DiscFerret: First working hardware, firmware and microcode!

Roger Merchberger zmerch-cctalk at 30below.com
Mon Oct 25 21:28:23 CDT 2010


On 10/25/2010 01:54 PM, Philip Pemberton wrote:
> Hi guys,

First and foremost: Congratulations!

>    - Some of the component pads are rather small (notably the inductors
> and Schottky diodes in the power supply). This makes it hard to heat
> both the pad and the component pin at the same time, and thus makes the
> parts a bit of a pig to solder. I worked around this with a hot-air gun,
> preheater and solder paste... later boards will have bigger pads.
>    - The power supply chip is a QFN with pads under the chip. The only
> way to solder it down is to use a hot-air gun... unfortunately TI don't
> make this chip in a more accessible package, and the only viable
> alternative would have nearly doubled the size of the power supply.

[[ assuming I didn't mis-read the statement, and I'm teaching your 
grandmother to suck eggs... ;-) ]]

The only thing I might be able to contribute to this discussion (as I'm 
barely figuring out basic PAL/GAL logic in WinCUPL right now) is:

Instead of a heat gun, have you tried a mini electric oven or what we 
call in the US a "toaster oven?"

http://store.curiousinventor.com/guides/Surface_Mount_Soldering/Solder_Paste_and_Toaster_Oven/

http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=59

http://www.seattlerobotics.org/encoder/200006/oven_art.htm

I pointed a co-worker towards these articles about a year ago when he 
mentioned he had a JetDirect board that quit working and he thought it 
was a "chip with no pins" that could be at fault; he followed the 
directions, repaired the board and it's been working fine to this day, 
he's repaired a few other items (including an XBox360) in this manner as 
well.

I will say that I have not tried it (yet) as I'm just getting further 
into my hobbies after about 5 years; I'm down to one job instead of 3...

Hope this helps!
Roger "Merch" Merchberger



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