JVC PROFESSIONAL PRODUCTS COMPANY



PRODUCT NOTE: DEAD PIXELS






CCD cameras can develop CCD blemishes where a pixel or two can appear white in the image. These may be caused by atmospheric radiation and also by manufacturing impurities that begin to show after years of use.



This is so common on CCD cameras by all manufacturers that we all build into our pro cameras the ability to detect and correct these blemishes.



On the GY-DV5000U camera this process is provided in a Service Menu accessed by holding the FAS and LOLUX buttons in when you press the Menu/Status button.



You see the service menu says CAMERA1. Go ahead and push the shutter wheel to enter that menu and now you have a short list with the forth item being ERROR DETECT. Move down to it and select that item, the word CANCEL blinks. Change it to EXECUTE and push again. It takes about 10 seconds or so to perform the operation and then tells you to power off the camera. You are done. Make sure FAS and LOLUX are now OFF.



However there are a fews things for you to note about this process:

1. The process only conceals blemishes that show at 0db of gain. Blemishes that show at 6db, 9db or 18db will not be corrected. Also there is a threshold that the blemish must be above to be detected. Over time those blemishes may become greater and then show at 0db and then will conceal.

2. Because of a good reason that would take too long to explain, the process can “miss” a blemish. It is absolutely likely that you might have to run the procedure a few times to find the blemish and conceal it.

3. Warming the camera makes the blemishes brighter and easier to correct. Some people wrap the camera in a blanket or coat to help warm it up. We do not recommend warming your GY-DV5000U in a microwave oven.

__________________
Lou Bruno
MODERATOR

JVC Professional Products Company
Product Note
Date - August 22, 2003
Wrom: TQTIPWIGYO
Subject :Removing a Stuck Tape


This procedure can result in damage to your camera if done carelessly.

1. The dual cassette size mechanism introduced in late 2002 in the GY-DV5000U, BR-DV3000U, and BR-DV6000U products provides a method of removing a tape cassette if it is stuck inside due to a malfunction/failure.

You need a medium sized Phillips screwdriver.

It is necessary to remove the cassette side cover of the camera (the side with the video output connectors). This must be done carefully to prevent damage. Open the cassette door and then loosen the 4 screws holding the side cover. Lay the camera on a table with the cassette side up and the handle towards you. You can now look right down onto the mechanism.

2. There are three things you want to do. First get the tape back into the cassette. Second, retract the loaded tension arms. And Third, eject the cassette.

* First, To pull the tape into the cassette you turn a red screw. It is hard to see. With the mechanism facing up and the handle towards you. The screw is actually closer to you than the cassette’s outer edge (where the label goes). Look down in the middle just closer to you than the edge of the cassette. A flashlight will help. There is a flat red screw down in the base plate of the mechanism. Turn it one way and the tape gets tighter.
* Second, Now there is a red gear (one of two) that is toward the front and bottom of the mechanism. It has an arrow in the metal near it and it turns left and right as you have the camera now. Push down and turn the gear many times in the direction of the arrow. The tension arms will retract. This will make the tape loose so go back and turn the tape screw above. There will be a time when the gear no longer turns and the tape is all back into the cassette.
* Third, Now the other red gear can be turned in the direction of its arrow and the cassette will move up and out. You need to have the tape all the way into the cassette since the cassette will now be covering the red screw.

Now you want to know, what to do with a camera that you just had to take the cassette out of the hard way. Do you try the cassette again? You can do this as many times as you like but it isn’t going to fix anything. It is likely the camera now needs to go to be serviced.

It is very rare that some momentary “glitch” happens where you manually remove the cassette and the camera is then fine.

But you did get the tape out.

__________________
Lou Bruno
MODERATOR

JVC PROFESSIONAL PRODUCTS COMPANY



PRODUCT NOTE


Menu items:

Video versus frame mode:

This is actually “field integration” versus “frame integration” modes of CCD scanning.



In “video or field” mode the CCDs are allowed to charge for 1/60th second and then their information is tranfered out and they start to charge again for the next 1/60th second. Also we sum two rows of pixels for each line of the image. For field 1 we use row 1 and 2 aded together to make line 1. Also we use rows 3 and 4 added together to make line 3. For field 2 we use rows 2 and 3 added together to make line 2 and also row 4 added with row 5 to make line 4. And so on down the chip. The adding of the lines together gathers more light but doesn’t decrease vertical resolution as much as you would think. So if field integration you have vertical resolution of about 380, more light sentitivity, and less “jaggies” as the lines get added together.



The “frame integration” is the mode that many think of. For field 1 we charge and read row 1 to be line 1 and row 3 to be line 3 etc. Then for filed 2 we charge and read row 2 to be line 2, row 4 to be line 4 etc on doen the chips. This has higher vertical resolution, lower sentitivity, and can show a bit more “jaggies”.





Slow shutter:

The camera can be operated with a “shutter” speed of 1/30, 1/15, and 1/7,5 second. Of course video cameras don’t actually have shutters and must still send a field image to be recorded every 1/60th second.



So the camera basically “holds” the image and then outputs that image as needed by the VTR timing. For example, a shutter speed of 1/15 second means that each of the 15 images in a second must have 4 fields recorded on the tape. So the image reads to a buffer every other second and that stored image is then recorded four times. So the image will have this stutter type motion.



The other aspect of this slow shutter is that the CCDs also charge longer. With a shutter of 1/15th the CCDs actually charge four times as long so more light is gathered.



Notice something here – At 1/30th of a second slow shutter the CCDs charge for 1/30th second instead of 1/60th, so the image tends to be a bit more blurred where there is motion. But he buffer builds the whole frame and then the frame is recorded out as a field at a time, but the fields don’t have the characteristic of a moving object being in one place during field 1 and another place during field 2 because the frame integrated together. This will be very similar to a progressive scan although not exactly the entire top to bottom 1/60th second scan that some may desire.

__________________
Lou Bruno
MODERATOR