Dreaded white DOT

Sander Spies · August 26th, 2008, 10:46 PM

The thought of selling had crossed my mind too, but I have no idea what other camera to buy instead. Besides I don't think I can afford a new cam at the moment, since I got the GD7 for a reasonably low price and as far as I know there aren't many other cameras in that price range which have the same specs. Anyway, first I'm going to return it again, probably today. Let's see what they tell me this time...

Btw: AGC is Auto Gain Control. My pixels are white too, so like Steve says, it must be something that affects all colors (RGB).

Steve, can you please give us some more info on the "Executing PRESET" you mentiond?

Wayne Avanson · August 27th, 2008, 12:44 AM

Good luck with that Sander.

I took mine in two and a half weeks ago so it shouldn't be far off now. i'm disappointed that no one contacted me re a replacement which is what I was really chasing after.

i suspect they'll just repair it and send it back as before. Useless.

Add to that, my Twoneil lens adapter finally turned up yesterday. So what shall I do with that now? hmm.

Wayne Avanson · September 1st, 2008, 07:59 AM

I got the cam back just now and have set it on test. The people at the shop said they spoke to the service manager at JVC about our concerns regarding warranty running out and ending up with a camera that may or may not need a third repair, and was told that they were VERY surprised to have to repair it again and that this is very rare. They also apparently have a three strikes policy at JVC and if it has to go in a third time, no matter what the warranty situation, it will be replaced.

All sounds very promising. Only time will tell. at least the pressure's off for selling it now. I can keep it and hope it doesn't happen again, and if it does, take them for a new one. Always proving they have a new one to send me.
Avey

Sander Spies · September 9th, 2008, 09:28 AM

Thanks for the update Wayne! Although I still got 7 months warranty, it's good to hear about their "three strikes"-policy. Haven't got mine back yet, but as soon as I do I will test and post the results here!

Wayne Avanson · September 9th, 2008, 09:35 AM

7 days of testing later - (constantly filling the hard drive then checking the footage) - has revealed no new white dots as yet Sander. Just done another session today.

I figured if I am to get a new one if the dots come back, then the sooner they come back the better. (Odd way of looking at it I know but hey…) After all, it WAS six weeks before I got the return of the dots last time.

I was told that JVC had updated the firmware, whereas last time, the chit said updated software. So who knows, maybe that'll make the difference.
Look forward to hearing your results bud.

Steve Mullen · September 9th, 2008, 07:21 PM

Quote:

Originally Posted by Wayne Avanson

I was told that JVC had updated the firmware, whereas last time, the chit said updated software.

They are the same thing -- so they did the same thing twice. But, firmware/software can't go "bad" so their explanation makes NO sense. ZERO!

My GUESS is that they ran software that mapped-out the bad pixels.

Of course, I still can't see HOW three pixels at the same spot on three separate chips could go bad at the same time!

Lets assume a GREEN gets stuck ON. The pixel should range from green to yellow to cyan to magenta as the background varies.

Lets assume a GREEN gets stuck OFF. The pixel should range from red to blue to magenta as the background varies.

Perhaps, the V and H pixel-shift circuit in some weird way makes white when one of any of the nearby pixels goes bad in any way.

If they did map out bad pixels - it should work unless the camera is re-exposed to high heat. Unless, of course, the CCDs are slowly going bad over time. Something I've never heard of.

Wayne Avanson · September 10th, 2008, 01:25 AM

Thanks for the post Steve, most helpful.

You;re right, the pixel didn't change colour, it just stayed white. I admit, things were hot in Turkey and the camera got too hot to touch more than once, but why then would the problem be intermittent?

Of all the footage I brought back, (about four and a half hours worth) less than five percent of it had the white dot . Then, when I ran it on test over and over when I got back, the dot came back when the camera got warm after running for a while, a couple of hours or so.

Surely if a pixel died, that would be it it would be permanently white?

All this means that I can't trust the camera after all and will have to sell it. Poor show!

Max Yeremin · September 10th, 2008, 02:13 AM

These CCD pixels are not dead, they're "hot". A CCD matrix is like an analog shift register - the amplitudes are serially shifted from the cells to the readout. If a cell has a higher than normal leakage, by the time a frame is fully shifted the pixel voltage amplitude drops, and the pixel will look brighter. The leakage is proportional to the temperature, so hot pixels show up after a warm-up. Of course, there are many more hot pixels in your CCD than you think. I once did an experiment - put my HD7 running in the carrying case, and left it there for the night. When I took it out in the morning it was very hot to touch (don't do this at home!). After I closed the lens cover I could see something similar to a christmas tree - dozens of hot pixels all over the image - red, green, blue, white, etc.

It's a very common problem (unfortunately) for all CCD-based devices. Nikon SLR cameras are known for these problems, many Pro systems as well. Pro cameras sometimes use coolers, ice packs, etc.

CMOS sensors don't have the hot pixel issue, because, they not serial devices like CCD.

Wayne Avanson · September 10th, 2008, 02:18 AM

Hey, thanks Max!

So how do I avoid the pixels coming back white? Just simply keep it cool? That's not always possible if I'm filming a play performance or Seminar as the cam has to work in warm environments for a long stretch without a break.

Ice packs then?

Max Yeremin · September 11th, 2008, 01:48 AM

Hi Wayne,

I don't think with a consumer camera you can really do anything. Either live with it, try to have JVC to repair it, or consider a CMOS sensor cam. The problem with the CCDs is that being the delicate analog things, they "evolve" - blemishes can appear with age, due to certain conditions, etc. With CMOS sensors it's a bit easier - either you have a defective pixel or you don't - the defects are mapped-out when the chip is made and stay that way forever.

Steve Mullen · September 11th, 2008, 09:54 AM

Has anybody tried to heal a ccd by putting it in the fridge or even freezer? Perhaps running.

Sander Spies · October 18th, 2008, 04:26 AM

It's back! I haven't done any testing yet, but I will put it on a tripod and let it record for some time today. The workorder said they replaced the prism element (I think that's the element that breaks up the incoming light (image) before it reaches the CCDs(?))

Wayne Avanson · October 18th, 2008, 09:02 AM

The Prism Element eh? Sounds odd.

Keep it running and see how it goes Sander. I ran mine every day for three weeks filled up the drive and then emptied it again. No problems yet. But I haven't been anywhere hot yet either.

Steve Mullen · October 18th, 2008, 07:13 PM

Quote:

Originally Posted by Wayne Avanson

The Prism Element eh? Sounds odd.

Sure does.

Steve Mullen · October 27th, 2008, 12:45 AM

Quote:

Originally Posted by Wayne Avanson

The Prism Element eh? Sounds odd.

AHHH. Prism block includes the 3 CCDs that are glued in place. So it does make sense.

August 27th, 2008, 12:44 AM	#62
Wayne Avanson Major Player Join Date: Feb 2008 Location: Lancashire UK Posts: 496	Good luck with that Sander. I took mine in two and a half weeks ago so it shouldn't be far off now. i'm disappointed that no one contacted me re a replacement which is what I was really chasing after. i suspect they'll just repair it and send it back as before. Useless. Add to that, my Twoneil lens adapter finally turned up yesterday. So what shall I do with that now? hmm. Last edited by Wayne Avanson; August 27th, 2008 at 02:02 AM.

September 11th, 2008, 09:54 AM	#71
Steve Mullen HDV Cinema Join Date: Feb 2003 Location: Las Vegas Posts: 4,007	Has anybody tried to heal a ccd by putting it in the fridge or even freezer? Perhaps running. __________________ Switcher's Quick Guide to the Avid Media Composer >>> http://home.mindspring.com/~d-v-c

August 26th, 2008, 10:46 PM	#61
Sander Spies New Boot Join Date: May 2008 Location: Utrecht, The Netherlands Posts: 15	The thought of selling had crossed my mind too, but I have no idea what other camera to buy instead. Besides I don't think I can afford a new cam at the moment, since I got the GD7 for a reasonably low price and as far as I know there aren't many other cameras in that price range which have the same specs. Anyway, first I'm going to return it again, probably today. Let's see what they tell me this time... Btw: AGC is Auto Gain Control. My pixels are white too, so like Steve says, it must be something that affects all colors (RGB). Steve, can you please give us some more info on the "Executing PRESET" you mentiond?

September 1st, 2008, 07:59 AM	#63
Wayne Avanson Major Player Join Date: Feb 2008 Location: Lancashire UK Posts: 496	I got the cam back just now and have set it on test. The people at the shop said they spoke to the service manager at JVC about our concerns regarding warranty running out and ending up with a camera that may or may not need a third repair, and was told that they were VERY surprised to have to repair it again and that this is very rare. They also apparently have a three strikes policy at JVC and if it has to go in a third time, no matter what the warranty situation, it will be replaced. All sounds very promising. Only time will tell. at least the pressure's off for selling it now. I can keep it and hope it doesn't happen again, and if it does, take them for a new one. Always proving they have a new one to send me. Avey

September 9th, 2008, 09:28 AM	#64
Sander Spies New Boot Join Date: May 2008 Location: Utrecht, The Netherlands Posts: 15	Thanks for the update Wayne! Although I still got 7 months warranty, it's good to hear about their "three strikes"-policy. Haven't got mine back yet, but as soon as I do I will test and post the results here!

September 9th, 2008, 09:35 AM	#65
Wayne Avanson Major Player Join Date: Feb 2008 Location: Lancashire UK Posts: 496	7 days of testing later - (constantly filling the hard drive then checking the footage) - has revealed no new white dots as yet Sander. Just done another session today. I figured if I am to get a new one if the dots come back, then the sooner they come back the better. (Odd way of looking at it I know but hey…) After all, it WAS six weeks before I got the return of the dots last time. I was told that JVC had updated the firmware, whereas last time, the chit said updated software. So who knows, maybe that'll make the difference. Look forward to hearing your results bud.

September 10th, 2008, 01:25 AM	#67
Wayne Avanson Major Player Join Date: Feb 2008 Location: Lancashire UK Posts: 496	Thanks for the post Steve, most helpful. You;re right, the pixel didn't change colour, it just stayed white. I admit, things were hot in Turkey and the camera got too hot to touch more than once, but why then would the problem be intermittent? Of all the footage I brought back, (about four and a half hours worth) less than five percent of it had the white dot . Then, when I ran it on test over and over when I got back, the dot came back when the camera got warm after running for a while, a couple of hours or so. Surely if a pixel died, that would be it it would be permanently white? All this means that I can't trust the camera after all and will have to sell it. Poor show!

September 10th, 2008, 02:13 AM	#68
Max Yeremin Tourist Join Date: Dec 2007 Location: San Jose, CA Posts: 2	These CCD pixels are not dead, they're "hot". A CCD matrix is like an analog shift register - the amplitudes are serially shifted from the cells to the readout. If a cell has a higher than normal leakage, by the time a frame is fully shifted the pixel voltage amplitude drops, and the pixel will look brighter. The leakage is proportional to the temperature, so hot pixels show up after a warm-up. Of course, there are many more hot pixels in your CCD than you think. I once did an experiment - put my HD7 running in the carrying case, and left it there for the night. When I took it out in the morning it was very hot to touch (don't do this at home!). After I closed the lens cover I could see something similar to a christmas tree - dozens of hot pixels all over the image - red, green, blue, white, etc. It's a very common problem (unfortunately) for all CCD-based devices. Nikon SLR cameras are known for these problems, many Pro systems as well. Pro cameras sometimes use coolers, ice packs, etc. CMOS sensors don't have the hot pixel issue, because, they not serial devices like CCD.

September 10th, 2008, 02:18 AM	#69
Wayne Avanson Major Player Join Date: Feb 2008 Location: Lancashire UK Posts: 496	Hey, thanks Max! So how do I avoid the pixels coming back white? Just simply keep it cool? That's not always possible if I'm filming a play performance or Seminar as the cam has to work in warm environments for a long stretch without a break. Ice packs then?

September 11th, 2008, 01:48 AM	#70
Max Yeremin Tourist Join Date: Dec 2007 Location: San Jose, CA Posts: 2	Hi Wayne, I don't think with a consumer camera you can really do anything. Either live with it, try to have JVC to repair it, or consider a CMOS sensor cam. The problem with the CCDs is that being the delicate analog things, they "evolve" - blemishes can appear with age, due to certain conditions, etc. With CMOS sensors it's a bit easier - either you have a defective pixel or you don't - the defects are mapped-out when the chip is made and stay that way forever.

October 18th, 2008, 04:26 AM	#72
Sander Spies New Boot Join Date: May 2008 Location: Utrecht, The Netherlands Posts: 15	It's back! I haven't done any testing yet, but I will put it on a tripod and let it record for some time today. The workorder said they replaced the prism element (I think that's the element that breaks up the incoming light (image) before it reaches the CCDs(?))

October 18th, 2008, 09:02 AM	#73
Wayne Avanson Major Player Join Date: Feb 2008 Location: Lancashire UK Posts: 496	The Prism Element eh? Sounds odd. Keep it running and see how it goes Sander. I ran mine every day for three weeks filled up the drive and then emptied it again. No problems yet. But I haven't been anywhere hot yet either.