DS200DCFBG2BNC MRP433745 DC feedback and control power supply board

Description

Product Overview

The string a buyer sends — DS200DCFBG2BNC MRP433745 — is two identifiers stacked, and they answer different questions. DS200DCFBG2BNC is the hardware identity, written in GE’s DS200 grammar: DS200 the Mark V board series, DCFB the function (DC Feedback), G normal conformal coating, 2 the Group 2 hardware configuration, then three revision letters B primary functional, N secondary functional, C artwork. MRP433745 sits on the ordering side: an MRP number is the material reference GE attaches to an orderable item, the kind of number that appears on a bill of materials and on a pick list, not on the function name.

Both layers matter, and the second one is far less reliable in the secondary market than buyers assume. This same board code is quoted with several different MRP numbers across the trade — 420024, 445970 and 56966 appear on different pages — and, in the other direction, MRP433745 itself is printed on pages for completely unrelated GE models, including a CE4002S1T2B5 page whose own body text names yet another board. MRP numbers are real and they are used the way GE uses them elsewhere in Speedtronic: the Mark VI terminal board IS200TDBTH6ABC carries MRP768176 and the EX2100 relay driver IS200EXHSG3AEC carries MRP528516, pairings that read like the one-to-one assignments they are meant to be. But once a number enters the resale channel it gets copied, recycled and attached to whatever page a seller has just built. The practical conclusion is uncomfortable but correct: the MRP number confirms an order line when it matches the plant’s own documentation, and it cannot establish identity on its own.

What the hardware is, on the other hand, is well defined. A DCFB is one of the load-bearing cards of a Mark V cabinet, and it does two jobs that later architectures split across separate boards. It generates control-level power — +5 VDC at 4 A for logic, ±15 VDC for the operational amplifiers, ±24 VDC for field and excitation duty — plus a dedicated motor field supply and an auxiliary driver for the cabinet’s cooling fans. And it instruments the machine: armature voltage and current, excitation or field current, AC line current, and the amplitude and phase sequence of the AC line. The board also provides the drive circuits for the armature SCR gate pulse generators, which is why its degradation shows up first as firing asymmetry rather than as a clean trip.

The AC input comes from a CPT tap at 38 to 115 VAC, selected by DIP switch and transformer tap together. Bridge and motor voltage feedback is converted to frequency inside the board through VCO circuits, a conversion that keeps a low-level measurement readable inside a cabinet full of SCR switching noise, and the seven DIP switches scale those VCO ranges. Twelve jumpers (JP1 through JP12 where all twelve are fitted) carry the remaining customer configuration. Both are established at build time; a replacement board that arrives with generic defaults produces plausible, wrong numbers, and the loop will run happily on them.

One signal ties the board to the processor in a way every technician should know. /PSEN, routed on the 2PL connector, holds TTL low while the +5 VDC rail regulates and tells the drive control microprocessor to stay active; if regulation fails, it goes high and the processor resets. A marginal +5 rail therefore presents as a controller that will not stay up, not as a voltage fault — and the fault is on this board.

Faults are legible if the map is known. FU1, a ½ A 2AG fuse on the 115 VAC output, is watched by neon lamp LT1; FU2 and FU3, 7 A 2AG fuses on the +5 VDC outputs, are watched by LEDs CR51 and CR55. A lit LED here means a blown fuse — an inversion that catches people who read the panel the way they read every other board in the cabinet. Five test points — P5, DCOM, P15, N15, ACCT — make the rails and the AC current feedback measurable in place.

Physically it is a Mark V standard-footprint assembly at roughly 0.91 kg, made in the USA, normal (G) coating, with 18 plug connectors and 9 stab connectors, P1A being the high-voltage connection for the positive leg of the DC bridge. It is ESD-sensitive and retains lethal surface voltage after the primary AC is isolated.

The trade’s descriptions of this part are, in the main, fiction, and the MRP433745 pages are a fair sample: one gives four BNC front connectors, a 96-pin DIN rear connector and Ethernet with three slots of eight ports; another gives a 6U Eurocard at 233 × 160 × 30 mm weighing 250 g, with dual-channel LVDT redundancy and anti-sulfide coating, in a −25 to +70 °C envelope. There is no coaxial connector on a DCFB, no DIN connector, no Ethernet, no LVDT channel, and the card is neither 6U nor 250 g. A third page labels the same number a Mark VIe DC field bus termination board, which is a different product class on a different platform.

Technical Specifications

DS200DCFBG2BNC MRP433745

Key Features and Advantages

Two numbers, two jobs: the DS200 code tells you what the card does and which revision stack it carries, while the MRP number tells you which order line it was bought on. Keeping those roles separate is what prevents the most expensive mistake in this part of the market — ordering a correct-looking board because a marketplace page glued the right MRP onto the wrong product.

Four circuits consolidated on one card: AC and DC monitoring, control-level power supply, motor and generator excitation supply, and the gate-pulse drive circuits for the armature SCRs. In a cabinet where every slot is budgeted, this consolidation is what keeps Mark V’s card count down — and it is why one failed board can present as a processor fault, a feedback fault or a firing fault depending on which circuit died first.

The /PSEN handshake as a diagnostic: a TTL low on 2PL means the +5 rail is in regulation and the drive control microprocessor is cleared to run; a high forces a reset. That turns “the controller keeps rebooting” into a measurement at one rail, and it explains why a power board swap so often resolves what looked like a logic problem.

VCO feedback conversion, with a caveat: converting bridge and motor voltage to frequency before it leaves the board is the right answer to an SCR noise environment, and it is why this card’s feedback is usable at all. The caveat is the DIP-switch scaling — a board from a different drive application produces clean, credible, wrong values, and nothing in the control system flags it.

Measurement breadth at commissioning level: armature voltage and current, field or excitation current, AC line current, and AC line voltage amplitude and phase sequence. Phase sequence is the check that catches a rotation error at the CPT or a dropped leg before the drive is asked to run, and having it on the same card that supplies the logic means one instrumented point covers both.

Fuse and lamp correspondence documented rather than guessed: FU1 with neon LT1 on the 115 VAC output, FU2 and FU3 with LEDs CR51 and CR55 on the +5 outputs. Three fuses, three indicators, one table — enough to separate a supply fault from a load fault without hunting for a schematic, provided the technician reads the indicators as fault lamps rather than as status lamps.

Configuration discipline as a feature of the process, not of the board: twelve jumpers and seven DIP switches are factory-set for a specific drive application. The working practice is to read them off the outgoing board, photograph them, and configure the replacement identically before it is installed — a five-minute step that removes an entire class of “new board, wrong readings” failures.

Honest limits: this is a Mark V card. It has no field bus, no Ethernet port, no coaxial connector, no DIN-rail housing, no IP rating and no LVDT channel. Every listing that describes those things is describing a different product, whatever number is printed on the page.

Applications

Mark V turbine control cabinets: gas and steam turbine Speedtronic installations use the DCFB for control-level power and for the feedback that the fuel-gas valve, IGV and auxiliary drive circuits depend on — the layer where a rail sag becomes a start-up sequence that aborts without a clean cause.

Generator excitation systems: the board carries the motor and generator excitation supply circuits along with field current measurement, so an excitation system built on DS200 hardware relies on it for both the field supply and the regulator’s current feedback.

GE drive cabinets of the same generation: DC2000, AC2000, CB2000, ME2000 and FC2000 drives use boards, and the DCFB is the power and feedback card within that family. This is also why a turbine-control spare and a mill drive spare can legitimately share a part number — and why the MRP number, which tracks the order line, is the layer that distinguishes which cabinet the board was bought for.

Metals drives: DC rolling mill and coiler drives, where armature current feedback fidelity sets strip gauge; the ACCT test point is the fastest way to separate a feedback problem from a firing problem on a mill that is producing off-gauge strip.

Paper machines, large pumps and fans: multi-motor sections needing section-to-section speed consistency, running on DC drives whose regulators close on this board’s feedback and whose logic runs on its +5 rail.

Life extension of legacy cabinets: plants keeping Mark V in service past mainstream vendor support, where the practical strategy is configured spares of the boards that fail most, ordered against both the code and the plant’s MRP reference, and verified on the label at goods-in.

Where the number does not apply: Mark VIe cabinets and their I/O packs and terminal boards; modern drives with field bus interfaces; anything expecting a DIN-rail power supply. Those are different products with different numbers, and conflating them is how the MRP433745 pages ended up describing four BNC connectors and a 6U Eurocard.

Related Products

DS200DCFBG1B — Group 1 revision of the same DC feedback power supply board; different hardware grouping, same function. DS200DCFBG1BNC — Group 1 with the B/N/C revision stack; the board most often confused with DS200DCFBG2BNC in listings and not interchangeable without checking cabinet configuration. DS200DCFBG1BLC — Group 1 with an L-rated secondary revision, a later revision level in the same family. DS200DCPAG1ACB — the DC power supply board in the series, a distinct power card sharing the same cabinets. DS200LDCCH1A — drive control and LAN communications board, the processor side that reads /PSEN and the ACCT feedback. DS200FGPAG1AHD — gate pulse amplifier, driven from this board’s gate-pulse drive circuits; the pair that explains firing asymmetry symptoms. DS200ACNAG1ADD — ARCNET communication interface card for Mark V, part of the same cabinet board set. IS200TDBTH6ABC (MRP768176) — Mark VI TMR discrete terminal board; cited here because its MRP pairing illustrates how the MRP layer is meant to work, one board to one number. IS200EXHSG3AEC (MRP528516) — EX2100 exciter high-speed relay driver board, another clean MRP pairing; proves the MRP system is GE-wide rather than -specific. MRP420024 / MRP445970 / MRP56966 — further material numbers quoted against DS200DCFBG2BNC in the trade; reconcile each against the plant’s bill of materials instead of selecting on the number alone.

Installation and Maintenance

Before installation: reconcile all three layers before the board is ordered or fitted — the code, the revision stack (Group 2, B primary, N secondary, C artwork) and the MRP number against the cabinet’s bill of materials. If the MRP on the label disagrees with the plant’s documentation for that slot, stop and resolve it; a number that has been recycled across models in the resale channel is not evidence of correctness. Isolate the drive, apply lockout/tagout, and wait for capacitor discharge — the card retains lethal surface voltage, and the neon lamp on the 115 VAC output exists because that potential persists. Work grounded and on an antistatic surface. Photograph the twelve jumpers and seven DIP switches on the outgoing board, since they encode the drive application’s line voltage and feedback scaling.

Installation: seat the card and verify all 18 plug connectors and 9 stab connectors, particularly P1A on the DC bridge positive leg and the 2PL connector carrying /PSEN; a partially mated stab connector heats and arcs under load instead of failing cleanly. Confirm the CPT tap matches the DIP-switch selection before energising. On power-up, check that LT1, CR51 and CR55 are all out, measure P5, P15 and N15 against DCOM, and confirm /PSEN transitions as the +5 rail comes into regulation.

Maintenance: start diagnosis at the fuse map — a lit CR51 or CR55 means FU2 or FU3 has opened, and the real question is what drew the current. Never replace a 7 A 2AG fuse on a +5 rail without finding the cause. Keep the cabinet’s forced ventilation healthy, because this board drives the cooling fans and a hot cabinet shortens the electrolytic life on the card itself. Log the code, MRP number and jumper/DIP configuration for every DCFB in the fleet, and hold configured spares per cabinet type: the board sits upstream of both the logic and the firing circuits, so its failure takes the whole drive down.

Warranty and Quality

Every DS200DCFBG2BNC MRP433745 is supplied as a GE Speedtronic Mark V DC feedback and control power supply board, verified against the full suffix stack and against the material number quoted on the order line, with any discrepancy between the two stated before dispatch rather than discovered at the cabinet. Because the MRP number is widely recycled in the secondary market, verification is done on the physical label and the plant’s documentation, not on a marketplace page. Units are inspected for stab-connector arcing and wear, plug-connector pin condition, conformal coating integrity, electrolytic condition, fuse and indicator state, and prior rework; where a Mark V bench arrangement is available the card is energised, the three rails are measured at P5, P15, N15 and DCOM, the fuse indicators are confirmed out, and the /PSEN transition is checked. A 12-month repair, replacement or refund commitment applies. Technical support covers what this dual number actually raises: how the code and the MRP number differ in purpose, why the same board appears under several MRP numbers, why the same MRP number appears on unrelated GE models, how Group 2 differs from Group 1, and which rail to measure when a drive controller will not stay up.