A 486 that still runs gas turbines

A quarter century after the Speedtronic Mark V LM shipped, the 80486DX on this daughterboard still earns its keep moving live turbine data between I/O hardware and the Control Engine. The DS200UCPBG6A — this unit carries revision tail DA — is the IO Engine CPU board of the Mark V LM, the Speedtronic variant GE paired with its aeroderivative gas turbine line. The architecture gives each of four IO Engines (<R1>, <R2>, <R3>, and <R5>) its own processor: this board, mounted as a daughtercard on the DS200STCA in rack location 1. GEH-6153 describes its job as the IO "switchboard" between Control Engine and I/O cards — packaging conditioned signals into COREBUS packets on a 10 ms schedule and receiving output packets back — and supplier documentation lists the hardware that does it: the 486 CPU, DRAM on a SIMM, flash EPROM holding the ROM BIOS, two RS-232 ports, and the ARCNET driver that puts the engine on the bus.

Three checks before you replace a UCPB

The economics of Mark V LM maintenance reward patience in exactly one place: fault isolation. Three checks, in order.

• Scope. If a single measurement or output is wrong, the fault lives on an I/O board or its termination path — TCQA-family analog boards, TCDA digital boards, or wiring. The UCPB signature is all of one core's data going stale at once.
• Power. The TCPS in the same rack is the first hardware suspect for a silent core. Confirm supply health before condemning processors.
• Communications. COREBUS drop cable, BNC connectors, and the UCPB's COREBUS address DIP switches. From the HMI, GEH-6153's MON_SYS screens show which engines the Control Engine can hear; a hard reboot from the core power switch is the approved reset.

If the core stays dark through all three, quote the UCPB — and consider quoting the STCA beneath it at the same time, since removing the assembly is the natural moment to renew both.

Suffix letters, catalog numbers, and compatibility

By GE's own numbering key, printed in the Mark V LM manual: DS = Salem, Virginia; 200 = base-level board; UCPB = function; G6 = group. The next letter, A, is a functional revision without backward compatibility — meaning DS200UCPBG6A is the catalog number you must match. The final letters, D and A on this unit, are backward-compatible functional and artwork revisions. Practical translation: G6A replaces G6A; the DA tail identifies this board's exact build state; and a G5A is a different catalog item, not an older copy of this one. Note also that the market carries later groups of this acronym (supplier listings show a G7 with a different CPU and memory fit), which is one more reason the group digit is not negotiable. If your label reads anything you cannot parse, send it over — or run it through our GE Speedtronic Part Number Decoder.

Boards that share the IO core

The UCPB's immediate world: STCA (motherboard and IONET master), TCQA and TCQC (analog I/O and expander), TCPS (rack supply), QTBA (termination and COREBUS landing). One rack over, TCDA and TCRA handle digital I/O and relay outputs; the protective core runs triple TCEA boards with two-out-of-three voting. The DS200 board ecosystem — what each acronym does and which cores hold it — is mapped in GE Mark V DS200 Boards Explained, and everything we stock for the platform lives in GE Mark V DS200 Boards within the wider GE Speedtronic Turbine Control Boards range.

Your quote request

1. Complete number with tail — DS200UCPBG6ADA — straight from the label.
2. A photo of that label.
3. Control platform and unit type (Mark V LM package; or Mark V Simplex/TMR panel).
4. The failure story in two sentences, including checks already done.
5. Quantity and the date you need it on site.

Shipping and purchase terms

Supplied used, cleaned and tested, with a one-year warranty, as the table below records. Send Request a Quote and we come back within 24 hours. Delivery is worldwide DDP; purchase orders are accepted.