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).

The procedure here is almost identical to that for checking the SEII card by itself. You must read that procedure first, as it contains crucial information not presented here.

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Procedure:

Make sure that the ribbon cable from the back of the SEII card (in the computer) to the Scanning Interface Unit (SIU) is connected and seated firmly on both ends. Make sure that the SIU is powered. Disconnect the Scanning I/O B cable (that goes to the microscope) from the back of the SIU. Using your favorite connection scheme (we suggest paper clips), wire the SIU rear-panel Scanning I/O B 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 are sent to the SIU via the ribbon cable. The SIU then applies a gain and offset to the signals so they will properly drive your microscope. If your hardware setup windows are set up as shown for the SEII card alone, you will see each ramp imaged in the linescan window.

Critical Note: it is possible that your microscope requires signals which are not commensurate with the input range of the ADC. In principal, the signals will look similar to what you see when you are testing the SEII card by itself, but this is not to be generally expected.

LIkewise, when returning to the preview window, you should see something similar to that shown for the SEII card by itself, but this is again not guaranteed.

Given the above caveat, if you see the proper behavior, there is nothing wrong with either the scanning circuitry or the video input on either the SEII card or in the SIU. You must look elsewhere for your problems.