Quiet Down the Jet Engine, Please.

The 1272 has a GREAT picture. The fans sound like a small jet turbine above your head.
I found some great ideas on AVS Forum for dealing with the fan noise. I've noted the various methods below.
I chose to replace the fans. Unfortunately digi-key has been out of the fan with the rotor lock option for quite a while.
I ordered 5 FBA08A12M1 fans. These are medium speed, but lack the third lead..
I also ordered 10 1watt 5.1v zener diodes. (There's a price break at 10)
I cut pigtails off the old fans, and shorted the yellow and black leads together.
As below, I put the diode inline on the red(+) fan lead with the stripe/cathode towards the connector.
When I finished swapping all the fans, one was pretty loud. I checked the voltage and found that I'd installed the diode backwards.

The pj is now FAR quieter, tho I may reverse the airflow of the two bottom-most fans. The noise level directly below the pj is a bit louder than I like.

From AVSForum.com

I recently quieted the fans on my 1272Q. I took a slightly different approach than the normal fan mod however. Here what I did for anyone that's interested...

First, I ordered up a new set of fans. For the 5 80mm fans, I ordered Panasonic part# FBA08A12M1BS (P11038-ND from Digi-key). These fans have all around better specs than the stock fans (power, airflow, and noise). They also have the locked rotor output, same as the stock fans, so there's no need to disable the stopped fan protection on the projector. For the 40mm fan, I ordered Sunon part# KD1204PFS3 H (259-1200-ND from Digi-key). It's not a significantly better fan than the stock one, but I just figured it can't hurt to have all new fans.

These motors come without a connector, so I cut the connectors off of the old fans and attached them (using solder and heatshrink tubing) to the new fans. Just changing the fans quieted the projector some, but it still wasn't as quiet as I wanted. So, I started dropping the fan voltage to see what kind of effect it had. I must say, the effect is dramatic! There seems to be a magical point where the fan noise all but disappears. Well, maybe I'm exaggerating with the word disappear, but there is a point at which the fan noise really starts to drops fast. With these fans, the magic voltage is about 9-10 Volts (normally, the voltage is about 12.5 volts). NOTE: this only applies to the 80mm fans, I haven't played with the 40mm fan yet.

Anyway, I ended up putting a 5.1 volt, 2 watt Zener diode in series with each 80mm fan to obtain about 8.7 volts at the fan. Yes, I know that 12.5V minus 5.1V is not 8.7V, but there is also a 33 ohm resistor in series with each fan on the circuit boards. The diodes are mounted in the red wire of each fan with the cathode (the end of the diode with the line on it) toward the connector. It would also be possible to drop the voltage right on the boards by changing out the 33 ohm resistors for a larger value, but I didn't feel like removing the boards to change out the resistors. The stopped fan protection still works perfectly and since these motors are rated to operate down to 7 Volts, there's no need for the Chuck Williams fan mod circuit to apply different start and run voltages.

The end result is amazing! The airflow still seems more than adequate, but the projector is now quieter than my old 1031Q.
Sony Fan Mod

This circuit is a series pass transistor voltage regulator circuit to lower the fan voltage to roughly 8.5 volts. This transistor is fully turned on momentarily on power up by a transistor that opens the base circuit of this fan voltage regulator to ensure that the fans start up normally. A timer circuit that is set up as a one shot monostable controls the circuit. This ensures that the circuit will always act the same way no matter how many times the power is turned off or on.
To install it, cut the black wires from all of the fans (except the tiny one on the heat sink on the E and DC boards, it doesn't make much noise) at their connectors and connect them to the emitter of the 2SB633 transistor (use any PNP power transistor that can deliver about 10 watts in a TO220 package). Be sure to include the two fans from the power supply unit. Connect the collector of the 2SB633 through a 3 amp fuse to -15volts (connector E2, pin 9 should be convenient). Connect the input to the 7805 regulator to +15 volts (E2 pin 6) trough a 1 amp fuse.
On the power supply, you must also disable the fan protect circuit for the power supply fans. The easiest way to disable the fan protect circuitry for the power supply is to cut the yellow wire from each power supply fan about 2 inches from the connector plug and join it to the pin that had the black wire going to it. This means you have tied pins 1 and 2 together of CN254 and CN255 (on VPH1270, 1271, 1251, but probably 1272 and 1252 also). Once you've done this, the fan noise reduction will be absolutely stunning, and there will, IMO, be plenty of air circulating in the unit. Mount the board in a convenient spot, and you're done.
No, what I was saying was that the stock fans in a projector are pretty quiet by themselves (try running one outside of the projector, they are pretty quiet), but the rush of air through the case causes turbulence, which in turn causes noise. I solved that problem by dropping the fan voltage by .7 volts (with a zener diode), which reduces the airflow noise siginificantly without tripping the locked rotor sensor in the fan. Once this mod is done, the projector I modded was so quiet you had to listen for the sound of it running. The thermodynamic change inside the case after this mod was nominal. You really could do this mod to the stock fans in the set, but I replaced the fans because I didn't know the condition of the originals. ---another post down..--- Most of the fan mods I have seen have involved some kind of control circuit to slow down the fans after starting up. This is simply lessening the voltage to the fan so it doesn't run at max, but doesn't know the difference. The zener I used was a 5.1V 5% 2W that I tend to have around the shop. It is more than a .7V drop as I said before, but it worked wonders for the noise problem. __________________ Keith