TEKTRONIX TCPA300/400 current probe amplifier

2. Core testing items (amplifier+probe)

(1) DC gain accuracy test (taking TCP305 as an example)

Equipment connection: current source → 5-turn current loop → probe → amplifier → DMM (50 Ω terminal);

Test steps:

After demagnetization, the probe clamps the current loop and the current source outputs+1.00A;

Record the DMM voltage value M1, and then output -1.00A to record M2;

Calculation error:% Error=[(M1-M2) -2 × VE]/(2 × VE) × 100% (VE is the expected voltage, such as 1A corresponding to 1V in the 5A/V range);

Qualified range: ≤± 3% (guaranteed value), ≤± 1% (typical value).

(2) Bandwidth test (using TCP312 as an example)

Equipment connection: level sine wave generator → high-frequency current loop → probe → amplifier → oscilloscope;

Test steps:

The generator outputs a 3MHz, 3Vpp signal and records the oscilloscope peak to peak value M1;

Adjust the generator frequency to 100MHz (TCP312 bandwidth) and record M2;

Verification: (M2/M1) × 1.18 ≥ 0.707 (1.18 is the impedance correction factor);

Qualified range: -3dB bandwidth ≥ 100MHz.

(3) Rise time test (taking TCP404XL as an example)

Equipment connection: High voltage pulse generator → Built in current loop → Probe → Amplifier → Oscilloscope;

Test steps:

The generator outputs 5A, 250 μ s pulses, and the oscilloscope is set to 80ns/div;

Measure the rise time of pulses ranging from 10% to 90%;

Qualified range: ≤ 175ns (derived from a bandwidth of 2MHz: 0.35/2MHz=175ns).

3. Calibration adjustment (only operated by qualified personnel)

(1) Amplifier adjustment (TCPA300)

Prerequisite: The casing needs to be disassembled and a calibration adapter (174-4765-00) needs to be used;

Step: The current source outputs 0.100A, adjust the corresponding range potentiometer (such as adjusting the 25 Ω potentiometer for 5A/V) to make the DMM voltage meet the expected value (such as 0.1A corresponding to 0.25V at 5A/V range).

(2) Probe adjustment (TCP305/312)

DC gain adjustment: Open the probe housing and adjust the DC gain potentiometer to make the DMM voltage error ≤ ± 3% (refer to Table 6-7);

Attention: Record the original position before adjustment to avoid exceeding the specifications.

Troubleshooting and Maintenance

1. Common faults and solutions

Possible causes and solutions for the fault phenomenon

Demagnetization failed (LED red), 50 Ω load not connected, probe not locked, check terminal+lock slide cover

OVERLOAD LED constantly on, current exceeding range, probe overheating, current reduction+power-off cooling+demagnetization

The measurement value is not accurate without demagnetization, the range is selected incorrectly, the terminal is not connected to demagnetization+check the range+check the 50 Ω load

The probe without output signal is not connected, and the coupling is set to AC (measuring DC). Connect the probe and switch the DC coupling

2. Interpretation of Error Code

Display mode: AC/DC coupled LED flashes alternately, and 4 fault LEDs (PROBE OPEN is MSB, NONCOMPATIBLE is LSB) display a 4-digit binary code;

Common code:

Code 1: No Hall element detected in the probe → Reconnect or replace the probe;

Code 2: DC offset calibration failed → restart amplifier+demagnetization;

Code 15: Internal software error - If restarting is ineffective, contact after-sales service.

3. Daily maintenance

Cleaning: Wipe the outer shell with 75% isopropanol, and do not use solvents such as benzene/acetone;

Storage: Non working temperature -40 ℃ -+75 ℃, avoid moisture/dust;

Calibration cycle: It is recommended to calibrate once a year, with a reference frequency error (± 10ppm) valid for one year.

Accessories and Replacement Parts

1. Standard accessories (included with the product)

Category, accessory name, purpose

Amplifier accessory 50 Ω straight through terminal (011-0049-02) matching output impedance

Connect the TEKPROBE interface cable (012-1605-00) to the TEKPROBE oscilloscope

BNC line (012-0117-00) connected to non TEKPROBE oscilloscope

Probe accessories Probe cover (016-1923-00) protects the probe

Grounding lead (196-3120-01) probe grounding

2. Key replacement parts (partial)

Component type, model, and part number

TCPA300 motherboard circuit motherboard 671-5434-00

TCP305 coil current transformer component 120-184-00

TCP404XL cable probe cable assembly 174-4816-00

Amplifier fan axial fan (12VDC) 119-6721-00