Problem lens cap

It could one of a few problems:

1. The viewfinder is pulled out and "PRIORITY" is set to "FINDER".

Push the viewfinder back in or set "PRIORITY" to "LCD".

2. The LCD monitor's brightness setting is too dark.

Adjust the brightness of the LCD monitor.

3. If the monitor is tilted upward 180 degrees, open the monitor fully.

Download the manual for more info:
JVC GR D290 Manual

It's definitely an internal problem in your camera and it sounds like you don't have any warranty after 5 years. I don't have a step-by-step help guide for you since I don't know about this camcorder but in my opinion, if the camcorder is really that good, it's worth the repairs. Though HD camcorders are getting cheaper these days...

It sounds like you may have the the camera in manual mode or that the Iris may be turned down. I am not sure if you model has an Iris control so make sure it is not in manual mode.

You may have lost your image sensor.

1. Take lens cap off.
2. Look in lens make sure there is nothing on or blocking lens.
3. Find bright room & see if image comes up.
4. Make sure your in video record mode.
5. If you have eyepiece lens look to make sure it is off. {Most cams will not let you use both at same time.}
6. Still no image try recording on blank disk then play back see if image is recording.

If that does not work MSG back.

It shows all menus, numbers and graphics on LCD, but seems like there's no picture coming through the lens. In both modes, video and still. It seems like it can not see anything as if the lens cap was on all the time.

Could this be a problem with sensor.. CCDs? Lens? Something else?

If the lcd screen is black even with the lens cap off,the ccd base assy. needs replacing.

there is a repir thing with certain models see below. CCD Failure/Lens Cap Warning Error JVC has received reports that in certain circumstances, the following models may, while in the camera mode, show no picture, a distorted picture and/or display “LENS CAP” even though the lens cap is removed. We have identified the probable cause as a failure of the CCD image sensor. Repairs of units exhibiting these problems as a result of a defect in the CCD image sensor will be made free of charge at a JVC Authorised Service Centre even if the unit is outside warranty.
Please call our Consumer Support Department on 0870-330-5000 to obtain your free repair. We apologise for any inconvenience and we appreciate your understanding and support.
Please note that this offer expires on 30th June 2009 and is applicable only to failure of the CCD image sensor.
This information applies to the following models:
GR-D18, GR-D20, GR-D21, GR-D22, GR-D225, GR-D23, GR-D24, GR-D30, GR-D31, GR-D32, GR-D33, GR-D34, GR-D40, GR-D43, GR-D50, GR-D53, GR-D54, GR-D60, GR-D63, GR-D70, GR-D73, GR-DX25, GR-DX27, GR-DX28, GR-DX35, GR-DX36, GR-DX37, GR-DX45, GR-DX47, GR-DX48, GR-DX55, GR-DX57, GR-DX67, GR-DX75, GR-DX77, GR-DX78, GR-DX95, GR-DX97, GR-FX15, GR-FX16, GR-FXM39, GR-FXM393, GR-FXM40, GR-FXM404, GR-PD1, GR-SX19, GR-SX25, GR-SX26, GR-SXM29, GR-SXM30, GR-SXM49, GR-SXM50, JY-HD10.

PLease see http://www.fixya.com/support/t131881-sony_cam_recorder_wont_record for more information on this i have had the same problem, faulty CCD image processor chip.

Assuming you don't see any video through the viewfinder, it could be that the CCD has died on that camcorder. It happens, though not frequently.

If the video though the viewfinder is clear, there might be some sensor on the lens ring to indicate a lens cap, or an automatic lens cap not properly disengaging when put in record mode. 

Sounds like you may have a problem in the auto iris curcuit or the auto settings was switched to manual and the lens is closed. Check first to see that the lens is setup in auto mode. If it is then the auto iris as i said before is bad or stuck closed unless the small caps in that curcuit went bad as they always do after a few years. Good Luck