Disclaimer: I am not responsible for any damages to any equipment caused by following information on this page. Proceed at your own risk!      The Sony VPH-1031Q is a very quiet video projector. However, when it is floor-mounted without a hushbox, the noise made by it's two internal 80mm 28dbA chassis fans can be somewhat distracting during quiet moments of a movie. One option to resolve this issue is to replace the fans with quieter fans. To my knowledge the most quiet 80mm fan is 12dbA and retails for around $18. Another option that has been brought up by AVS Forum members is to disconnect the fans altogether. After all, Sony did make an earlier convection-cooled projector, the VPH-1020Q, which uses the same CRT tubes as the 1031Q and many other 10xx units with exception to the last line of 10xxs which featured with brighter 07MS CRT tubes.      I decided to get a temperature probe and sample the 1031Q's chassis temperature with and without the fans connected. My original plan was to attach the temperature probe to the green CRT tube face. Then I figured that attaching the probe to a metal portion of the tube as opposed to the glass tube face would yield a better representation of not only the tube temperature but also the chassis temperature. I ended up attaching the probe to the metal housing just above the green tube. Since the metal casing around the green tube face is in contact with the metal housing, the metal housing temperature should be somewhat close to the metal CRT tube face casing temperature. In addition, attaching the probe to the metal housing was easier and more stable than attaching it vertically to the CRT tube face metal casing.      Upon attaching the probe I put all of the plastic covers back on the projector to simulate normal conditions. The covers obviously hinder cooling to some extent. Finally, I started up the projector with the fans connected and played a movie. Temperature was measured every 10 minutes. I then let the unit cool down and sit for about 12 hours and repeated the procedure with the fans disconnected. The accuracy of the temperature measurements is ±1°C and the accuracy of the time is less than a second. In addition, the temperature probe only updates its display every 6 seconds.

Results:

These data imply that the internal fans do not significantly cool the chassis. Regardless of the fans, the projector will heat up. It could be extrapolated that since the fans do not play a major role in cooling the chassis, then they don't play a major role in cooling the major source of heat inside the projector - the CRT tubes. Ideally the CRT tube coolant temperatures would have been measured since it is the coolant that is mainly responsible for cooling the CRT phosphors. The two line graphs are not massively divergent from each other. That result seems to imply that running the 1031Q for limited time periods at room temperature or below, within reason, without fans running is reasonably safe. As some people have stated, perhaps the trade-off to running the 1031Q, or any fan-cooled VPH-10xx series projector using SD-187 tubes, without fans is decreased tube and/or chassis life. In any case the data are open to many interpretations.

Pictures: