u11 problems

General discussion and support for the Peaberry SDR V1.

u11 problems

Postby w8kfj » Sat Dec 29, 2012 5:33 pm

I wish now I had ordered U10 and U11 installed. I hoped to learn something from this adventure, and I have learned something - these pins are REALLY close! After removing a few solder bridges, things are looking up. However, I can't seem to remove a short between pins 27 and 28. If I have damaged something, could things still work, since those pins are used for programming - as long as I don't need to reprogram? Will things fry if I fire it up for the next test? If I need to send it back, should I finish construction - without any more tests?

I just wanted to add - the instructions are excellent, maybe even Heathkit class!. The schematics help, but a little discussion of signal paths, with what happens inside those mysterious chips (U11) would be useful. Thanks for your interesting design, and for your help, David.
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Re: u11 problems

Postby AE9RB » Sat Dec 29, 2012 5:55 pm

There's a block diagram that shows the signal paths and what U11 does:

I can't always predict what will happen if you try to power up with shorted pins. I strongly recommend you not do that. Things are known to burn up when there are shorts.

Use desoldering wick to remove shorts on the ICs. If this is troublesome, buy a different brand. All wick is not created equal.
73 David AE9RB
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