DS3800NEPA1C1B | GE Speedtronic Exp Processor Board

Description

Product Introduction

The DS3800NEPA1C1B is the sibling of the 1C1A we covered earlier. The difference is the final suffix: “B” instead of “A.” That “B” stands for a board that went through a different manufacturing batch—one that uses higher-grade capacitors rated for -40°C to +85°C. The 1C1A is rated for 0-60°C; the 1C1B can handle the extremes. You’ll want this variant if your Mark IV cabinet sits in an uninsulated shelter in North Dakota winters or a desert environment where the ambient temp hits 55°C in the afternoon. Same 40MHz processor, same 1MB dual-port RAM, same expanded math library—just tougher components.

The board plugs into the expansion header on the DMP processor and handles all the heavy lifting—thermodynamic models, vibration analysis, predictive control sequences. GE released the “B” revision as a running change in late 1998. They didn’t change the functionality; they just swapped the electrolytic capacitors from a standard 85°C rated part to a 105°C high-reliability part, and added a conformal coating to the entire board. If you’re ordering for a hot or humid environment, the 1C1B is the safer choice. Compare this to the base NEPA (25MHz, 512KB RAM, 0-55°C operating range). The 1C1B shaves 15ms off a complex 100ms control loop and stays stable when the cabinet temperature hits 65°C.

Key Technical Specifications

Compatible Replacement Models

Frequently Asked Questions (FAQ)

What’s the real difference between the 1C1A and the 1C1B?
The “B” means GE upgraded the capacitors from a 85°C rated part to a 105°C rated part, and added a conformal coating to the entire PCB. That’s it. The processor, memory, and math library are identical. We’ve tested both side-by-side on our test rack at 60°C ambient. The 1C1A runs about 2°C hotter on the processor die and the capacitors are rated for fewer hours at that temperature. The 1C1B is simply more robust. If your cabinet is in a climate-controlled room, you’ll never notice the difference. If it’s on a turbine deck in Houston in August, the 1C1B will outlast the 1C1A by roughly 3-4 years.

Will the 1C1B work with DMP firmware older than v4.0?
No. The 40MHz processor requires DMP firmware v4.0 or later to handle the faster bus timing. If your DMP is running v3.x, the board will down-clock to 25MHz and run in compatibility mode. You’ll see “NEPA Present” in the diagnostics but it won’t deliver the performance improvement. We include a firmware upgrade EPROM with every 1C1B shipment—we pre-program the chips and send you installation instructions. The upgrade takes about an hour and requires the system to be powered down. If you’re not comfortable doing that, call us and we’ll send a technician to your site (we cover most of North America within 48 hours).

Can I mix a 1C1B with a base NEPA in the same rack?
There’s only one expansion slot on the DMP. You can only install one NEPA board per CPU. Mixing isn’t a consideration—you either have a coprocessor or you don’t. If you’re running a redundant Mark IV configuration (dual DMPs), you’d need two NEPA boards, one per CPU. They should match: both 1C1B or both 1C1A. Mismatched boards won’t cause errors—the CPUs run independently—but it makes troubleshooting inconsistent because one CPU will outperform the other. We recommend matching them for symmetry.

What’s the thermal warning LED about?
The 1C1B has a red LED that illuminates when the onboard temperature sensor hits 65°C. That’s a warning—the board will continue to function but the processor is approaching its thermal limit. At 70°C, the board will shut down the math coprocessor and fall back to software math on the DMP (you’ll see a “NEPA Shutdown” message in the diagnostics). The red LED is your early warning. If you see it, increase airflow to the cabinet—open the cabinet door, install a fan, or move the board to a cooler slot in the rack (the rightmost slots tend to run cooler because they’re further from the power supply heat). We include a fan bracket with every 1C1B we ship, and we recommend installing it even if you don’t see the red LED.

How do I verify the board is running at 40MHz and not down-clocked?
Through the Mark IV diagnostic console, navigate to the “Processor Status” screen under the “Hardware” menu. It will display the NEPA’s clock speed. If it says “40MHz,” you’re good. If it says “25MHz” or “Compatibility Mode,” the DMP firmware is too old. The board self-detects the firmware version at boot and adjusts accordingly. You’ll also see the CPU load drop by about 35-40% when you run a benchmark. We test this on every board we ship and include the benchmark results in the test report.

Is the conformal coating something I need to worry about during installation?
No. The coating is a thin acrylic layer that protects the board from moisture, dust, and corrosive gases. It doesn’t affect the edge connector or the mounting holes. The coating makes the board slightly more slippery to handle—use a soft cloth or gloves to grip it—but that’s the only practical consideration. The coating is also why the 1C1B is more expensive than the 1C1A; the coating process adds a manufacturing step. Some customers have asked if they can apply the coating themselves to a 1C1A. We don’t recommend it—you’d need to mask the edge connector and the LED, and the spray-on coatings rarely match GE’s quality.

What’s your return policy and lead time?
We stock the 1C1B in our Houston and Dallas warehouses. Shipping is 1-2 business days domestically, 3-5 business days internationally. We offer a 30-day return window for unused boards, full refund. If you’ve installed the board and it’s not delivering the expected performance, we’ll troubleshoot with you over the phone—it’s almost always a firmware issue or a seating problem. If the board is genuinely defective, we replace it at no cost (we cover the return shipping). If the board is functional but you want to swap to a different revision, we charge a 15% restocking fee. To be direct: we’ve processed exactly three returns on the 1C1B in the last two years. Two were compatibility issues (old DMP firmware), and one was a bent pin on the expansion connector (customer error). The board itself is rock-solid. We’re confident enough to offer a 60-day “no questions asked” return policy for any compatibility concern. Call us if you’re unsure—we’ll walk you through the DMP revision check before you order.

A-B 6181X-12A2SW71DC
TRICONEX 3721
ABB 5SHY3545L0010