Screen is blue in colour though still has picture. Have changed bulb but it was one left with projector when we purchased house so unsure if new/used. Have read other blogs and they say LCD faulty - would that be the case with this model - Hitachi CP-SX5600W?

chech vga cable

Try turning colour correction OFF. (button in up position). See what affect the iris control has. This control will changed the color of the slide from deep red at nearly closed to washed-out blue and white. at full open. I adjust the controls for each slide. The color temperature of the 8549 lamp varies with the brightness. lower level warmer, higher cooler.

you have at least 2 issues with your optical engine. both are due to excessive dust and heat. the fly-eye (diffuser) lens is fried, as is the light filter on one of the lcd panels. unfortunately, you cannot purchase individual parts for the optical engine. you'll have to replace the whole thing.

IN THE MENU CHECK FOR A COLOR CONVERSION OPTION ,,USE IT ,,TO REALIGN THE COLORS

two problems .out of that any one will solve the problem. the bulb or the colour wheel any out of that has to be checked and replaced.
how to replace the colour wheel with diagram and procedure
http://www.jangro.com/a/2006/07/24/samsung-dlp-replace-color-wheel/

how to replace the lamp in 5 minutes with diagram and procedure
http://www.jangro.com/a/2006/08/03/how-to-change-your-samsung-dlp-lamp-in-5-minutes

On the "Option" menu, try selecting "Service" and the "Factory Reset". This may help. If not, you will have to use the menus to manually adjust the level of blue in the projectin. Go here for the manual for your Hitachi and you will find instructions:
http://www.aboutprojectors.com/pdf/hitachi-cp-x445-manual.pdf

I have a similar issue with yellow pattern on the left and top right of my screen. Took it apart and found the blue lcd had damage that matched the yellow area that was projected. I thought it was the lens but it was the blue lcd .It has gone bad and no replacement. Are you interested in selling the bulb or the whole projector? I have since purchased another projector and am keeping the bad one for spare parts. Hope this helps..Ben
[email protected]..

Can you connect a computer (vga) signal to this projector? I'd like to know what your "white" computer screen does on the projector....example, Excel spreadsheet....

I am leaning towards these problems, a bad video card...or worse delamination of one of your LCD panels and possible polarizer burn in the optical engine.

Best Regards,
Steve

the filter on your projector has gone bad the same needs to be replacerd

Check to be sure that the projector is in the correct mode. If it is expecting an RGB signal and you send it (Y,Pr,Pb), you will see the picture as you describe. The same works for the above reversed. In all likelyhood, you are sending RGB and the projector is expecting the other.
Dan