March 05, 2009

Multiscan Projector

Multiscan Projector VPH-1252QM by SONY...

That's it! The 'oldies' SONY video projector back in early 90's. This is the kind of projector I use in my office.

It's a CRT (Cathode Ray Tube) Projector, which means, it has 3 small, high-brightness CRTs as the image generating elements. The image is then focused and enlarged onto a screen using a lens kept in front of the CRTs' face. The 3 CRTs are the Red, Green and Blue.The red, green and blue portions of the incoming video signal are processed and sent to the respective CRTs whose images are focused by their lenses to achieve the overall picture on the screen.

Those CRTs have a long service life up to 10,000 hours. Some even says it's up to 20,000 hours. This projector has a superior black level compared to LCD or DLP based projectors, which means, it can produce the blackest blacks of all projector types as well as the full range of color, giving a CRT projector the ability to project the most film-like images of projectors for home use. But CRT Projector is, typically, very large and is not as bright as other types of video projector. So the ability to have a completely dark room is necessary.

Back to this Sony VPH-1252QM, it produces picture with resolution of 1500 x 1200 pixels. It has light output as well as 700 lumen, and On-screen display, which will display adjustment instructions and indications on the screen. This VPH-1252QM also has 4 color systems avalaible i.e. NTSC, PAL, SECAM and NTSC 4.43, which can be selected automatically. In my office, this projector is installed in the opposite direction towards the screen, so a mirror is needed to reflect its light.
I have been operating this projector for 4 years, and I still find it difficult to set up and adjust the projector. It is easier for me to do adjustment with the LCD or DLP based projector. Since the CRT projector houses three projection tubes (red, green, and blue), the tubes need to be aligned so that the projected image does not exhibit color halos and the colors are mixed correctly. Also, if one projection tube fails, all three have to be replaced in order to provide the correct color and brightness balance. In order to set up this projector, I have to do the cross-hair test. This is some sort of test to set up the image produced by this VPH-1252QM. In this adjustment mode, the built-in cross-hair test pattern will be displayed on the screen. If you take a good look at this pattern, there are 3 kind of lines i.e. green line, blue line and red line. All you have to do is to move those lines until they converge to each other and are seen as a white line. If you can't converge those lines, color halos will appear in the picture. It's kinda complicated, you know...because it's hard to see whether the lines are converged or not. Color Halos is like a shadow around the line. It shows up because those 3 colored (RedGreenBlue) lines are not converged perfectly.
FYI, on 2005 we had it changed its 3 CRTs , and one tube cost $600.That means we had to pay $1,800 for the tubes only. Pretty expensive, huh? Sometimes I wonder why it still remains on its service until now. Anyway, we still use this projector to display movies. And when we do this, we need to dim the roomlights. While to display presentation etc., we use an LCD based projector.


  1. Yeppp...that's is expensive. I'd rather choose the LCD or DLP based projector. Anyway,it's great to see one of those ol' things still in service until now....great job, SONY!