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Bang good transtor tester DIY M12864 build

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seadog:
Hi Pekka, I've done some SMD replacement. The method that works for me is to use a liquid flux and very small gauge silver loaded solder. I flux the pads and then position the component, the surface tension helps to keep it in place. I then cut tiny pieces of the solder and place a piece by each leg (if it's an I.C.). Then, using a 12 watt iron with needle bit and a head visor, work my way work my way around the component. It's easy if you're patient. My first efforts weren't that good!

awemawson:
Hot air gun works with the right nozzle

PK:
We do a LOT of SMD rework and assembly.

To give you a feel for it, you know that roll of solder you have in your toolbox, or on your bench? Its probably a 250 or maybe a 500g roll and you've had it for years...
When we are making batches of product, we use about 1Kg of solder a day!

The tricks to do good SMD rework (or even hand assembly) are:

Preheat the board. Take it up to 50-80 deg c and (if you can) hold it there. It dramatically reduces the time you spend holding an iron or hot air gun on the job, locally heating a spot to 300+degrees. You'll find the PCB's last many more rework cycles and you can do things like remove small parts with a single tipped iron. Preheating can be as simple as holding the hot air gun on the back of the board until it gets too hot to touch before switching to the other side.

Use flux. Get a no clean flux pen and use it, not solder when putting a part back on. There was enough solder there before, so there's enough solder there now. The flux will let it wet onto the part.

PekkaNF:
Nice info PK, thanks.

Does anybody read OP nowadays? Or does the formus shows only new posts on touchpads or what?

Pekka

dvbydt:
So, yes I had to have the scope - no problems. I bought the one with pre soldered chips. Then the Component Tester but this time I bought the assembled board, like John S.

BUT :-

"I am a Bear of Very Little Brain, and long words Bother Me," Quoting  A. A. Milne.

How do I use it, everyone else seems to know. All the experts show components plugged into the ZIF socket - how do they find out where?
Eventually, like Poo Bear the light dawned. This board has the Mega328 computer chip (Same as Arduino) and has RAM, ROM etc built in. The software configures it as a three terminal tester. Components can be connected to any two of them - resistors, capacitors, diode and inductors. Transistors and other three terminal devices can be tested - magic!

The attachments show the ZIF socket. The figures are not a serial number :doh: but refer to the holes in the ZIF. Two parallel rows, any combination of the holes can be used 1&2, 1&3, or 2&3 or 123 for transistors. There are three pads on the board and three flying leads.

Very happy bear.

I hope that this might help other bears out there.

Ian

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