LeCroy 9424, Quad Channels Oscilloscope

  • Only one ADC card, connected to CH1 and CH2
  • CH1 seems ok, passes tests
  • CH2 have faulty trigger, can't trigger properly and trigger doesn't pass tests and calibration
  • Missing PSU
  • Doesn't have the memory card board
  • Calibration log
    • Trigger Calibration code 33 for CH2
  • Full DC non-linearity analysis : all is within the %
  • According to flow chart of service manual, Trigger Calibration Failure means replacing the 9420-4 TDC (Time Base card)
  • Swapped the Time Base card with a working one from a 9420 and the scope works again.
  • Backplane seems a little bit dirty, sometime false contact
  • Worst case I swap the backplane with a 9420 one
  • 9424 shares parts with 9414 and 9450 or 9420

I got this one without a PSU, so I worked on building a new one.

In the original design, LeCroy used mainframes-like power modules.

The power distribution use a common ground, this new PSU also uses common ground too.

I used MeanWell PSU and a custom 3D-printed frame to hold them.

MeanWell modules:

  • RS-50-5, 5V, 10A, two of them, one for +5V, one for -5V
  • RS-75-15, 15V, 5A, two of them, one for +15V, one for -15V
  • RS-15-12, 12V, 1.3A, only one, used for the fan


The screen needs a locked-to-AC-50Hz signal, I don't have a circuit for that yet so I used an Arduino with the following code:


The only drawback is that, really high speed signal seems to make the screen flickers, but anyway, it works.

I won't upload them here, but they are all available Here, organised as sub-folders in high-res.

  • workbench/lecroy_9424.txt
  • Last modified: 2019/08/27 13:51
  • by dashie