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Jvc hd750 picture flicker

marty1

Established Member
I am not having much luck with my pj, within 10 months of owning one it had to be replaced as the image block had gone (something like that) so they give me a brand new one, 6 months on now I am getting a really annoying flickering on the screen, it is faint but noticeable, especially in bright scenes.

I looked through the menu and played about and changed lamp power from normal to high, presto! it seems to have stopped it, for now at least.

I still see the odd little flicker here and there but I am worried that there maybe another fault brewing, can anyone tell me what is going on?

Lamp time is on 1300hrs at the moment.

I would really appreciate your help :lease:

Thanks in advance
 

kbfern

Distinguished Member
The usual cause of lamp flicker is a gradual build up on the electrode whilst running, it can usually be got rid of by running in high power mode for a few hours (10-30hrs) before returning to eco mode.

I found this explanation below by Gary Lightfoot (thanks Gary) which explains better why lamps can flicker.

"UHP lamps are arc lamps rather than filament lamps like we have in our light bulbs at home, so the current has to arc across two electrodes to produce light rather than heat up a filament. Usually the point of least resistance means there is one arc point on each electrode, but sometimes as the arc point wears, another area on the electrode can offer similar resistance so the arc jumps across to there, and then back again, so you get flicker. Putting the lamp on high allows more current to flow and that can make one arc point more conductive (whichever offers least resistance to conductivity) so the lamp flicker goes. As the arc burns in that electrode, the new arc point becomes the point of least resistance so going back to low means the same arc points remain in use."
 
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kbfern

Distinguished Member
Quite true:D
 

marty1

Established Member
Or in the cases of the infamous Panasonic 100 and 200, having completely crap optical blocks.:D

The optical block was what went wrong before and as it was too expensive to repair they gave me a brand new machine, so does this mean the 750 has another dodgy optical block that will need replacing?

Or like I was advised just running it at full power for 10-30 hrs be all that is needed?
 

IAN P

Distinguished Member
The optical block was what went wrong before and as it was too expensive to repair they gave me a brand new machine, so does this mean the 750 has another dodgy optical block that will need replacing?

Or like I was advised just running it at full power for 10-30 hrs be all that is needed?


No harm in trying the "full power" test.

On the Panny it was the firmware, iris, optical block and colour conformity that were fixed. 3 trips to Wales.


I hope it's only the 30 minutes run-in that you need.:)
 

marty1

Established Member
No harm in trying the "full power" test.

On the Panny it was the firmware, iris, optical block and colour conformity that were fixed. 3 trips to Wales.


I hope it's only the 30 minutes run-in that you need.:)

I hope so too, I was distressed last time they took it in as they could not supply me with a replacement pj, so no tv for 3 weeks :eek:

Thanks all :thumbsup:
 

marty1

Established Member
I spoke to JVC who adised the same thing, switch it on high for 30hrs, it didn't work so jvc said I have to buy a new lamp as there warranty only covers 1000hrs of lamp life, is this right as I have only bought this pj just over a year ago now and have 1300hrs of lamp life used, I would have thought if it is a faulty lamp surely they are obliged to repair or replace it?
 

T0M

Established Member
Just a thought but is this a constant problem or just a recent (last viewing) observation? Local electrical company was doing some work in my village before Christmas and on the day my HD1 was flickering - since then nothing.

I think you will be hard pressed to get a replacement lamp FOC as it's outside of warranty - JVC are good to customers but not that good.

Of course if you could find someone else nearby with the same PJ they might let you pop your lamp in theirs to narrow down the cause before you go and spend a fair few bob on a lamp.
 

marty1

Established Member
No it is an ongoing problem, they clearly recognised the problem as they suggested doing exactly what others have suggested on this thread.

Since it has gone over 1000hrs they are not going to fix it or replace it.

If it is a fault and not something that is caused by wear and tear then I do think it is a bit naughty not to fix or replace it. The sale of goods act makes sure that any expensive item that develops faults within the first 6 years of purchase as long as it is a manufacturing fault and not wear and tear. If this is a manufacturing fault then they are in the wrong.
 

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