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:

1. Super noisy cooling fans (measured at 57dB)
2. 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

Comments

[neelis333]

I have same projector and all of a sudden one day the the projector became dim. I did open the project and did not find any burn sign either on LED Chip or power supply unit. Though I say a scratch mark on led chip ( i don't think that might be the reason for dim light) . Can you help me with this. I am not an electrician but surely a have interest and can handle few tests on electricity board.

[Kil]

Hi. I have the same problem. Did you get a solution?

[Jake Joris]

My projector's LED runs at 23.5v 1.9a and the projector gets very hot. The led should be a 60w one, so I don't think that the PSU is overpowering it. Tried lowering fan voltage using a step down regulator to 10v, and it's quieter, but it gets even hotter. I don't have a thermometer, but I think the heatsink reaches at least 60'c within a minute. Might try to access the LED and see if it's really a 60w one.

[SimonH181]

A good idea that will make everything last longer for sure, even if the image brightness is compromised a little. However, unlike domestic security type cob lamps (which are rated 1W per individual chip), projector type cob led's are typically 3W per chip, limited to 2W because of heat dissipation issues (the chips are basically too close together to drive at 3W each!). The 6 x 10 array would be 120W capable, so if anything is a little underdriven at 104W. However, what these cob leds can suffer with is imbalance issues, in that all chips don't light evenly when tested at very low loading with a variable voltage supply. This leads to early failure and a lot of waste heat when driven hard. To get a quality cob chip can be hard to find.

[AndréK59]

Considering your analysis, it should be possible to change the LED from 60w to 100w, and still reducing fan RPM, or even use a 120w, with the same power source.
Would this damage the LCD or any other part of the Projector?
Would be necessary to change anything else to make this happen?
Congrats for the very good job!

[OculumForamen]

This is how companies make money. Society has been one of a "throw it away, when it breaks and go buy a new one" Mentality for some time. The best way to combat this is to return the item for a new one, but it seems that people can't be bothered to keep the model they bought; nor are they happy to spend the time doing it, but they don't mind spending more money to but a new model! The company that makes these things is at a bit of a impasse. They have to use decent quality products, but they don't want their item to last that long in their business model, so they use good quality components, but then they do this kind of thing. They increase the power to the led but run the fans at max to keep it cool, because they know that as their life goes on, they will eventually slow down and the LED will burn out. This is what we call Engineered Obsolescence, and it is the business model of many many companies! Thank Goodness that there are people like you, nume1977, who can trace electronic circuts and understand what is going on inside, and make improvements to it, thereby defeating the incorporated Failures built into the system. I am not under any illusions, if a recular citizen can trace an easy problem with something like this projector, that this company is guilty of only making a mistake. No way, the did it deliberately! Thank you nume1977! do you have a blog or vlog that you normally do on you tube if so I'd like to subscribe to it!

[brian32768]

Great fix but you will no longer be able to use it to warm cups of tea!

It seems like they overspent on heatsinks and fans due to a mistake in the power supply. I don't think they would intentionally do this to shorten the lifespan of the LED.

If profit was the motivation then instead of too much power + oversized cooling system, using a smaller power supply and putting in an UNDERsized cooling system would have saved on manufacturing costs AND shortened the LED lifespan at the same time!! But one should never try to outguess what might have just been poor decisions!

[JAMESM466]

Excellent Instructable. You'd think that by designing these better, they'd have happier customers. I can't see how the mods you did, if incorporated into the manufacturing process, would raise the cost by a cent.

Quieter, longer lasting projector? Who wouldn't want that? (OK, so it'll kill the replacement cycle)

[nume1977]

Before posting this mod i contacted the seller with all this information, so they could reach the manufacturer and at least alert them to this problem/solution. I hope the designers and engineers that come up with these neat products learn something so we (the consumer) can benefit in the future.

[rickharris]

Ah but if the LED burns out in say 2 years of use most people are going to go out and buy a NEW projector. Happy days. (if a little short sighted).

[nume1977]

True, but in 2 years i hope there are cheap 4k projectors already :)

[Swansong]

That's a neat fix :)