Two Names, One Board

GE's technical documentation refers to this board both as the "RST Overflow Board" and as the "Analog IO Expander Board" — both names describe the DS200TCQCG1B. It occupies position 4 of each of the Mark V's <R>, <S>, and <T> cores, adding to the analog I/O capacity already provided by the TCQA (position 2) and the TCQB (position 3, when present).

What It Does

Besides extending the core's analog capacity, the TCQC supplies the excitation voltage required by the position LVDTs and performs the digital-to-analog conversion representing the called-for fuel flow requested by the control system. It also maintains two DENET connections, forming a passive six-port bridge for that network.

A Dependency Worth Knowing

The TCQC doesn't operate alone: it depends on the presence and correct operation of the TCQA (and the TCQB, where applicable) on the same core. A symptom that appears to originate on the TCQC can actually start on one of these upstream boards. Before replacing the TCQC, confirm the TCQA on the same core is healthy.

Diagnose Before You Buy

A case reported by Mark V engineers on a technical forum illustrates the trap well: out-of-spec voltages associated with the TCQC led to swapping the TCQC itself, the TCQA, and the core's TCPS, without resolving the problem. The most likely cause identified afterward was a mismatch between the DIAGC.DAT calibration file and the boards/PROMs actually installed — not a physically faulty board. Before requesting a new TCQC over a voltage alarm:

• Check the TCPS fuses (the core's power supply) before suspecting the TCQC.
• Compare the board and PROM revisions installed against what the system expects.
• Only physically replace the board after ruling out these software/calibration causes.

Not Every Mark V Has a TCQC

Whether a TCQC is present depends on the number of analog channels the application requires. Before ordering a replacement part based solely on a bill of materials, physically confirm that the core in question actually has this board installed.

Reading the Part Number

DS200TCQCG1B is the base reference; DS200TCQCG1BAA is the full revision stamped on the physical label. Always provide the complete code when requesting a quote.

This Unit

Used, cleaned and tested, with a 1-year warranty.

Details for Your Quote

• Full part number with suffix (photo of the label)
• Affected core and the status of the TCQA on the same core
• Mark V Simplex or TMR
• Urgency

Request a quote through Request a Quote: response within 24 hours, worldwide DDP dispatch, purchase orders accepted.

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