What is harvest-worthy from an old CRT monitor?

[daveindelaware]

I have a few dead CRT monitors that I'd like to take apart. Mainly, just to see what's inside them (I've never seen the guts of one before). But also, to hopefully harvest whatever is usable from them.

So, what should I keep, and what's junk?

What do you guys/girls get out of CRT monitors?

Don't CRT's generate X-Rays or something? Is that good or bad for a DIY tinkerer?

Thanks for your opinions, suggestions, and insight!

 

[Flaminpyro]

Rember to short out the second anode on the CRT or you could get a real nasty shock that will make you

 

[photonaholic]

The cord comes to mind as useful.....:crackup:

Really, I have dismantled a few, unless you need some copper wire or a flyback transformer, they are junk.

 

[daveindelaware]

I'm looking at the board to the first one I opened. There are tons of little resistors and a few voltage regulators (which have heat sinks, too!). The heat sinks may be worth the harvest alone. And just to give me something to tinker with.

BUT, upon closer inspection, it appears that the underside of the board has burn marks around some of the soldered components, namely the transformer (T702) and a big capacitor (C905). I'm guessing this monitor was fried by a surge which caused this scorched discolored solder around some of the pins to these components? Is that a logical guess at to why this was offered as "free - don't know if it works"?

If the unit got fried, are all the components fried, too?

 

[charliebruce]

Passives like resistors will most likely be fine, and unless the transformers have visual signs of damage (damaged copper) and are not conducting I'd say they'd probably work too. I wouldn't trust the capacitors - look at the tops to see if they are domed, then measure them on a multimeter, but they're not worth putting in anything you'd rely on. It's probably not worth salvaging much else unless you have any use for the chips, power/video connectors, a bit of copper and coils, and heatsinks as you said.

 

[kiyoukan]

As far as monitors go. might be a bit off topic but...
I got word that after a large lightening storm my old high school lost over 9 19in lcd monitors. and 2 crts and 3 psus.
I picked all of them up for free and wouldn't you know it.
I fixed almost every one by replacing the caps.
if you want to fix it replace the caps there cheap and are normally the first thing to go.
Be careful of the large 300V caps discharge them first or pay a nasty price. ("where did my arm hair go?")
this is a good way to make money i sold them back their fixed monitors for 60$ a piece.
it would have been 110-130 for new ones so i helped them out, was kinda looking forward to a circle desk with lcds all around it.

 

[HaloBlu]

Nice kiyoukan. You made over $800 total right?

 

[RA_pierce]

I like to take the little momentary switches. They come in handy for lasers.
When I was building a lot of pen lasers for friends and all I needed a few.
An old CRT monitor is where I found some.

Heatsinks and extra wire are also always nice finds. Other than that, the rest is junk.

 

[kiyoukan]

i made about 540 but the caps for everything cost me about 40$ or a little bit more, but yes doing repair work is profitable. just wish i didn't wait for a lighting storm to make money.
although virus and pc maintenance is where the money is at.
Speaking of crts what happens if you break the vacuum tube? i have always wanted to do it but always been told to NEVER do it...

 

[RA_pierce]

Cathode-Ray Tubes

I just googled CRTs and got some info on safety.

 

[Ears and Eggs]

Well this sucks. My family's 25" CRT TV just croaked today. :cryyy: No idea what happened, it just turned off by itself in the middle of a show and now it won't turn on again. There was a severe lighting storm in the area a couple hours ago though. Now I am wondering if I should risk opening it to try and harvest parts or just throw it out. I am a little nervous about CRT TVs after we had one catch fire and fill the house with this horrible smoke a couple years back. Fortunately it did not spread to anything else.

 

[kiyoukan]

well if its worth the money and the time to fix just open it up and look at the psu as others said before the caps will have a rounded top and not flat try replacing them. a cheap fix.
The tubes take a good beating to break them i have dropped mine from 2ft down a set of stairs and it was perfectly fine.
So to see whats in the tube i need a hermetically sealed suit and a rifle, good to know.
Whos got the suit?

 

[phoenix77]

@ 2007 Revolution, maybe you can open it up & look for the troubles that "kiyoukan" talked about that he encountered the CRT Monitors he repaired. You just might be able to fix it yourself by swapping out a capacitor,(watch the hair on your arms though, lol")!

If you don't mind me adding my own $00.02 here, in my limited experience working with electronic equipment, I've noticed that frequently, where the power cord enters the units casing, attached to the chassis or framework, is a simple in-line power fuse. Our microwave & my son's 19" color TV were both donated to me as "broken". Both of them were fixed inside of a 1/2 hour each with some quick work with a screwdriver, a DMM, (to check the power fuses), & a couple bucks for replacement fuses. That was 5 years ago, & both units STILL work fine. GOOD LUCK with your project, whichever way you decide to go. rob

 

[BShanahan14rulz]

Discharge all the big caps. Remember, the big glass tube itself is used as a HV cap as well, discharge that too. The inner surface and outer surface are metalized, and the glass is the dielectric. The big fat wire that looks like it is suction cupped is what I believe connects to the inner electrode of this "capacitor." I remember the first CRT I harvested from... woke up about 20 minutes later on my back. Also, there are many wires going from here to there, and lots of exposed metal. Be careful what you touch.

Check your regulators. I've found a few decent sharp 5V regs in stuff that I have hacked apart. Heatsinks are useful too, as they will probably fit your LM317 chips too

Transformer can be useful too, depending on the size.

Flybacks can be fun, I just don't know anything about them.


As far as what's in the tube...
There's this neat assembly in the back, the electron guns. They look like little coiled filaments. I bet they are some kind of special metal! I just kept the thing because it looked cool, made a nice christmas tree ornament.
The screen is glass coated in phosphors, very messy, hard to get off your fingers. In front of the screen is a thin steel foil. It is positioned just behind the phosphored surface, and is perforated. Easily damaged, not much interesting really. Maybe do somethign strange if you shine a laser through it, iono.

Basically, I'd recommend against busting apart the tube, but harvest what you want from the electronics, after taking the correct precautions. Look up part numbers on the internet, you never know when you might find something really nice.

Also, would be nice if you had someone who could check up on you from time to time, make sure you haven't been electrocuted. Have fun!

 

[daveindelaware]

Thanks everyone for your input! I think I'll just go after the regulators and heatsinks, wire, and a few resistors off of the board and trash the rest of it. The entire CRT safety thing scares me, so I'll be avoiding that area.


These are probably dumb questions, but just how long do the capacitors hold a charge, and how do you discharge them? I ask only because these monitors had been sitting in someone's garage and not used for quite a long time.

 

[kiyoukan]

get a screw driver with plastic handles and then just short the caps out. they can hold charges for a very long time i have heard of things holding a charge for over 14 months. but it has a lot of factors just better to be safe than sorry.