Intro: Fooling the Projector
I will try to give you a general idea how to fool the projector that was designed to squeeze some extra $$ out of your pocket. I will illustrate it with the pictures taken while I was fixing a certain projector but this model is rare and the idea I want to share with you is general. Sorry, it's not a real 'instructable'. I can't name the exact steps for your particular projector but the ideology will remain the same for any case.
Disclaimer - you are going to work with the device that has several dangerous components:
circuit board with live terminals, high-voltage power supply unit, pressurized lamp that can blow up if not handled properly. Think twice and take corresponding precautionary measures to avoid injuries and death :)
P.S. As you can see from the comments in some cases the old lamp may blow up.
I never faced with that myself and the bulb in my friend's projection TV is more
than 10,000 hours old but this "statistics" is not enough so "forewarned is forearmed".
The safest (and most expensive) way to avoid this problem is ... to buy a new lamp but this
defies the purpose of this very instructable. The compromise is to study the construction
around the lamp and if it looks weak then one can install a metal mesh screen.
The design is up to you - it should have fine openings and at the same time it should
not hinder the cooling.
Step 1: General Ideas
Let's assume that you own a projector that says that its lamp is to be replaced.
There can be two reasons for lamp replacement:
1) The lamp really doesn't work because the electrodes are damaged or there was a leak and
the gas inside the lamp has mixed with air or the lamp has blown. These are the real reasons
and of course one has to put some light source instead of the one that got damaged.
Instructables.com is full of various recipes for that. Surely, one can buy the original lamp for
$250-300 but it seems to be a bit overpriced comparing with a projector's cost :)
If you decide to follow one of the instructions from this site briefly read what is written
on the page "Bypassing the control module - 1" below. This will help you to use any light source
while the projector will keep thinking that a new lamp was installed.
2) The lamp is NOT damaged. It's the projector that thinks it needs to be replaced.
Moreover, it tries to convince you. If you remove the lamp and re-install it, it won't start. "How does it know that the lamp is old? May be it's really worn out?", you think and go to the store. Read the following pages to find out the truth :)
Step 2: Bypassing the Control Module - 1
In both cases described above the projector won't start since it somehow knows that
we try to fool it either by inserting a "wrong" lamp or by re-installing the old one.
How it can be? I can imagine two scenarios.
a) The hi-voltage module tries to ignite the
lamp, measures the current, compares with a certain value and produces logical "1" or logical "0"
on one of its outputs. The main board recognizes the signal and doesn't start. In this case one has to identify the signal wire that leaves the hi-voltage module and goes to the main circuit board. ATTENTION: the high-voltage wires are dangerous. You can easily tell them from the signal ones by the insulation type - it's thick and "different" (see the pictures: the white hi-voltage wires are definitely thicker than black and red power wires). This very projector doesn't have a signal wire that goes from the lamp power supply unit but some others do.
If you can identify this wire, try to figure out the logical voltages in your projector. Use a
voltmeter to test the voltages at some logical IC (find the one on the main board not on the hi-voltage board), search the Web for IC by its type and read about the voltages. Usually it is 0/+5V but double check that. Once the wire is identified one has to put the corresponding voltage to this wire to make the projector think that everything works as designed. Check the voltage on this wire with the voltmeter. If it is grounded, cut the wire and put +5V (assuming this is the logical "1" in your system).
If it is at "+5V", cut it and ground it.
Step 3: Bypassing the Control Module - 2
b) Imagine that the high-voltage power supply unit is not that sophisticated and it can't tell a working lamp from a non-working one. It always produces high voltage and goes through the same ignition
cycle once the Power ON button is depressed. Imagine also that the lamp is still operable but you can't
use the projector since 2000hrs have passed. You want to re-set the lamp counter but one has to
see something on the screen in order to do that (there's a corresponding menu item). It looks like a vicious circle.
The trick is that some manufacturers add a small (0.1A in the current case) fuse on the lamp housing (marked by red arrows on the pictures).
When the 2000hrs period has passed the projector sends a short pulse to this fuse and fries it.
Now your lamp is "dead" though it's still operable.
You can easily tell if it is your case by measuring the resistance of this fuse. In the case shown on the picture it sits near the lamp on the lamp's housing. One can hide it anywhere but it must be mounted
on the part that is replaced along with the lamp.
If it's blown then the recovery is easy. Find a similar fuse and solder it in the blown fuse's place.
I didn't have anything handy at the moment I discovered it so I used a piece of thin wire. It's not a real fuse in a sense that it doesn't protect any circuit. It only protects you from saving your money :)
Step 4: Final Touches
Mount everything back, double check the wiring, and try your refurbished projector.