Troubleshooting Current Designs Systems

This guide is intended to help you diagnose problems and determine which parts of the system, if any, are in need of repair. We will add to it over time.

The Quick Bundle Check: QBC

Sometimes a response device will work correctly when connected directly to the interface unit, but won't work if connected through the long optical extension bundle. This implies there is something wrong with the extension bundle. But in our experience this is usually not the cause of the issue because the extension bundles are quite robust and don't experience a lot of rough handling in most centers. More often it is the response device which has deteriorated in performance, causing increased optical insertion losses which are masked when the device is connected directly.

To help diagnose this we recommend doing a 'QBC' Quick Bundle Check:

• Hold the two connectors so that one is pointing towards a window or other diffuse bright light source, and the other is pointing towards you
• Check that you see 12 roughly even spots of light
• Move your finger in front of the 'bright' connector and note that you can see dark spots as the fibers are blocked

This is obviously a subjective test but if you see this kind of behavior your extension bundle is probably fine.

The Quick Handheld Check: QHC

For response devices with 4 buttons you can check the basic function by just looking into the connector and pressing the buttons, but there is a trick: light has to be entering the connector. So if you hold the connector very close to you eye it will be very hard to see anything -- no light will come out because none is entering.

• Point the connector towards a diffuse light source roughly behind you and over your shoulder,
• Look for pairs of pins to be bright or dark as you press the buttons
• The specific pins will be different for different model numbers
• This test does not work well with more complex devices

Again, this is a subjective test. When you expand this video to full screen it is more clear than it will probably be when you do it yourself in the lab. But if you're able to see pairs of pins going dark/bright your response device is probably fine. This test may help you confirm that a particular button is not working.

932 Interface Gains

If you are using an FIU-932 interface, and..

If you change configurations (swap response devices, add or remove an extension bundle, etc), then...

• you must re-select the operating mode on the 932 interface so that it can determine the correct gains for the connected devices.

904/905 Interface Gains

If you are using an FIU-904 or FIU-905 interface, and...

If you change configurations (swap response devices, add or remove an extension bundle, etc), then...

• you must disconnect and re-connect the USB cable after making the changes so that the interface can determine the correct gains for the connected devices.

-- BenDugan - 10 Jun 2022