Any parts worth keeping from PC monitor?

[UncleJessie]

I'm about to throw away an old 15" CTX PC monitor but may salvage it for parts first. I've seen a couple of xformers that I'll probably remove. Are there any parts in particular that I should look for which may be applicable to future diy audio projects?

Thx.
UncleJessie

[EC8010]

The ferrite core from the line output transformer can be used as the basis of an RF choke. The line output transistor will be a high-voltage device that can be used in an HT regulator. If you're feeling really grungy, the field scan IC is effectively a 3W (or so) audio amplifier. There might be other bits, but I can't think of them at the moment.

[planet10]

Monitors often will have good heat-sinks in them and decent high voltage 200-450V caps. The deflection coils are sometimes made with litz-like wire which can be used for making inductors.

I get a lot of dead monitors -- i try to recycle as much of them as possible (ie plastic goes towards making plastic lumber) -- i hate to see them hit the landfills.

dave

[DIY_Peter]

I also have access to many old CRT's that are going to thrown away.

There are many electrolytic caps in them. some high values to.

Are these caps good for audio circuits?

I also found a lot of caps that are red or blue and have the shape of a cylinder that has been squeezed. There's probably a good english word for this shape, but that's the best way I can describe it
They look like they're made of epoxy. What kind are they? and are they any good?

Another type I found were rectangular shape caps that had AC voltage ratings (250V). Can I use those?

I'm planning on building the P3a, using only recycled parts.

I also heared that electrolytic caps get worse over the years. How fast do they get worse?

[Sch3mat1c]

Polyester, or using the brand name, mylar, caps. Good stuff.

I once pulled a 3.5uF (i.e. marked "355") 200V cap from a monitor. It's in a speaker now.

The HV transistors (HOT (Horizontal Output Transistor) might be on a heatsink near the FBT, and you might have one (or a MOSFET) for the switching supply) are good stuff, usually rated for a good couple of amps and a kV or so.
The 'lytics in the PSU are usually good on size and voltage.

Tim

[planet10]

Originally posted by DIY_Peter
Are these caps good for audio circuits?

These caps usually have to work well at high frequencies, so are probably among the best asily found recycled caps.

I also found a lot of caps that are red or blue and have the shape of a cylinder that has been squeezed. There's probably a good english word for this shape, but that's the best way I can describe it

Are you sure those aren'y encapsulated inductors. You could also be describing a mylar cap. Same uses as the square ones below.

Another type I found were rectangular shape caps that had AC voltage ratings (250V). Can I use those?

Non-polar caps. These are plastic of various sorts. Can be used for cross-overs or coupling caps.

I also heared that electrolytic caps get worse over the years. How fast do they get worse?

Yes they do, but the usual life-span of a monitor is significantly less.

dave

[DIY_Peter]

Originally posted by planet10


Are you sure those aren't encapsulated inductors. You could also be describing a mylar cap. Same uses as the square ones below.

yes I'm sure they are caps. I can see it on the markings on the board.

I've seen some other pics on websites, and they look like mylar caps.

Some have the inscription MEF on them. Metal film?

The rectangular shaped ones with the high AC voltage ratings have MKT written on them.

Difficult to identify all these caps, ofr a beginner like me though. But I'm learning.

Are electrolitic caps good enough for SS amps? or are they to unstable?

[planet10]

Originally posted by DIY_Peter
MKT written on them.

That brand name has a good rep... there are a couple a threads referncing them.

Are electrolitic caps good enough for SS amps? or are they to unstable?

Typically for larger values elcos are used, just because using all plastic gets really expensive both dollar-wise & real-estate wise. The rule-of-thumb i'd use would be if you can find & fit one of the plastic caps use it otherwise an elso (but watch the polarity)

dave

[EC8010]

Originally posted by planet10
Yes they do, but the usual life-span of a monitor is significantly less.

Er, it's usually those electrolytic capacitors that determine the lifetime of the monitor. (Especially if some pillock hasn't understood the concept of ripple current and its relation to heating in ESR and capacitor lifetime.) I want it to be clearly understood that I am not referring to Vistek monitors.

Properly-designed monitors contain good-quality capacitors around the line-scan and PSU department.

[planet10]

Originally posted by EC8010
Er, it's usually those electrolytic capacitors that determine the lifetime of the monitor

It is a good idea to check any caps you pull... but many of the monitors i pull apart are actually working, but have screen burn so bad they are useless. Also of note is that since the store i get most of the deads thru is in the habit of only selling premium monitors (i wouldn't work there [part-time now] otherwise) so the quality of the guts i get are above run-of-the mill.

dave