Kikusui PLZ 72W electronic load teardown

Today’s quick teardown target is a 1985 vintage electronic load made by Kikusui of Japan. It came from eBay with a noisy fan, but was otherwise fairly functional despite the considerable age.

Only 2 inches wide

Only 2 inches wide

The load offers quite a nice set of features, all without using a microcontroller.

  • Constant current and constant resistance modes
  • 4-110V input  range up to 12A
  • 12A and 1.2A range
  • Two independently settable current levels with pulse ability (1kHz and 100 Hz)
  • Current monitoring output for scope connection

Being purely analog, no serial interfaces are available. Instead the load takes voltage and resistance control signal via terminals on the back. Opening the lid brings us a very tightly packed unit:

Very compact and tightly packed design

Very compact and tightly packed design. Fan removed for replacement

OLYMPUS DIGITAL CAMERA

OLYMPUS DIGITAL CAMERA

Massive heatsink and cables galore

Current sense resistor

Current sense resistor

Thermostat

Power BJT transistors by SanKen are behind this board

Power BJT transistors by SanKen are behind this board

Power BJT

Power BJT

1985 datecodes

1985 datecodes

 

All open wiring, no heatshrink in sight

Input leads soldered straight to screw terminals

Input leads soldered straight to screw terminals

 

Wires everywhere

Wires everywhere

For those interested, user manual is here. The load is very compact and handy, especially for those with small desks. The exposed high voltage leads on the transformer made me want to put a sheet of isolating material on the inside the case opposite of them, just in case. At least the case is grounded…

 

 

 

6 thoughts on “Kikusui PLZ 72W electronic load teardown

    • If my records are correct, I used NMB 2412PS-12W-B30. It’s a a current model,but 115VAC version. It ends up running a bit slower on a 100V transformer winding, but oh well

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