Salvaging components from scrap boards.

[dr peppers]

I have loads of scrap boards, and recently I tried an idea for salvaging components after seeing a hot air smd rework station in operation.

I got my cheapo diy hot air paint stripper and wafted it around the back of a scrap tv board while it was in the vice, and tugged at some of the comps round the front with long nose pliers expecting not a lot to happen.

It did, the whole board with the exception of resistors was stripped and in the parts tray in about 10 mins.

I'm sure this method will have been practiced by loads of folks, but its certainly worth a go if you have not allready, most of my little chokes and switch mode ferrites come from salvage stock and it save a lot of time and fiddling.

 

[Sceadwian]

I proscribe this method of salvaging scrap boards as well. I've current stopped taking in dead boards due to the fact that I have more parts to deal with right now than I can probably use in the next year.

 

[cowboybob]

Incredible idea dr peppers. Outstanding.

This is one of those "DUH" moments for me.

Thank you, sir.

Two posts into the forum and you hit a homer, at least with me.

CBB

 

[ronsimpson]

I use a toaster oven to heat the entire board. Then I turn the board upside down and drop it on the counter. All the parts fall off.
OR I reach in the oven and pluck off some off some of the parts.

 

[dr peppers]

Any way of doing this involves burned fingers.

Glad to have done a homer.

I'm not a TV expert, whats the principle behind the inductor with the magnet inside it usually found in the deflection circuit, I think its a saturable core inductor, is the idea to make retrace resonance with the deflection windings?

 

[jpanhalt]

Or use a propane torch. It has been reported many times. Some people let the parts drop into water, but that probably is not necessary.

@Sceadwian: Why do you proscribe it?

John

 

[ronsimpson]

A
I'm not a TV expert, whats the principle behind the inductor with the magnet inside it usually found in the deflection circuit, I think its a saturable core inductor, is the idea to make retrace resonance with the deflection windings?

Linearity coil. It us used to make the left side/right side the same size in a TV or CRT monitor. You are right the coil saturates more in one direction.

 

[dr peppers]

Right then so the inductance is the same both directions, but the satuartion limit is not due to its built in magnet, so one way its acts as an inductance and the other way it acts as an inductance up to a certain point, then saturates and becomes a short, thus linearising the horizontal trace.
Got that now.

 

[Sceadwian]

jpan.. I've tried a torch, an electric heat gun is much better, again I have boxes of components from this.

Not for those weak in categorical declarations, the sheer number of components you get make it not for the weak. It's very simple and will net you literally buckets of components.

 

[ronsimpson]

Right then so the inductance is the same both directions, but the satuartion limit is not due to its built in magnet, so one way its acts as an inductance and the other way it acts as an inductance up to a certain point, then saturates and becomes a short, thus linearising the horizontal trace.
Got that now.

The magnet causes the coil to saturate in one direction and not in the other.
When saturated its inductance is very low.
When not saturated its inductance is hi. (10 to 20uH depending on the inductance of the horizontal deflection yoke)

 

[dr peppers]

I just made up a rig, the inductor is connected to my bench supply via a 100r resistor, and my lc bridge is measuring the inductor, the lc bridge input is ac coupled so the dc doesnt affect it much.
I get 40uH whats written on this particular inductor, I can change the inductance easily, one polarity affects much more than the other, the inductance wont go less than 10uH, might not be enough current through it.
But it certainly shows that the coil has polarity properties.

This is one of those things I've wanted to know for a while.