Charleston Group Build
fgentges at mindspring.com
Sun Sep 13 19:52:42 CDT 2009
We had ten people, including myself, in the group build of Charleston
receivers. Several weeks ago we built all ten boards.
The power regulator chips were ordered in the wrong package so we
ordered up the correct package and they arrived. Corky and Dodson went
to tacos and picked up their chips at tacos last Saturday, Sept 5th, and
Corky got his installed and got his receiver fired up.
We had another group session last Saturday, Sep 12th. We had six
receivers to bring up at this session.
We had to learn how to solder the regulators to the board with regular
solder and a regular temperature controlled iron. We did find that we
needed to tin the ground tab with the regular solder as it was intially
tined with RoHS (Reduction of Hazardous Substances, lead free) solder.
Then we could put the regulator down with the vacuum pick up tool and
initially soldering down the ground tab. Once secured with that, the
remaining leads were soldered. Removing the solder left from the reflow
process was too touchy and we lifted a pc board land.
We built a little test fixture from an old floppy disk cable harvested
from a dumpster grade computer. By cutting off all the cable leads
except for the last three next to one end we could strip and solder two
of them and cut off the third one in between. The fixture was connected
to a lab power supply that produced 5 volts and had adjustable current
limiting and both indicated on a meter. We were able to limit the
current to about 230 milliamps. By plugging the receiver into the
fixture we could quickly check for proper current draw from the
receivers. We found some correct and some were too low. After some
touching up of the solder connections to the regulators all receivers
came up with about the same current of 210 milliamps. This proved to be
a very useful initial check out prior to connecting to the Nexsys2 board.
Once the proper power current was verified the receivers were connected
to the Nexsys2 board and then checked for full operation. We found one
capacitor that had tipped up (tombstoned)and was not making contact.
Once that was fixed, that receiver came up and worked.
In the end we started with six receivers and ended with six working
receivers. Counting Corky's receiver, we have three more to get up and
working and we feel confident we can do this. Indeed, a good day had by
More information about the Tacos