[Elecraft] K3 Speaker Amp - sub side inop

[Pete Smith]

Some of the SMT tutorials on the Internet show ways of using fine-gauge 
rosin solder or solder paste to solder these ICs - essentially, they 
tell you to rely on surface tension and the natural bond of the solder 
to the pads, literally pulling the solder away from a shorted condition 
to pool on the individual pads.  In fact, one tutorial I viewed shows 
actually laying down a "worm" of solder paste bridging all the terminals 
on one side of a chip and then applying heat with an embosssing gun - a 
scaled-down heat gun.  As soon as the solder goes liquid it draws back 
to the pads.  Might be worth trying, though I admit I chickened out when 
it came to trying to replace the RS-232 transceiver on my KIO3.

73, Pete N4ZR

The World Contest Station Database, updated daily at www.conteststations.com
The Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com,
spots at telnet.reversebeacon.net, port 7000


On 8/27/2010 3:47 PM, Dave Hachadorian wrote:
>>> Any ideas are welcome.  Meanwhile, is the LM4950TS stereo amp
>>> available as a component from Elecraft, and is it
>>> user-repairable?
>>>        
> That chip is fragile. I've blown it twice, just with excessively
> loud audio. (AGC OFF)
>
> I'm a fairly good solderer, and I bought a replacement IC here:
> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=LM4950TS-ND
>
> I was able to remove the old chip by cutting all the leads, and
> removing them one by one, but when I looked at the tiny pads on
> the circuit board, I chickened out. I couldn't see any way to
> solder those pins to the pads without shorting them to each
> other. They are EXTREMELY close together.
>
> I ended up sending the DSP Board back to Elecraft for repair.
>
> Dave Hachadorian, K6LL
> Big Bear Lake, CA
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> .
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>
>