Repair of the Chroma 63204 5.2kW DC load


Chroma ATE is well known player for high-power DC and AC power solutions test equipment. Today in this article we will repair and test very heavy Chroma Model 63204 DC load, rated for nominal 5.2kW capacity, with maximum 500V or 100A DC levels.

This unit has next set of main features:

  • 5200W rated power at ambient temperature 0 to +25 °C, derated to 4000W at +40 °C
  • Maximum current 100A, maximum voltage 500V. Multiple units can be paralleled for greater powers.
  • Minimum operating voltage 1.25 V for 50A load, 2.5V for 100A load.
  • Current setting 2.8/28 mA resolution, 0.1% of setting + 0.1% accuracy FS.
  • Programmable slew rate from 0.016A to 4A/µs, load level, load period and voltage Von
  • Programmable dynamic test modes with speeds up to 20 kHz, timing resolution 1 ms
  • Constant Current, Constant Resistance, Constant Voltage, Constant Power modes
  • True floating load input with remote 4-wire sense
  • Remote RS-232C, RS-485, GPIB interfaces
  • 15-bit A/D converter for accurate measurements
  • Short-circuit simulation mode
  • Isolated voltage and current monitoring BNC outputs
  • Isolated external Vdc reference input to control current remotely
  • 115 or 230 VAC input 150 VA, 3.15A fused, 62 kg weight, 353 × 440 × 589.4 mm

Power envelope curves for 63200 series also available from datasheet:

63204 is main strong-hold is high voltage operation, but we can also study more detailed curve with 63204 specific data in low voltage mode:

According to this plot low-ish load currents around 20A can be reached already at quite low voltages, such as 0.5 VDC.

With typical DC/DC regulator outputs such as 3.3V or 5V maximum 100A load current can be reached.


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Front panel

Mains transformers

Interface boards

Analog front-end board

Cooling system

5200W high-voltage distributed DC load bank module


It was just unplugged cable. After plugging cable back in, everything worked fine :)

Tests and benchmarks



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Author: Ilya Tsemenko
Created: March 2, 2022, 3:05 a.m.
Modified: Feb. 10, 2024, 6:47 p.m.