Re: gEDA-user: buzzing board

["evan foss" <evanfoss@xxxxxxxxx>]

> > How good is the temp. control on your oven?
>
> Er, zero control.  I use a hotplate, which heats only the back of the
> board, so the solder melts before the chips get too hot.  However,
> it's a $20 item, and basically has "on" and "off" settings.
>
> What I do is turn it on and wait.  About 3 minutes later, the solder
> paste starts melting.  It takes about 10-20 seconds for the whole
> board to be done after that, then I slide it off the hotplate onto a
> cooling rack.

I would add a temperature sensor of some kind.

>
> > I notice the CPU is socketed could you please try powering up the
> > board without it.
>
> Without the CPU, the oled won't power up.  You're not supposed to
> apply +12v until you program all the timing parameters, else you burn
> out the OLED cells.
>

Sorry. I had a case once where a microprocessors software loop was
causing noise on the power supply at a very fixed frequency. It was
then picked up and amplified in another area of the board. This is not
uncommon but you eliminated the audio amp.

My only remaining advise is to check anything left with large
transistors. The display and the CPU seem unlikely as places for the
sound come from so I was trying to remove them. Electronic noise
frequently comes from displays but not sound.

-- 
http://www.coe.neu.edu/~efoss/
http://evanfoss.googlepages.com/


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