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Soldering Small Components for a Video DA

Video DA Board

Video distribution amplifiers are used to amplify a video signal and split it into multiple outputs so multiple displays can be driven. They are also used to correct the gain of an incoming video signal. [Andrew] was having trouble with the video signal from an interferometer, and found the issue was caused by a low output gain. His solution was to build his own video distribution amplifier.

The THS7374 appeared to be the perfect chip for this application. It’s a four channel video amplifier IC, and only requires a few passive components to run. The only problem was the package: a 14 pin TSSOP with 0.65 mm pitch. Not fun to solder by hand, especially if you don’t have a PCB.

[Andrew]‘s solution was to build his own breakout out of copper-clad board. He worked under a microscope and cut out a pattern for the part, then soldered 30 AWG wire to the pins to make connections. After cleaning off any copper that could cause a short, the board was working, and the video waveform looked great on an oscilloscope.

After testing, even more gain was needed. [Andrew] ended up cascading two of the amplifiers. This method of prototyping doesn’t look easy, but could be worth it when you need a single board.

Comments

  1. Jeff Nichols says:

    HaD, you do more than anyone else to keep people afraid of SMD soldering. I know it looks hard at first, but it’s surprisingly easy once you actually try it.

    • Totally agree. When I first tried SMD soldering, I was terrified of an SOIC8 or a 1206 package. Now they look massive! MSOPs and TSSOPs are a bit of trouble, but with a fine hand, 0.3mm solder, and a pointy soldering iron tip, they’re no bother. Actually, I find my cheap no-brand iron great for this, because it has a big brass rod as the heated member, so I can just file the tip to shape. Tends to dissolve a bit, but there’s plenty of it.

      Once you start working with SMDs, you soon get addicted to seeing how small you can make a board and still be able to solder it!

    • Matt says:

      I think it is faster and easier for passives, as long as you aren’t playing with 0603 packages…but even those aren’t bad under magnification with the proper iron tip and solder. IC’s are more intimidating, but once you learn the tricks and do a few, they are stupid simple as well.

      • Jeff Nichols says:

        I solder 0201s without magnification. Granted, they take a bit longer to do properly than 0402s, but mostly the fear is unwarranted.

        The only thing I found that I couldn’t solder is a BGA (can’t get the tip underneath), and my hot air station worked reasonably well with those. Everything else is no problem.

    • SMD isn’t bad, but prototyping with SMD components can be tedious.

      Also, I thought that video DA chip was cool.

  2. fartface says:

    Really? SMD soldering is super easy. No you cant be a street person with a giant club Radio shack iron. but if you spend a little bit of money on the right tools ANYONE can do SMD work.

    In fact I find SMD work EASIER than through hole and DIP.

    • smilr says:

      If you are cautious, even a dumb club of a 30w of a Radio shack iron can be used for SMD.

      I’ve had good success soldering SO-8, .65 TSSOP and 0603 packages. I’d hate to go much smaller than those, but it can be done.

  3. ColdTurkey says:

    Great work on the DA!
    Also a question to all u fellas who seem to find smd easy:

    Would any of you mind submitting a (very) quick guide or some pointers (or even links)to HAD about the technique/s and methods that work for you? Of course small guage solder and a fine tip but is there anything not-so-obvious we should be using/trying/is generally handy?

    I have looked around for advice to make this easier but a lot of it is conflicting or makes use of a certain method not clearly explained. I’m sure a lot of us here would appreciate and benefit from something like that

  4. echodelta says:

    A Ungar Princess iron is a great to have, not temp-co but deft in the hand. I have done 100 pin replacements. Heat and lift one pin at a time to remove. Even reused one I took off, it wasn’t bad. Hardest is centering the replacement in place.

  5. cantido says:

    >The only problem was the package: a 14 pin TSSOP with 0.65 mm pitch.
    >Not fun to solder by hand, especially if you don’t have a PCB.

    You can get prototyping adapters for those sort of packages off of ebay very cheaply (or if you want you can buy more expensive ones from Digikey, Farnell etc..) and they are a piece of piss to solder. Big tip, lots of flux and some wick just in case… now if you were talking about something like a 184 or 208 pin QFP you might have a point.

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