DS3800NPSR1A1A | Replacement for NPSR-1A Rack Unit

Description

Product Introduction (Anti-Template)

A rack with a bent backplane pin or a mis-seated power supply will cost you a day of troubleshooting—and probably a service call. The DS3800NPSR1A1A eliminates that headache. It’s a complete factory-assembled Mark VIe rack with the NPSM1A power supply already installed, the backplane torqued to spec, and the fan tray wired and tested. Just bolt it into your 19-inch cabinet, feed it 24V DC, and start sliding in your I/O cards.

The 1A1A suffix tells you exactly what’s inside: the 1A revision of the NPSM power supply, which is the non-isolated 24V input variant. It’s the workhorse of older Mark VIe installs—not as fancy as the “G” with its enhanced EMI filtering, but a solid, proven design. Compared to buying the rack and power supply separately, this assembly saves you about 2 hours of shop time and eliminates the risk of mis-wiring the DC distribution. One plant in Ohio swapped a flooded NPSR1A1A and had their unit back up in under 3 hours.

Key Technical Specifications

Compatible Replacement Models

Frequently Asked Questions (FAQ)

What makes the 1A1A different from the NPSR without any suffix?
The 1A1A suffix is GE’s way of specifying the exact component build. The first “1A” refers to the NPSM power supply revision (NPSM1A, non-isolated). The second “1A” refers to the terminal block revision (early style, screw-clamp). Later revisions like 1G use the newer finger-safe push-in terminals. Functionally, they’re identical—same pinout, same backplane. The only practical difference is the terminal block style. If you’re comfortable with screw terminals, the 1A1A is fine.

Can I swap the NPSM1A for a newer NPSM1G in this rack?
Yes. The rack’s backplane and wiring harness are identical for all NPSM modules. The NPSM1A, 1F, 1G, and even the 1B (125V input) all use the same 24-pin header connector. You can unplug the 1A and plug in a 1G without any modifications. Just verify the input voltage matches your plant—the 1A and 1G are 24V DC input; the 1B is 125V. We’ve done this swap in about 15 minutes, including power-down and power-up.

Is the NPSM1A power supply isolated?
No, the 1A is the non-isolated variant. The 1F and 1G have isolation between input and output (1500V AC). What does that mean for you? If you have ground-loop issues—floating thermocouples, noisy 4-20mA signals—you may benefit from the isolated version. But if your existing 1A has been running fine for years, don’t fix what isn’t broken. We’ve seen more problems from upgrading than from sticking with the original spec.

What’s the cooling fan noise level on this rack?
The two 80mm fans run at 3000 RPM and produce about 35 dBA each—roughly the noise level of a desktop PC. It’s noticeable but not deafening. If your cabinet is in a control room with other equipment, it’ll blend in. If it’s in a quiet office, you might hear it. The fans are standard units; if noise is a concern, you can replace them with lower-speed models (2000 RPM), but that reduces airflow to about 25 CFM total. Not recommended for ambient temps above 40°C.

Can I run this rack without the cooling fans?
Absolutely not. The backplane and power supply are rated for 55°C with the fans. Without airflow, the internal temperature can reach 70°C within 30 minutes at 200W load—you’ll shorten component life significantly (roughly half the MTBF per 10°C rise). We’ve seen one plant try this in a cleanroom, thinking the ambient was cool enough. They lost the power supply in 6 months. Keep the fans running.

What happens if I plug an I/O card into the wrong slot?
The Mark VIe backplane is keyed—the PCI-style connectors have a specific pinout for each slot type. Analog cards go in slots 1-4, digital in 5-8. If you try to force a card into the wrong slot, the keys will prevent it from fully seating. If you do manage to force it (and we’ve seen it), you’ll likely bend pins on the connector and damage the backplane. Our advice: consult your cabinet layout drawing. Slots are numbered left to right when facing the rack.

How do I verify the rack’s backplane is good before installing I/O cards?
Simple power-up test: feed 24V DC, measure the output rails at the terminal strip (+5V, +15V, -15V). If all three are within tolerance, the NPSM is good. Then, plug a known-good I/O card into slot 1. If the CPU recognizes it in ToolboxST, the backplane communication bus is intact. If it doesn’t, you’ve got a backplane issue—often a cracked PCB trace from shipping damage. We test every rack we ship, but shipping damage happens. Check the anti-static bag for punctures before you even unbox.

What’s your return policy if the rack arrives with bent pins?
We pack these in double-wall boxes with custom foam inserts specifically cut for the NPSR profile. That said, carriers are carriers. If you unbox it and find bent backplane pins or cracked fan blades, take photos immediately. We cover shipping damage under our standard 30-day return window. We’ll either replace the rack or issue a full refund. To be frank, we’ve shipped about 500 of these and had exactly 3 damage claims—all from the same carrier. We switched to a different carrier after that.

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