The SEII card in your computer both generates the microscope scanning signals and also receives the video signal for displaying on your screen. This fact lends itself to a particularly simple way to diagnose both the SEII card horizontal/vertical scanning operation and the ADC Channal_A/Channel_B imaging operation. The concept is to route the scan output back into the video input. By imaging the scan ramp, you can prove that both the scanning output function and video input function are performing correctly (or not).

printing this page: Set view to landscape and print at 40%.

Procedure:

Using your favorite connection scheme (we suggest paper clips), disconnect the ribbon cable from the back of the SEII card in the computer and set the ribbon cable aside. Then wire the SEII card rear connector as follows:

to check the horizontal [X] [fast] [line] ramp: to check the vertical [Y] [slow] [frame] ramp:

The SEII generates ±3 volt or ±5 volt ramps (depending on the hardware version) which have now been fed into the video circuit. If your hardware setup windows are set up as shown below, you will see each ramp imaged in the linescan window. The ramps disappear at top and bottom because the ramp signal is larger than the input range of the ADC. Also, since individual linescans are being displayed, the horizontal scan looks "constant" (small jitter is normal). The vertical scan, seen as a straight line here, will actually be "swooping" from bottom to top of your linescan window.

horizontal [X] [fast] [line] scan; Note the ADC-A setting! vertical [Y] [slow] [frame] scan; Note the ADC-B setting!

Going back to the preview window then shows the following:

horizontal [X] [fast] [line] scan vertical [Y] [slow] [frame] scan

If you see this behavior, there is nothing wrong with the scanning circuitry on the SEII card, nor is there anything wrong with the video input. You must look elsewhere for your problems.