Projector with a colour cast - probably not the bulb?

[Stuart91]

I've just been trying to troubleshoot a projector for a customer. 

It's a Panasonic unit, 5000 lumens, UXGA res, and only a few years old. It seems to have developed a colour cast over much of the image. Essentially a lack of blue, so white comes out looking yellow. 

This doesn't occur over the entire image, roughly the top right quarter looks acceptable whilst the rest is way off. The customers were convinced that all it needs is a new bulb, I'm more inclined to think that the LCD panel is away and all a fresh bulb would do is present the same problem fractionally brighter. 

I've tried to get in touch with Panasonic support, who don't seem to offer any telephone support any more. Customers are in a rush due to an upcoming event. 

I think I'm correct in advising them that either a repair or new projector is required, and a fresh bulb would be a waste of money. But I'm not 100% sure, is anyone aware of some quirk or optics or specific bulb fault that could cause this kind of problem?

[Jivemaster]

Has the unit been relamped recently? Uneven illumination always says "lamp alignment" to me. Been dropped? Relamped without realignment? Relamped with a dodgy lamp? heat filters lost during relamping or simply cracked or missing?

Edited April 21, 2022 by Jivemaster
spling

[david.elsbury]

I too would suspect a damaged or burnt LCD module

[dosxuk]

If it's not the whole image with the weird colouring, then that generally rules out the lamp. In my experience those symptoms would immediately suggest the LCD panel is on its way out.

[Stuart91]

Thanks, everyone. 

6 hours ago, Jivemaster said:

Has the unit been relamped recently? Uneven illumination always says "lamp alignment" to me. Been dropped? Relamped without realignment? Relamped with a dodgy lamp? heat filters lost during relamping or simply cracked or missing?

As far as I can see, the projector is still on its original lamp. It's at ~1200hrs out of a rated 4000. The projector is hanging from a ceiling bracket, and whilst I can't rule out that it's been smacked by a football at some point, it doesn't seem to have had a hard life. The picture was still perfectly lined up on the screen, so I don't think it's been knocked recently. 

One thing I'm not sure of is what happened during lockdown, e.g. if the building was mothballed and left cold/damp for months on end.

 

I managed to find a support number for Panasonic (they're listed here , the old UK number no longer works). Awaiting a definitive reply from them, but their first impression was that it wouldn't be the bulb. I think we have a consensus emerging...

[dmxlights]

How are you get the signal to the projector. I have seen a odd fault with VGA cable and which was causing a odd mist just like what your where saying this was on half of the projected image. The 10 meter vga cable turned out to be faulty this was fixed from a wall plate to the projector and there was a short 2 meter one from laptop/pc to wall plate was fine

[Stuart91]

1 minute ago, dmxlights said:

How are you get the signal to the projector. 

That's a good thought, Tony. I've come across similar problems with VGA in the past, although usually affecting the whole image. 

However I can see the same problem using the projector's built-in test patterns. (A bit easier to narrow down the problem using a laptop though, as you can compare the projected colours with what it's meant to look like)

[dmxlights]

1 minute ago, Stuart91 said:

That's a good thought, Tony. I've come across similar problems with VGA in the past, although usually affecting the whole image. 

However I can see the same problem using the projector's built-in test patterns. (A bit easier to narrow down the problem using a laptop though, as you can compare the projected colours with what it's meant to look like)

Bummer it looks like the lcd module in the projector has had it then.

The vga cable that I found had a fault on vertical or horizontal I can't remember as it was about 4 years ago. I know it was an odd one for sure

[PJG]

We used to use a model of projector (not Panasonic) which would develop a odd dark tint on parts of the image. While looking at the problem we found if we moved the projector the tint sometimes moved. On opening the projectors we found that the adhesive (it was like grout) was giving up allowing one of the lenses to move very slightly with in its holder. 

[Stuart91]

3 hours ago, PJG said:

We used to use a model of projector (not Panasonic) which would develop a odd dark tint on parts of the image. While looking at the problem we found if we moved the projector the tint sometimes moved. On opening the projectors we found that the adhesive (it was like grout) was giving up allowing one of the lenses to move very slightly with in its holder. 

That's interesting, thanks. The projector is in a mount, high enough up that I've not physically got to it yet but I'll try moving it around just in case that's the cause. 

Did your tint affect the colour, or was it just the overall brightness that changed?