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View Full Version : Scrap Yard Gloat. Also, depopulating circuit boards?



macona
05-08-2010, 06:25 PM
Here are some goodies I picked up at the scrap yard last week. My friend was able to get in with them and dig through their stuff. First is a Metcal MX500P-11 rework soldering station with wand. Didnt work when I got it home. Modded a screwdriver to get it open and eventually found an unhappy little metal film cap. .33uf at 63v. All I had was a .22uf at 100v. Put it in and it works. These units are great. This model heats the tip inductively with 13.56MHz @ 40w. Temp is set by the tip. The material of the tip is selected by it curie point so no thermostats. The tips heat in less than 20 seconds. New price on the base station is $425 and $95 for the wand. They have dropped in price since this is an old model. I also have the cheaper SP200 model in my garage.

Next is a VFD made by Cerus Industrial. Apparently this is the new name for LG. 3HP, Flux Vector, the works. No dust on the fan blades! Seems to work good. One real neat thing about this drive is it will support driving two different motors (Not at the same time). You can set an input to switch between the two. Activating the input will shut down the first motor, activate a contactor and start the other based on a set of parameters specifically for that motor.

Last is a little Spencer regenerative blower. 40CFM & 40inH2O max. Plan on using this for some torches for working soft glass.

All at 65 cents a pound! Also got a nice Yasawa 750watt servo motor with Harmonic Drive too...

Since I brough up soldering, I have a whole bunch of circuit boards from my welding repair days that I kept because of good parts on them. What is an efficient way to remove the parts? Solder sucker just aint cutting it.

http://farm5.static.flickr.com/4020/4590289536_c86f4bb6bc_b.jpg

http://farm5.static.flickr.com/4020/4590288898_f0936e0ab1_b.jpg

http://farm5.static.flickr.com/4023/4589669139_cff2c76414_b.jpg

Black_Moons
05-08-2010, 06:34 PM
Some people use a torch on the back of the board and hit the board and most of the parts will fall off.. I say most because some use bent leads and will STAY in the board untill pulled out.

I perfer using an attachment I made for a normal vacuum cleaner, that has a 2' long 3/8"~ hose going down to a 10" 1/4" ID aluminum tube (broken arrow body), continious high power suction for removing solder, just hold iron to solder point and bring wand overtop once it melts.
Aluminum Tube sometimes gets cloged with solder, but it doesnt stick worth a damn so any long stiff object can push it through, and its not hot enough to stick much to the 3/8" PVC tube, and not hot enough to stick at all inside the vacuum cleaner.

Warning: with this much restriction I would'nt run the vacuum for more then a few mins at a time, as it will likey overheat as most vacuums use the exhausted to cool the motor.

dp
05-08-2010, 07:11 PM
I swear I thought this was another goat thread. Nice score!

Don Young
05-08-2010, 08:57 PM
I have used a heat gun to melt solder on the back of circuit boards. A sharp rap on the bench top will cleanly remove anything without crimped leads. It takes a little trial and error to get the heat and rapping just right but then it is very fast. I have not tried it on surface mounts but it should work if you can keep from overheating the components.

Bruce Griffing
05-08-2010, 09:16 PM
There are hot desoldering tool plans on the web. If you want to recover gull wing flat ic's, hot air works pretty well. BGA's (ball grid arrays) are difficult. The solder sucker works OK on through hole devices with 2 or 3 leads. For through hole IC's, you need a desoldering tool in the shape of the lead layout.

wierdscience
05-08-2010, 09:27 PM
Good haul!

Whenever I'm out at the local yard I look for indutrial control cabinets and raid them.VFD's,x-formers,push buttons,relays haven't bought much new in years.

Evan
05-08-2010, 10:08 PM
Hot air gun and slap on floor is how I do it. Actually the smaller the part the less it is likely to be fried since the part will cool much faster than a large part. The smaller the part the greater the surface area to volume ratio.

The most difficult to salvage parts are LCD displays that are soldered in. Surprisingly though they can be heated to the point the entire display turns black and they will recover when they cool down.

macona
05-08-2010, 11:12 PM
I do have a leister hot air gun. It works OK but ya got to take a shower afterwards!

Ken_Shea
05-08-2010, 11:16 PM
I do have a leister hot air gun. It works OK but ya got to take a shower afterwards!

Yur not timing it right, just wait till the end of the month to do it :D

macona
05-08-2010, 11:54 PM
Yeah, but that would leave me a whole 'nother month of smelling like burnt circuit boards! ;)

snowman
05-09-2010, 12:44 AM
dang...my scrapyards never get anything this fun. last time i saw a full control panel was...

either that, or they are crushed on the way in :-)