done that in the field on many installations—just solder a resistor into the wire, heat-shrink it, and you’re done. GE’s application note GEH-5838 confirms this fix.

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