Hitachi Rear Projection TV - No Pics Yet, soon

[Trendkilla254]

So after seeing a few threads on using lenses from old big screen TV's, I happen to see one on the side of the road when I stopped by my parent's house tonight. I loaded that sucker right up. Game on...

(More to come once I have time to tear into it)

I found this video. See my post below for more details. After doing this I saw this video and it appears to be the exact same model.

https://www.youtube.com/watch?v=AF53gOItsKs

 

[VisibleGreen]

Re: Hitachi Rear Projection TV

Please do. I got a few old projection tvs and I'd love to know what I could do with them.

 

[Gabe]

Re: Hitachi Rear Projection TV

Oh, the optics you'll find...
Anybody know how fresnel lenses fair up against laser beams? Same as classic lenses?

 

[RedCowboy]

Re: Hitachi Rear Projection TV

I have 3 big projection TV's in my garage right now that I recently picked up from the curb, the lady homeowner said please do take them away, 1 even plays.

The earlier models have 3 cathode ray tubes with lenses on top, the closest lens has a cavity between it filled with glycerin type fluid to keep it from burning up but the top lenses are nice big ones, the one in my hand right now is just over 3 inches wide and it's almost plano convex but the back side is the slightest bit convex as well, it is very strong and high quality glass.

Now the later model big screen projection TV's have the DLP chip and a super bright mercury vapor bulb like the non hybrid projectors and they have a nice optics train, lots of lenses and filters and they all have a big front surface mirror at the back and the Fresnel sheet lenses at the screen.

I hope someday we have laser TV's in the junk pile.

WARNING, I said glycerin type fluid that is in most cases monoyethelene glycol and it is toxic if you ingest it, treat it just like automotive antifreeze. Wash your hands and do not allow pets to lick it off their paws so clean up any spills.
You are responsible for your actions so use caution.

 

[Trendkilla254]

Re: Hitachi Rear Projection TV

So I went crazy with my Cordless Drill and took all the screws off the back. I was thinking I would need to go from the bottom. I was wrong. I just removed the top half of the backside. I was able to easily detach the 3 lens "modules". I don't know what they are actually called. There are 3 large black plastic housings with lenses on the inside. I took one of the 3 apart. It contained 4 lenses. I will include pictures at a later time. (I have to use my wife's phone, mine is broken).

3 lenses are plastic of some sort. All shaped a bit differently. I'll get more info on them with pictures soon.
1 lens is glass. This lens is curves outward on both sides.

What I don't know is how the "Module" with all the lenses installed would work. It does have the ability to "zoom". Meaning the inner housing moves forward and back. (The lenses stay the same distance from each other. It just moved the entire setup further or closer to the source.

I took one "Module" completely apart and will at some point get some glycerin and fog up the garage and have a go at them with my 515nm 5mw. Hopefully it will be bright enough to see some changes.

I would be willing to mail 1 unit out to someone for free + shipping IF you already know what needs to be done to make this a successful beam expander. I was thinking of using PVC like http://laserpointerforums.com/f44/445nm-laser-diy-beam-expander-2-beam-95090.html. I don't know enough yet to finish this project. I also don't want to sound like the "How do I" posts. I will be searching and I will be trying to get all the information I need. If you would like to contribute information feel free. Please refrain from telling me to search. If you have a spoon I will eat from it, however I will eat with my hands... no spoon is required.

I will when time permits post all the model numbers & pictures. I will also post links I find useful as well. Again I saw the TV and knew there was some optics in it that may or may not be useful. I don't currently have the know how to do anything with them, but I felt I might as well grab them since it is free.

IF it works like I hope I will leave all 4 lenses in the plastic housing it comes in and just add on some adapters. This should allow me to focus with the adjustment. I could be way off base though.

More to come, stay tuned.

Oh, the optics you'll find...
Anybody know how fresnel lenses fair up against laser beams? Same as classic lenses?

I didn't keep the fresnel lens. I made the mistake of trying to get the color filters out of it as well. (I don't know why I did this, I just thought "why not")
Apparently there is a Liquid in DLP rear projections... Imagine that. I assume it's mineral oil. It had the viscosity and appearance of mineral oil. It didn't appear to be water, too thick. I'm 99% sure it is supposed to be there, It was sealed behind this color filter. There is even a rubber "bulb" That appears to be there to collect air bubbles. I should have added all this up and a light buld should have went off in my head... I think I was just in too much of a "Lets Unscrew This" mode. It was quite messy and I really didn't feel like cleaning it up as it got all over the fresnel lens.


Other than the colored filters (which was not at all necessary) this was VERY VERY easy to disassemble. Just go at it from the TOP not the bottom. From the back side, the top half of the unit.

@RedCowboy: Just re-read your post... So it could be Glycerin, or it could be a combo or Propeline Glycol and Glycerin 70/30. Or Worse it could be Ethelyn Glycol, which is Toxic. Per http://www.electro-tech-online.com/threads/need-to-id-oil-in-rear-projection-tv-lens-3-i-repurposed.126801/ I think I am going leave it alone.

 

[Gabe]

To a make a beam expander with that is as simple as not using a regular lens to start out with, so it's just raw output. Then you take a large lens with a close focal point and adjust until it's focused to infinity. Don't hold this against me though, test it out first before you buy the parts, I may be totally wrong.

 

[RedCowboy]

Re: Hitachi Rear Projection TV

[QUOTE ]@RedCowboy: Just re-read your post... So it could be Glycerin, or it could be a combo or Propeline Glycol and Glycerin 70/30. Or Worse it could be Ethelyn Glycol, which is Toxic. Per Need to ID "oil" in rear projection tv lens' (3) I repurposed | Electronics Forum (Circuits, Projects and Microcontrollers) I think I am going leave it alone.[/QUOTE]

I could have been a little more clear but I had forgotten exactly what it was, I would hope people would not drink some unknown substance found inside household electronics but you are right, it is better to be safe and spell it out. I did make an effort to warn you the old models had coolant inside.

The lens packages I use are from DLP projection TV's and they use a lamp not crt's.

It is almost always monoethylene glycol in the old CRT type projection tv, the DLP type don't use that.

But dissemble at your own risk, I looked it up before I tore one apart years ago and everything I read said just don't drink it and you will be ok.

Ethelyn Glycol was common in automotive antifreeze for a long time and I think still is but newer stuff is made with monoethylene I think.

I have been up to my elbows in automotive antifreeze and I just wash it off, DO NOT DRINK IT, but if you get a bit on your hands, don't panic, just wash it off.

WARNING never spill EG or automotive antifreeze where pets can ingest it, or get it on their paws and lick it off.

Here's the toxicity of EG even though it is not supposed to be used in TV's, it's supposed to be Monoethylene glycol and people buy it in bottles and change it out if the picture gets fuzzy.

Ethylene glycol has been shown to be toxic to humans[12] and is also toxic to domestic pets such as cats and dogs. A toxic dose requiring medical treatment varies but is considered more than 0.1 mL per kg body weight (mL/kg) of pure substance. That is roughly 16 mL of 50% ethylene glycol for an 80 kg adult and 4 mL for a 20 kg child. Poison control centers often use more than a lick or taste in a child or more than a mouthful in an adult as a dose requiring hospital assessment.[13]

The orally lethal dose in humans has been reported as approximately 1.4 mL/kg of pure ethylene glycol.[6] That is approximately 224 mL (7.6 oz.) of 50% ethylene glycol for an 80 kg adult and 56 mL (2 oz.) for a 20 kg child. Although survival with medical treatment has occurred with doses much higher than this, death has occurred with 30 mL of the concentrate in an adult.[14][15][16] In the EU classification of dangerous substances it is 'harmful' (Xn) while more toxic substances are classified as 'toxic' (T) or 'very toxic' (T+). The U.S. Environmental Protection Agency generally puts substances which are lethal at more than 30 g to adults in Toxicity Class III.

Ethylene glycol has a low vapor pressure; it does not evaporate readily at normal temperatures and therefore high concentrations in air or intoxication are unlikely to occur following inhalational exposures.[17] There may be a slight risk of poisoning where mists or fogs are generated, although this rarely leads to poisoning as ethylene glycol causes irritation and coughing when breathed in, alerting victims to its presence.[18] Ethylene glycol is not well absorbed through skin meaning poisoning following dermal exposure is also uncommon.


The instructions for changing out Monoethylene glycol in a projection tv say not to drain it into anything that you are going to eat or drink out of, it's not like getting it on your hands is going to poison you.

 

[Trendkilla254]

Good info, much appreciated. I wasn't sure what it was, nor did I look it up. It was my fault for not paying attention, you did try to tell me.

 

[RedCowboy]

Good info, much appreciated. I wasn't sure what it was, nor did I look it up. It was my fault for not paying attention, you did try to tell me.

There is no need to take that messy part at the base apart anyway, it's just a colored acrylic lens that's useless, the one big glass lens is in the top part and there is a big front surface mirror in the back and the big front fresnel.

The DLP TV's have a bunch of nice optics, those old CRT types just have the 3 heads with a glass lenses a couple acrylics the mirror and front fresnel inside, you crack em open with a screwdriver.

Now you can use the high voltage transformers out of the bottom and make some big sparks, Jacobs ladder, ect.

Thinking about salvaging tv flybacks and I had to make a quick vid with a little high voltage, pretty isn't it?
I bet there's some people here with some tesla coils.