Intro: Led Movie Projector Hack/Mod (runs Cooler and With Less Noise)
I have just bought a projector, it is TP90s with 1280x720p, 3200 lumen and android 4.4. (it's the one in the picture) and by my guess all of the GP90 / TP90 are the same model, just sold by different brands / resellers.
It is a good deal for the price, but once it arrived I have found it had two main problems:
- Super noisy cooling fans (measured at 57dB)
- It spits a constant stream of hot air from it's vents (measured at >45ºC Celsius at the vent).
Well, I decided to get my Swiss army knife and go MacGyver on it. *cue the music*
BEFORE YOU PROCEED / DISCLAIMER
NEVER open or handle the device while it is powered, you can die! Always remove the power cord just to be safe!
Some mild soldering skills are needed for this hack/mod if you are not comfortable do not try it, you can loose the power supply, and it's "game over man, game over".
Step 1: Open Wide and Look Inside
I removed the shell, by unscrewing the 6 screws under the body and gently separating the two halves.
This is what the inside looks like. Not bad!
Since the heat source is the led I plugged my trusty multimeter and measured it's power consumption. It was 3.6A at 29v.
Using ohm's law W = A x V, i got 3.6A x 29v = 104 watts, I also determined the current is constant, so the power supply is set to deliver 3.6A no matter what.
Step 2: Before We Continue, Something About These Power LED's
These new power led's (20w,30w,50w,100w) are not a single chip but instead are build by joining a bunch of smaller led's together. The standard seems to be x parallel rows of 10 leds in series.
Why 10 leds in series you may ask? Well, consider each led needs between 2.5v to 3v of forward voltage to work, so 10 x 3v = 30v (and that is why the power supply i measured in the previous step is outputting 29v).
Each led also needs to have the current that passes through it limited between 20~30ma, because otherwise it will burn out or if you have a big enough heat sink it will warm up your room...
Ah! Ahh! There might be something here!
Step 3: The Game Is Afoot
My dear Watson, consider the facts:
The power supply is a outputting a constant 3.6A (3600mA), and we know each led needs about 30mA to work, so 3600mA / 30mA = 120 leds. If each led is rated 1watt, that gives 120w. Since there aren't any 120W led widely available I decided to look at the led installed and I found the problem!
The led is just 6 rows of 10 leds, so it's a 60w led that is being powered by a 120w driver.
The heat from hell that comes off the projector is because it's wasting 60w of power over the heat sink that is trying to cool the poor led down.
We now have found the cause for the problems, we need to fix it!
Step 4: Easy Fix
After a quick look and some testing I found that the blue trim pot on the power supply that comes in this unit adjusts the current, but unfortunately it only dropped it to 3200mA, which is still way too high for our poor led.
The solution is to remove the existing trim pot and install a 10k one and then adjust it. After i did this i was able to reduce the current down to 1800mA (1.8A), which is the target current for a 50/60w Led. (If you want to reduce the current below 1800mA, just use a 22k trim pot instead of a 10k.)
And.... Happy days, it works!
The led did not loose any brightness, it still shines the same and gives the same lux, but i was able to reduce the power loss and now instead the heat sink reaching 60~70ºC (Celsius) it's now quite happy at 40~50ºC!!!
Step 5: Reaching the Power Supply
To remove the power supply the second cover also needs to be removed.
WAIT A MINUTE!
Did you power the device off and removed the power cord like i said or are you feeling lucky?
I thought so....
Now, remove the screws that hold the pcb in place, then gently peel the piece of tape that holds the display ribbon and flip the black lever part up, so you can slide it off it's socket. To install it back, slide the ribbon into the slot and then push the black lever down.
Detach all cables, and for those with wifi, take care of the antenna cable, it will get loose of it's tinny socket, so if your wifi does not work after this process, double check if the antenna is connected!
Then remove the two screws that hold the LCD in place, and take it out. Keep unscrewing the second cover screws and remove it. Finally unscrew the two holding screws of the power supply and take it out!
P.S. Since you have all optical's in sight now, you can clean them with a clean cloth to remove any dust or particles on the lenses, glass, mirror and LCD display.
Step 6: Now for the Cooling Fans
Because so much heat was generated, high flow, high RPM and high noise fans were factory installed!
Now we don't have the heating problem any more, so we can replace them for new silent ones (low RPM and low air flow) or keep the existing ones but placing a 55 Ohm / 5W resistor in series over the red (+) wire of each of the fans (1 resistor per fan). That will drop the voltage and make them spin half the speed. Half speed = much lower noise.
I was able to reduce the noise from the 50~60dB to 40~50dB using the original fans!
P.S. I used a 5w resistor to ensure that no heat whatsoever was generated by it.
Step 7: The End
With this hack / mod I able to cut the heating and noise in half!
Also the led wont burn out in a few months due to over current and overheat, and will last it's intended live cycle of 20.000H +
I hope this helps!
Btw, if you reached this point i should warn you, there is no tutorial to put everything back together xD