[Elecraft] K3 - No speaker output

[Mel Farrer]

Simpiliar is to not plug anything in to the K3 while it is powered on...........

Mel, K6KBE





On Tuesday, January 14, 2014 5:07 PM, Mel Farrer <farrerfolks at yahoo.com> wrote:
 
I am sure there will be several responses, but when you insert a mono plug into the ext speaker receptacle while the K3 is energized the "chance"of shorting out the stereo output causes an overload and the chip may "fail".  Mine failed as I inserted a mono plug into the stereo speaker jack.  The configuration of the mono plug when inserted into a stereo jack can momentarily short the two channels causing the potential overload.  I use the phone jack now for external audio use.  In the simplest situation, only do configurations of external connections with the K3 turned OFF.  Enf said.

Mel, K6KBE





On Tuesday, January 14, 2014 4:51 PM, Richard Solomon <w1ksz at earthlink.net> wrote:

Can someone explain to me exactly why the chip failed, and what the Audio
Protection Assembly is for ?

Tnx, Dick, W1KSZ


On 1/14/2014 10:21 AM, Dave Hachadorian wrote:
> The speaker amp is U1 on the DSP Board.  The IC is an LM4950TS. The 
> pins are very closely spaced, too close for me.
>
> Elecraft now has an Audio Protection Assembly circuit board, Part 
> Number E850506 for $2.36 plus shipping.
>
> Dave Hachadorian, K6LL
> Yuma, AZ
>
>
>
> -----Original Message----- From: Stewart
> Sent: Tuesday, January 14, 2014 9:36 AM
> To: Elecraft Reflector
> Subject: [Elecraft] K3 - No speaker output
>
> My K3's speaker audio seems to have gone West. Audio out of the 
> phones, but
> nothing out of the internal speaker.
>
> It happened when I was installing a new external speaker, a DSP 
> Desktop speaker
> from BHI.
>
> Having read some recent posts about the audio chip blowing up because 
> of using a
> mono plug instead of a stereo one, I made sure that I used a the 
> correct one.
>
> Following guidance in the K3 users manual I connected the speaker to 
> the LH
> channel as I want to use my headset in stereo.
>
> I also took the covers off and checked for the modification involving 
> 470ohm
> resistors. That mod was in place OK.
>
> I switched the K3 and the speaker on and got audio from the speaker. 
> However,
> when I advanced the AF gain on the K3 to about 12 o'clock there was a 
> pop and no
> more speaker audio from the K3.
>
> I have checked the BHI speaker with another rig and it works fine, so 
> my K3 has
> developed a fault.
>
> I can't believe how sensitive it is to damage in the audio output, 
> particularly
> with the care I took to try and avoid this sort of thing happening....
>
> As I am quite OK with SMD's I would appreciate advice on what to 
> change, where
> to get it and how...
>
> Not a happy bunny !
>
> 73
> Stewart G3RXQ
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