DS200DCFBG2BNC: Function and Diagnostics

DS200DCFBG2BNC is a G2-group DCFB, GE's Power Supply Board for the EX2000 excitation control system, also used across the DC2000, AC2000, CB2000, FC2000, GF2000, and ME2000 IGBT drive families. It delivers control-level power to the drive or exciter and 115 VAC power to the enclosure cooling fans, using 38 VAC and 115 VAC input from the control power transformer (CPT). Onboard circuitry includes control-level power supplies (+5 V, ±15 V, ±24 V), motor/generator field power circuits, driver circuits for the armature SCR gate pulse generators, and instrumentation circuits monitoring AC line current and voltage.

The DCFB is wired directly to the SDCC drive control card (or LDCC on EX2000 systems) through the 1PL and 2PL connectors. The CPT's 38 VAC input is rectified and filtered into ±24 VDC (+24 V at 3 A, -24 V at 1 A); onboard regulators derive ±15 VDC from those rails, and the +24 VDC supply also produces a +5 VDC, 4 A output. Voltage-controlled oscillator circuits on the board convert several analog feedback signals – SCR bridge input voltage, output bridge voltage, and armature/field shunt signals – into a frequency signal (nominally 250 kHz, ranging 0–500 kHz) sent to the SDCC/LDCC over connector 1PL, where DIP switches on the DCFB scale each signal to match the installation.

Diagnose the Fault Before You Order a Replacement

A DCFB fault and an SDCC/LDCC fault can look identical from the fault display, because the DCFB's +5 VDC output directly controls whether the drive control card's microprocessor stays running. The /PSEN signal on 2PL sits TTL-low when that 5 V rail is properly regulated, and switches high – forcing an SDCC/LDCC reset – the moment it sags. A drive or exciter that resets repeatedly on its own is worth checking against the DCFB before you replace the drive control card. Before ordering any replacement board:

• Check the DCFB's fuse-status LEDs. CR51 and CR55 flag a blown FU2 or FU3 (7 A power-output fuses); a neon lamp at LT1 flags a blown FU1 (1/2 A, on the 115 VAC fan output).
• Measure the +5 V and ±24 V rails feeding the SDCC/LDCC before assuming its own logic has failed.
• Treat repeat failures in the same slot as a downstream issue first. Field experience on Mark V/EX2000 systems consistently shows that a card position failing again and again points to a field device, wiring, voltage, or current problem – not a bad batch of boards.
• Watch the companion drive control card. There are documented cases where a DCFB and its companion LDCC failed together and the actual root cause was a burnt capacitor on the LDCC, not the DCFB. GE never released full schematics for this card generation, so a specialized repair shop with card-level test equipment is often the fastest way to a confirmed answer.

What G2BNC Means

DS200 is the board series prefix, DCFB is the Power Supply Board acronym, G2 is this board's product grouping, and BNC is the specific functional and artwork revision combination of this unit. GE's manual reference for this board is GEI-100028, documented in later printings as GEI-100028C. We have not found a confirmed functional split between G1 and G2 DCFB groups, so treat the group letter as a hardware/manufacturing revision marker and always match the full suffix on the card you're replacing.

Related Boards and Longer-Term Alternatives

The DCFB is closely paired with the SDCC (or LDCC on EX2000) drive control card and the panel's TCPS power supply. For sites evaluating a longer-term platform change, see our Mark V vs Mark VI: DS200 to IS200 guide. For how GE's Speedtronic part numbers are structured, see the GE Speedtronic Part Number Decoder, and for the DCFB's place among other DS200 boards, see GE Mark V DS200 Boards Explained.

What to Send With Your Quote Request

• The complete part number and suffix, e.g., DS200DCFBG2BNC
• A photo of the label
• Turbine/generator model, and whether this feeds an EX2000 exciter or a DC2000/AC2000-family drive
• Quantity needed
• Urgency – planned outage or active fault

Request a Quote

This DS200DCFBG2BNC is offered used, cleaned and tested, with a 1-year warranty (see below). Pricing isn't published online since these quotes depend on exact revision match and current stock – submit a Request a Quote and expect a reply within 24 hours. We ship worldwide DDP, accept purchase orders, and support both planned outages and urgent turbine-down orders.

General Information about the Product
Part Number	DS200DCFBG2B Mark V DS200
Description	GE General Electric DS200DCFBG2B DS200DCFBG2BNC Power Supply Board Mark V
Condition	used Cleaned and Tested. With 1 Year Warranty.