Key Technical Specifications
| Parameter | Specification |
|---|---|
| Processor | Intel Pentium III up to 1.26 GHz |
| Chipset | Intel 815E |
| Memory | Up to 512MB PC133 SDRAM |
| VME Bus | VME64 (Rev C.1) with PCI-to-VME Bridge |
| Networking | Dual 10/100BaseTX Ethernet |
| Serial I/O | 2x RS-232 (16550 compatible) |
| Storage | IDE Interface (Supports CompactFlash) |
| Graphics | Integrated SVGA (4MB DRAM cache) |
| Expansion | 1x PMC Slot (IEEE P1386) |
| Power | +5V DC via VME backplane |
| Cooling | Passive (Conduction/Cooling Wedge) |
| Form Factor | 6U Eurocard |
Product Introduction
If you are looking at a VMIVME-7750, your plant is probably running on borrowed time. This board is a relic, but it’s a workhorse that still controls critical infrastructure where ripping out the backplane would cost millions. It uses an Intel 815E chipset and a Pentium III processor, which sounds ancient today, but in a dedicated VME64 chassis, it handles deterministic real-time tasks better than most modern commercial PCs ever could.Engineers keep buying these because they are drop-in replacements for failing CPU slots in aging DCS and SCADA systems. With 512MB of RAM and dual Ethernet ports, it has enough headroom to run VxWorks or QNX without choking on legacy I/O polling. Just be warned: this board relies on passive cooling via a conduction wedge. If your VME crate’s cooling fans are clogged with grease or the wedge isn’t torqued down properly, this thing will overheat and lock up faster than you can blink.
Quality SOP & Tech Pitfalls
I don’t trust eBay sellers, and neither should you. Here is what we actually do before we ship this:
- Visual & Counterfeit Check: We inspect the BGA solder joints under magnification and verify the Intel 815E chipset markings.
- Live Rack Test: We mount it in a real VME64 test crate, boot VxWorks, and run a 4-hour memory stress test.
- Electrical Verification: We use a Fluke 115 to verify the +5V rail draw and check for shorts on the PCI bus.
- Firmware Logging: We record the exact BIOS and VME bridge firmware revision so you don’t get a mismatched board.
- Anti-Static Sealing: Packed in a true static-shielding bag, not just a pink anti-static poly bag.
The Engineer’s Warning:
Do NOT ignore the VME P2 connector. The VMIVME-7750 uses the VME64 P2 pins for 64-bit data transfers. If your backplane is an older VME32 spec or the P2 connector is corroded, the board might boot but will throw parity errors or fail to recognize memory. I once saw a tech swap a 7750 into a dusty VME crate, skip cleaning the P2 pins, and spend three days chasing a ghost memory fault. Clean your backplane connectors with contact cleaner before installing this. Also, handle it by the edges. A static zap from your finger can fry the PCI-to-VME bridge, and it won’t show up until you try to talk to the I/O cards.
Installation & Configuration Guide
- Pre-Installation: ⚠️ Power down the VME crate and wait 5 minutes for capacitors to discharge. Take high-resolution photos of the old module’s DIP switches, jumpers, and wiring. Verify your new PSU is delivering a clean 5.0V ±5%.
- Removal: Label every wire. Release the top and bottom DIN rail ejector levers simultaneously to unseat the board safely. Never pry it out by the PCB edge.
- Installation: Copy the DIP switch/jumper settings exactly. This step prevents 90% of “board won’t boot” calls. Slide the new VMIVME-7750 into the guides, ensuring the P1 and P2 connectors mate flush. Tighten the ejector levers to torque the conduction wedge against the chassis.
- Power-On & Testing: Apply power. Watch the front panel LEDs. You should see the heartbeat LED toggle within 10 seconds. Connect to the console port (RS-232) to verify the bootloader passes POST before attempting to load your RTOS image.
Compatible Replacement Models
| Model | Compatibility Tier | Notes |
|---|---|---|
| GE VMIVME-7750-834 | ✅ Drop-in Replacement | Same specs, verify suffix matches your exact thermal/power needs. |
| GE VMIVME-7807 | ⚠️ Software Compatible | Newer PowerPC architecture. Requires VxWorks BSP recompile. Expect 40+ hours of engineering labor. |
| Emerson/GE VMIVME-7805 | ⚠️ Software Compatible | Similar architecture jump. Requires chassis cooling verification and software migration. |
| Custom PCIe-to-VME | ❌ Hardware Mod Required | Requires new backplane and carrier cards. Only do this if you have a $100k+ budget and a 6-month shutdown window. |
Frequently Asked Questions (FAQ)
Can I hot-swap this board in a live VME crate?
Absolutely not. VME is not designed for hot-swapping CPUs. You will arc the backplane and fry the SYSFAIL line. Power down the crate.My old board was a -746000 suffix. Will this -834 work?
Usually, yes. The base VMIVME-7750 hardware is identical, but suffixes denote specific factory options like flash disk size, OS pre-load, or conduction cooling specs. Call us with your exact old suffix so we can verify the thermal and storage differences.Does this board support Gigabit Ethernet?
No. The Intel 82559 controller on this board maxes out at 10/100 Mbps. If you need Gigabit, you have to add a PMC mezzanine card, assuming your VME backplane has enough bandwidth to support it.I lost the DIP switch settings for the VME slot address. What do I do?
Check the silkscreen on the PCB or the original OEM manual for your specific machine. The VMIVME-7750 uses binary DIP switches to set the logical slot address. If you set it to the same address as another CPU in the chassis, you will crash the entire system.How long can I expect this to last in the field?
It’s a Pentium III. It will run until the electrolytic capacitors dry out or the solder joints crack from thermal cycling. Keep the chassis cool and the air filters clean, and it should keep your process alive for another decade. Just make sure you have a spare on the shelf.
