Old TV and CRT monitor innards

[Jeff Root]

I just spent most of the morning taking apart an old NEC Multisync
computer monitor to see if there were any potentially useful bits inside.
I have a tuna can full of screws. :)

Are there any pieces that would be particulary valuable for tinkering?
I want to get rid of anything that isn't worth keeping, but I'm one of
those who has a hard time throwing out anything that might ever be
used again.

I have another monitor and a combination TV/monitor that I could
also tear apart, or I could save my time, fingers, and back and just
take them to the county recycling center. (What they do with them,
I don't know. I also don't know why my back is so sore from this.)

-- Jeff, in Minneapolis

[swampyankee]

Well, the CRT monitors have quite a lot of recyclable stuff in them.

[JustAFriend]

...just watch out for the crt flyback transformer, it carries about 40,000volts even when the monitor isn't plugged into the wall and can REALLY put a hurt on you if you don't know what you're doing....

;-)

[Jeff Root]

These have all been unplugged for over a year. :) Thanks, though!

-- Jeff, in Minneapolis

[BigDon]

Jeff, I'm echoing Justafriend for the readers at home.

I've seen two months not be long enough. I just texted my resident tech on this issue.

[neilzero]

Hi Jeff: Yes a CRT will occasionally snap when shorted after a month of being unplugged. dito for an occasional capacitor. Decades ago I pulled a cheap TV completely submerged from a swamp. I removed most of the components, Let them dry out somewhat in the typical 70% Florida humidity for a few weeks then tested. 90% of the capacitors had leakage of a micro amp or less at their rated voltage. 90% of the resistors were still within the tolerance marked on them. I was impressed. The TV may have been submerged for a year as it had lots of rust on the steel parts. Even the rusted transformers still worked. Neil

[cjameshuff]

...just watch out for the crt flyback transformer, it carries about 40,000volts even when the monitor isn't plugged into the wall and can REALLY put a hurt on you if you don't know what you're doing....

The flyback isn't the hazard, the CRT is. And yes, it can still be dangerous...it's essentially a capacitor with a thick glass dielectric, which makes it very low leakage. There may be a bleeder resistor to discharge it...but there may not be.

There's a few things you can hack them to do...make a crude oscilloscope or XY display.

[Tuckerfan]

It'd be nice if there was a "parts" wiki, where you could enter in the name/model number of a device and get information on which parts were valuable (with links to sample projects), which ones were useless, and which ones were considered hazmat. (The CRT tubes often contain lots of lead, which makes them hazardous waste.) tie-it with a craigslist/eBay/etsy-type set up, with people listing parts they've got that they won't be needing for any of their projects, as well as listings for recyclers/places to take the hazardous stuff, and you could probably turn a nice profit from the site.

(If anyone actually does this, I want a few shares of stock in the company or a modest cash settlement for giving you the idea! ;))

[mugaliens]

It's worth a buck-fifty, but the postage is $6.95!

[TrAI]

Hmmm... I would say that the usefulness of any part from any electronic device depends on your knowledge and what you wish to do. After all, you could potentialy use all the parts for something.

[dgavin]

The electron beam amiling coils ate the base of the CRT tube are very usefully if the insulation hasn't become too heat streesed.

I used to wrap my own transformers or induction coils from them:)

One time made a heck of a dipole anteane out of a set of beam aiming coils and could pull signals in from some very distance FM stations. Also pulled in a lot more interference lol

[Jeff Root]

The electron beam aiming coils ate the base of the CRT tube are very
useful if the insulation hasn't become too heat stressed.
Huh. That's practically the only part of the monitor that I haven't
pulled apart and didn't intend to pull apart.

I took out nearly all the screws and washers, and the wires with
connectors attached. The plastic case will go in the dumpster. The
steel will probably have to go to the county recycling, since I'm not
sure regular recycling pickup takes anything but cans. Three circuit
boards have loads of parts, but they all have very short leads, or no
leads at all. It isn't apparent that I can make any use of them.

I'm relucant to open up the other two-- Doing so just spreads the
stuff around so it takes up even MORE space!

-- Jeff, in Minneapolis

[Tuckerfan]

Hmmm... I would say that the usefulness of any part from any electronic device depends on your knowledge and what you wish to do. After all, you could potentialy use all the parts for something.

Which is where the "sample projects" bit comes in. If one could key in their VCR and discover that it contained almost all the parts necessary to make an automatic cat feeder, they might decide to build one.

[Jeff Root]

I sorta liked the idea at first, but the automatic cat feeder convinces me!
How do we get someone competent to actually build and run the website?

As long as all that crud is sitting all over the floor just waiting to be
stepped on, I'll take this oportunity to put off dealing with it yet again
by typing up a list of initials I found printed on the circuit boards, and
my best guesses as to what they stand for:


C Capacitor
CN Connector
CR ?
CX Crystal ?
D Diode
F Fuse
FL some kind of coil
GND Ground
IC Integrated circuit
J Jumper
L Inductor coil
MC a small integrated network of capacitors?
MR a small integrated network of resistors?
PC ?
Q Transistor
R Resistor
RL Relay
SW Switch
T Transformer
TH ?
TP Test point
VR Variable resistor
X Crystal
ZD Zener diode

Corrections or additions to this list will be appreciated, but what I'd really
appreciate is some advice whether to keep any of this junk or throw it all
away. (If those little "RL" things are indeed relays, I'll certainly at least
save them. I'm a sucker for relays.)

Two of the boards are actually rather nice-looking just as they are,
although I did rip out the biggest IC chip from one because it was pretty
firmly attached to a heat sink that I wanted to remove. So that board
has a slight blemish.

-- Jeff, in Minneapolis

[Ara Pacis]

You can use the flyback transformer to make a plasma sphere, I've got a book somewhere that explains how. Look for DIY and Maker sites on the internet for help. The sites kipkay.com, makezine.com and instructables.com may help.

[Jeff Root]

Is the flyback transformer the thing that is covered with black dust?
Some parts are very clean; others are filthy. The filthy parts appear
to be close to the high voltage, but I'm not sure in every case exactly
what is high voltage and what isn't.

I've put all the remains of the first monitor out of sight. The three boards
are in "temporary" storage for possible future part extraction. The CRT is
hidden underneath the stairs at the back of the building until I can take it
to the county recycling center. Please don't tell the building manager.

Two more to go, but not today.

Does the word "Maker" have some special significance? You capitalized it
like a proper noun.

-- Jeff, in Minneapolis

[TrAI]

Is the flyback transformer the thing that is covered with black dust?
Some parts are very clean; others are filthy. The filthy parts appear
to be close to the high voltage, but I'm not sure in every case exactly
what is high voltage and what isn't.

...

The flyback transformer in a CRT monitor will be a rather large component connected to the CRT by a wire with a rather thick insulation and an insulating cup covering the connector, it will probably be easy to find.

When operating the high tension(HT) area will have a high positive tension, and be surrounded by a static electric field. The dirt was likely particles/dust in the air that was attracted to this field, and was deposited on or near to the high tension parts, it is pretty common for older CRT displays to be rather caked with the stuff.

The actual HT parts are pretty much the CR-tube, the HT wire and the flyback, but I suppose it really depends on what potential you are measuring relative to...

[neilzero]

For short lead components, I wrap two or three strands of fine tinned wire around a stump as short as 3 millimeters and solder. That yields 4 or 6 leads instead of one. Often a sizable advantage. Neil

[iquestor]

I probably built that monitor, or rather, saw it built. I used to be a process engineer at NEC in McDonough, GA. We made the MultiSync series 15, 16 and 17 ". I'b be interested to hear what model it is and shen it was built!

[tashirosgt]

I still use a model JC-1734VMA manufactured AUG 1995. Remanufactured MAY 1996

[Jeff Root]

Multisync 5FGe. I must have that written down somewhere, but I don't
recall where so I went back to the stairwell and turned the CRT on its side.
I left the front of the case on the tube to make it easier to handle.

Two things I noticed while looking at all those parts: Very few were
marked 'NEC', and I don't think I saw any Japanese anywhere. All English.
What's with that? Most or all of the parts must have been made in Japan.
Why weren't at least some of them labled in Japanese?

The majority of the black dust appears to be on the transformer and the
area of the board around it. I've noticed that some CRTs gather dust on
their faces while operating, and others don't. If I recall correctly, the NEC
monitor did NOT get dusty. I rarely had to clean it, compared to some
other monitors. The Dell CRT monitor I've been using for the last year or
two-- which was just supposed to be a stopgap until I got a replacement,
which I now have, not set up yet-- is intermediate, picking up some dust,
but not much. The ones that pick up the most dust feel staticky when I
touch them, and give a rather unpleasent sensation when I put my face
close to the tube.

-- Jeff, in Minneapolis

[Ara Pacis]

Does the word "Maker" have some special significance? You capitalized it like a proper noun.

http://en.wikipedia.org/wiki/Make_(magazine)#Makers
Mr Jalopy and the Maker Movement at NPR (http://www.npr.org/templates/story/story.php?storyId=92508461)

The Maker's Bill of Rights (http://makezine.com/04/ownyourown/) at Make Magazine

[slang]

list of initials I found printed on the circuit boards, and my best guesses as to what they stand for:


TH ?

Thyristor?

[TrAI]

Multisync 5FGe. I must have that written down somewhere, but I don't
recall where so I went back to the stairwell and turned the CRT on its side.
I left the front of the case on the tube to make it easier to handle.

Two things I noticed while looking at all those parts: Very few were
marked 'NEC', and I don't think I saw any Japanese anywhere. All English.
What's with that? Most or all of the parts must have been made in Japan.
Why weren't at least some of them labled in Japanese?

It is pretty common for electronics manufacturers to by components from other manufacturers for their devices, it is in many cases cheaper to use well known and tried components from other manufacturers than use resources on developing ones own to do the same thing, many manufacturers specialize in certain types of components too, and will have less experience with others. Also, the component fab and the factory making the devices tend to be seperate subcompanies, and generaly isn't very closely connected, so I would think the factories often would buy the components that are cheap and do the job well, even if it is from some other company.

I really do not see why you would expect the components to be marked in japanese, if they were, a large number of potential costumers wouldn't be able to read the markings. It really would be rather unpractical for all electronics people to have to learn all the writing systems of the world, you know...



The majority of the black dust appears to be on the transformer and the
area of the board around it. I've noticed that some CRTs gather dust on
their faces while operating, and others don't. If I recall correctly, the NEC
monitor did NOT get dusty. I rarely had to clean it, compared to some
other monitors. The Dell CRT monitor I've been using for the last year or
two-- which was just supposed to be a stopgap until I got a replacement,
which I now have, not set up yet-- is intermediate, picking up some dust,
but not much. The ones that pick up the most dust feel staticky when I
touch them, and give a rather unpleasent sensation when I put my face
close to the tube.

-- Jeff, in Minneapolis

Newer CRTs, especially those used in computer monitors have built in features to dissipate static electricity(for example, the screen may be coated with a conductive coating), Though these were probably implimented to reduce the discomforts of sitting close to a highly charged object and to prevent ESD from destroying sensitive electronics placed close to the monitor, it also reduces the amount of dust attracted to the screen.

[Ara Pacis]

It is pretty common for electronics manufacturers to by components from other manufacturers for their devices, it is in many cases cheaper to use well known and tried components from other manufacturers than use resources on developing ones own to do the same thing, many manufacturers specialize in certain types of components too, and will have less experience with others. Also, the component fab and the factory making the devices tend to be seperate subcompanies, and generaly isn't very closely connected, so I would think the factories often would buy the components that are cheap and do the job well, even if it is from some other company.

Not to mention patent and licensing issues.