[Elecraft] K3 - No speaker output

[Richard Solomon]

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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