The IS200TAMBH1ABA is an Acoustic Monitoring Terminal Board (TAMB) manufactured by GE Energy as part of the Mark VI™ turbine control system. This terminal board is designed to interface with the VAMB (Acoustic Monitoring I/O sub‑assembly) to provide signal conditioning for dynamic pressure sensors used in gas turbine combustion monitoring. The TAMB supports up to nine channels of acoustic signal input per board, and up to two TAMB boards can be connected to a single VAMB, providing a total of 18 channels for monitoring combustor dynamics (flame detection and pressure pulsations) in GE frame 6, 7, or 9 gas turbines.
The IS200TAMBH1ABA accepts low‑level millivolt outputs from third‑party charge amplifiers or sensors from vendors such as Bentley‑Nevada®, Vibro‑meter®, PCB Piezotronics®, GE Power System’s Charge Converter Signal Amplifier (CCSA), and GE/Reuter‑Stokes®. The board provides flexible power supply options for the sensors, including current‑limited +24 V dc and ‑24 V dc outputs, as well as a constant current source (4 mA) for certain sensor types. Each channel includes configurable jumpers for selecting voltage or current input, and for tying the return line to power common or leaving it floating. The board also features buffered BNC outputs for each channel, allowing direct monitoring of the dynamic pressure signal (with DC bias removed).
The TAMB is mounted in the turbine control cabinet and connects to the VAMB board (located in the I/O rack) via a 37‑pin cable. The board has no on‑board LEDs or fuses; diagnostics are reported through the VAMB and the Mark VI control system. The IS200TAMBH1ABA is a simplex (non‑redundant) terminal board and is intended for use only in simplex configurations.
Functional Description
The acoustic monitoring function is critical for detecting combustion instabilities (e.g., screech, rumble, or other pressure fluctuations) in gas turbine combustors. The IS200TAMBH1ABA provides 18 channels of signal conditioning (when two boards are used) with the following capabilities:
Differential inputs with adjustable gain (1, 2, 4, or 8) to optimise signal resolution.
Fast synchronous sampling with 8x over‑sampling to minimise analog filtering.
Open wire detection via a high‑impedance DC bias that can be set to +28 V, ‑28 V, or ground.
Support for both voltage and current (4‑20 mA) input modes via hardware jumpers.
Power supply for external charge amplifiers: each channel provides a current‑limited +24 V and ‑24 V output, plus a constant current (4 mA) source selectable by the VAMB.
Buffered BNC output for each channel (signal minus DC bias) for external monitoring or troubleshooting.
On‑board serial EPROM for board identification (type, revision, serial number, and connector location) which is read by the VAMB for hardware verification.
The TAMB receives an mV‑level differential signal from the sensor or charge amplifier. The differential pair consists of SIGx (signal) and RETx (return). The board provides electromagnetic transient suppression and passes the conditioned signal to the VAMB via a 37‑pin connector (J1A or J1B). The VAMB performs analog‑to‑digital conversion, DC bias removal, RMS calculation, Fast Fourier Transform (FFT), and alarm detection.
Hardware Characteristics
The IS200TAMBH1ABA is a printed wiring board designed for mounting inside the Mark VI control cabinet. It has a 48‑pin customer terminal block (TB1/TB2), two 37‑pin D‑sub connectors (JA1 and JB1) for connection to the VAMB, and nine BNC connectors (BNC1 through BNC9) for buffered outputs. The board is powered from the VAMB via the 37‑pin cable; no separate power input is required.
Connectors and Terminals
Connector / Terminal | Type | Description |
TB1 / TB2 (48 pins total) | Euro‑style terminal block | Customer field wiring for 9 channels: each channel has pins for P24V, N24V, SIG, RET, and PCOM. Also includes DIAG, DIAGRET, and SCOM. |
JA1 | 37‑pin D‑sub female | Connects to VAMB board (primary interface for channels 1‑9). |
JB1 | 37‑pin D‑sub female | Connects to second TAMB board (when 18 channels are required) or remains unused. |
BNC1 to BNC9 | BNC female (front panel) | Buffered output per channel: signal after DC bias removal, gain = 1, 40 Ω output impedance. |
Terminal Point Definitions (Partial – 48 pins)
Signal Name | Pin # | Description |
PCOM | 1, 6, 11, 16, 25, 30, 35, 40, 45 | Power supply return for P24V or N24V supplies. |
P24V1 | 2 | +24 V output (current‑limited) for channel 1 charge amplifier. |
SIG1 | 3 | Differential signal input (positive) for channel 1. |
N24V1 | 4 | -24 V output (current‑limited) for channel 1 (used with Bentley‑Nevada). |
RET1 | 5 | Differential return input for channel 1. |
... (similarly for channels 2‑9) | ... | ... |
DIAG | 46 | Diagnostic DAC output from VAMB. |
DIAGRET | 47 | Return for diagnostic DAC output. |
SCOM | 48 | Shield ground for cable shielding. |
Jumpers
Each channel has two jumpers:
Jumper | Type | Function |
JP2, JP4, JP6, JP8, JP10, JP12, JP14, JP16, JP18 (even numbers) | 3‑pin jumper (I_IN / V_IN) | Selects current input (with 250 Ω burden resistor) or voltage input. |
JP1, JP3, JP5, JP7, JP9, JP11, JP13, JP15, JP17 (odd numbers) | 3‑pin jumper (OPEN / PCOM) | Connects RETx to PCOM (ground) or leaves it floating (OPEN). |
Bias Control
The TAMB allows the VAMB to apply a DC bias voltage to the signal and return lines for open‑circuit detection. The bias is controlled by two TTL signals per channel (BIASP and BIASN) from the VAMB:
BIASP | BIASN | Result |
False | False | No bias; SIGx and RETx pulled to ground. |
False | True | -28 V bias applied. |
True | False | +28 V bias applied. |
True | True | Illegal (prevents short circuit). |
Constant Current Select
For sensors requiring a constant current source (e.g., PCB Piezotronics), the VAMB can assert the CCSELx signal (TTL high) to enable a 4 mA constant current source on the P24V line. This is used instead of the voltage‑limited supply.
Configuration and Setup
The IS200TAMBH1ABA has no on‑board processors or configurable firmware; all configuration is performed through the VAMB board using the ToolboxST software. Key configuration parameters per channel include:
InputUse – Selects sensor type (Bently‑Nevada, Vibro‑meter, CCSA, PCB, GE/Reuter‑Stokes, Custom, or File).
Gain – Sets the hardware gain (1, 2, 4, or 8) to avoid saturation.
Low_Input / High_Input – Defines the millivolt range for engineering unit conversion.
Low_Value / High_Value – Defines the corresponding engineering units (e.g., psi).
CCSel – Enables constant current mode (True/False).
BiasLevel – Sets the DC bias voltage for open circuit detection (when InputUse = Custom).
SysLimit1 / SysLimit2 – Configurable high/low limits for alarm generation.
DiagOCChk, DiagBiasNull, DiagSigSat – Enable/disable specific diagnostics.
Hardware jumpers must be set according to the sensor type and wiring method (3‑wire or 4‑wire). The document provides a detailed table (reproduced below) for jumper positions:
Vendor | Model | Wiring | JPn (odd) | JPn (even) |
Bentley‑Nevada | 350500 | 3‑wire | PCOM | V_IN |
Bentley‑Nevada | 350500 | 4‑wire | OPEN | V_IN |
Vibro‑meter | IPC 620/704 with GSI 122/130 | 3‑wire | PCOM | V_IN |
Vibro‑meter | IPC 620/704 with GSI 122/130 | 4‑wire | OPEN | V_IN |
GE CCSA | – | – | OPEN | V_IN |
PCB Piezotronics | 111A21, etc. | – | PCOM | V_IN |
GE/Reuter‑Stokes | Flame Tracker RS‑FS | – | PCOM | I_IN |
Diagnostics and Alarms
The TAMB board has no on‑board LEDs. Diagnostics are reported by the VAMB as board‑level and channel‑level alarms. Common alarms include:
Fault Code | Description | Possible Cause |
18‑21 | Incorrect J3/J4/J6/J7 terminal board ID | Cable not connected to TAMB, wrong TAMB, or defective board. |
41‑58 | Sig x: Open Ckt Test Failed | Open circuit in sensor wiring or sensor failure. |
61‑78 | Sig x: Bias Nulling Error | DC bias out of range for selected sensor type; check InputUse configuration. |
81‑98 | Sig x: Input Signal Saturated | Signal exceeds 10 V after gain; reduce Gain or check sensor. |
101‑118 | Sig x: Sensor Limit Exceeded | Peak voltage exceeds limit for selected sensor type. |
The VAMB also provides three front‑panel LEDs:
Green – Flashing indicates normal RUN.
Red – Solid indicates FAIL.
Orange – Steady indicates a diagnostic alarm exists.
Installation and Replacement Procedures
Handling Precautions
Static sensitivity – The IS200TAMBH1ABA contains static‑sensitive components (EPROM, jumpers, etc.). Always wear a wrist grounding strap and handle the board at a grounded workstation.
De‑energise before handling – Turn off power to the I/O rack and the VAMB board before connecting or disconnecting cables to the TAMB.
Do not insert or remove with power applied – May damage the board or the VAMB.
Installation Steps
Mount the TAMB board in the control cabinet using the provided mounting holes.
Connect the 37‑pin cable from the VAMB (J3 or J4) to the TAMB’s JA1 connector (for channels 1‑9). If using a second TAMB for channels 10‑18, connect a second cable from VAMB J6 or J7 to the second TAMB’s JA1.
Set the jumpers (JP1‑JP18) according to the sensor type and wiring method (refer to the jumper table).
Wire field sensors to the 48‑pin terminal block (TB1/TB2) using the appropriate terminal points (P24Vx, N24Vx, SIGx, RETx, PCOM).
Connect the shield ground to SCOM (pin 48) if required.
Connect the buffered BNC outputs to monitoring equipment if needed.
Apply power to the VAMB and verify that the green LED flashes and that no alarms appear in the ToolboxST diagnostics.
Replacement Procedure
De‑energise the VAMB and the I/O rack.
Label and disconnect all cables from the TAMB (37‑pin, BNC, and field wiring).
Remove the board from its mounting.
Set jumpers on the new IS200TAMBH1ABA exactly as on the old board.
Mount the new board and reconnect all cables.
Restore power and verify operation via ToolboxST.
When ordering the IS200TAMBH1ABA, use the complete part number exactly as shown. The part number follows GE’s convention:
IS200 – Innovation Series, 200‑class.
TAMB – Functional acronym: Acoustic Monitoring Terminal Board.
H1 – Generation/version.
A – Base designator.
B – Modifier (e.g., component variation).
A – Revision A.
Warranty and Order Placement
Warranty replacements (within warranty period): Contact GE Energy Post Sales Service (contact details omitted per request).
Spare parts or non‑warranty orders: Contact your nearest GE Sales or Service Office. Provide:
Complete part number: IS200TAMBH1ABA
Turbine control system serial number
Material List (ML) number
Note: All digits and letters in the part number are significant. GE may substitute later compatible revisions, but backward compatibility is assured.
