Elecraft

K3 - No speaker output

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Stewart@twinwood

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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David Honey

Re: K3 - No speaker output

Check that the speakers have not been turned off in the menu. I leave my speakers connected and then use the PF2 key to execute a macro to toggle the speakers setting.

Sent from Samsung Galaxy Note

-------- Original message --------
From: Stewart <[hidden email]>
Date: 14/01/2014 16:36 (GMT+00:00)
To: Elecraft Reflector <[hidden email]>
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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Dave Hachadorian-2

Re: K3 - No speaker output

In reply to this post by Stewart@twinwood

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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Dave Hachadorian-2

Re: K3 - No speaker output

In reply to this post by Stewart@twinwood

Bob,

It's not on the web site. I heard about it indirectly, sent them
an email, got the part number and price, then called up and
ordered two, one for each of my K3's. I haven't installed them
yet.

Dave Hachadorian, K6LL
Yuma, AZ

-----Original Message-----
From: Bob
Sent: Tuesday, January 14, 2014 11:01 AM
To: Dave Hachadorian
Subject: Re: [Elecraft] K3 - No speaker output

Hi Dave,

I just spent about 20 minutes searching for
information on this
mod. I can not find it on the Elecraft site. Do you have a
linkable source or
any PDF , or other format, type documents.

I would certainly order it for that price and have
it on hand for
the next time the K3 gets opened. But would like to know more
before I ordered
it. I've never had an audio issue but, "An ounce of protection
is worth a pound
of cure.".

73,
Bob
K2TK ex KN2TKR (1956) & K2TKR

On 1/14/2014 12:21 PM, 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
>
>

\

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Joe Subich, W4TV-4

Re: K3 - No speaker output

In reply to this post by Dave Hachadorian-2

> Elecraft now has an Audio Protection Assembly circuit board, Part
> Number E850506 for $2.36 plus shipping.

The Audio Protection Assembly replaces the 470 uF output capacitors C2
and C3 on the RF board with a series combination of a 1 Ohm resistor
and 470 uF capacitor. The same thing can be accomplished by replacing
L13 and L16 (surface mounted "beads") on the KIO3 Audio IO Board with
the appropriate size 1 Ohm surface mount resistor (or potentially even
a leaded part). The advantage t modifying the KIO3 Audio IO Board is
that it is not necessary to disassemble the K3 (and remove sub R and/or
2M transverter) to gain access.

Note - the bead to resistor modification is my own adaptation and not
recommended by Elecraft.

73,

... Joe, W4TV

On 1/14/2014 12:21 PM, 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
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
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>
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>

W1KSZ

Re: K3 - No speaker output

In reply to this post by Dave Hachadorian-2

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
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Don Wilhelm-4

Re: K3 - No speaker output

Dick,

If you have an early K3 *and* you plugged a mono connector into the rear
speaker jack, one channel was shorted by the mono connector. That will
cause failure of the audio amp for the speaker.
Later K3s (I don't know the serial number) have protection for that
shorting condition. The best protection is not to put a mono plug into
the speaker jack. If you want mono, cut off the mono plug and connect
only the tip and shell to your speaker - the ring does not connect to
anything.

73,
Don W3FPR

On 1/14/2014 6:55 PM, Richard Solomon wrote:
> Can someone explain to me exactly why the chip failed, and what the Audio
> Protection Assembly is for ?
>
> Tnx, Dick, W1KSZ
>

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Mel

Re: K3 - No speaker output

In reply to this post by W1KSZ

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 <[hidden email]> 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:

Mel

Re: K3 - No speaker output

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 <[hidden email]> 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 <[hidden email]> 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:

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Dave Hachadorian-2

Re: K3 - No speaker output

In reply to this post by Don Wilhelm-4

Putting a mono plug into the stereo jack is not the ONLY failure
mechanism for the speaker amplifier chip. It was not the cause
of failure of my two K3's.

I'm not sure anyone fully understands the failure
mechanisms in the speaker amplifier.

The new $2.36 mod adds 1 ohm resistors in series with the audio
output channels. Hopefully that will do some good.

Dave Hachadorian, K6LL
Yuma, AZ

-----Original Message-----
From: Don Wilhelm
Sent: Tuesday, January 14, 2014 5:10 PM
To: [hidden email]
Subject: Re: [Elecraft] K3 - No speaker output

Dick,

If you have an early K3 *and* you plugged a mono connector into
the rear
speaker jack, one channel was shorted by the mono connector. That
will
cause failure of the audio amp for the speaker.
Later K3s (I don't know the serial number) have protection for
that
shorting condition. The best protection is not to put a mono
plug into
the speaker jack. If you want mono, cut off the mono plug and
connect
only the tip and shell to your speaker - the ring does not
connect to
anything.

73,
Don W3FPR

On 1/14/2014 6:55 PM, Richard Solomon wrote:
> Can someone explain to me exactly why the chip failed, and what
> the Audio
> Protection Assembly is for ?
>
> Tnx, Dick, W1KSZ
>

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Mel

Re: K3 - No speaker output

Sorry, but the only solution to keep the two outputs isolated is to provide two audio output jacks, one for left and one for right. AND have a appropriate limiting coupling cap or series limiting regulator for the amp. IMHO.

Mel, K6KBE

On Tuesday, January 14, 2014 6:13 PM, Dave Hachadorian <[hidden email]> wrote:

Putting a mono plug into the stereo jack is not the ONLY failure
mechanism for the speaker amplifier chip. It was not the cause
of failure of my two K3's.

I'm not sure anyone fully understands the failure
mechanisms in the speaker amplifier.

The new $2.36 mod adds 1 ohm resistors in series with the audio
output channels. Hopefully that will do some good.

Dave Hachadorian, K6LL
Yuma, AZ

-----Original Message-----
From: Don Wilhelm
Sent: Tuesday, January 14, 2014 5:10 PM
To: [hidden email]
Subject: Re: [Elecraft] K3 - No speaker output

Dick,

If you have an early K3 *and* you plugged a mono connector into
the rear
speaker jack, one channel was shorted by the mono connector. That
will
cause failure of the audio amp for the speaker.
Later K3s (I don't know the serial number) have protection for
that
shorting condition. The best protection is not to put a mono
plug into
the speaker jack. If you want mono, cut off the mono plug and
connect
only the tip and shell to your speaker - the ring does not
connect to
anything.

73,
Don W3FPR

On 1/14/2014 6:55 PM, Richard Solomon wrote:
> Can someone explain to me exactly why the chip failed, and what
> the Audio
> Protection Assembly is for ?
>
> Tnx, Dick, W1KSZ
>

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Stewart@twinwood

Re: K3 - No speaker output

In reply to this post by Dave Hachadorian-2

Mine failed with a stereo (not a mono) plug which had been inserted prior to the
K3 being powered on.

The external speaker of 8 ohms was wired onto the left channel (plug tip),
therefore the right channel did not have a load at the time. Don't know if this
causes a problem.

The fault occurred when the AF gain on my K3 was advanced to approx 12 o'clock,
at which point the audio out the speaker failed.

So, the fault was NOT caused by shorting either of the outputs, or plugging in
the speaker with the K3 powered on.

My K3 is an early Ser # 307

73
Stewart G3RXQ

On Tue, 14 Jan 2014 19:10:29 -0700, Dave Hachadorian wrote:

> Putting a mono plug into the stereo jack is not the ONLY failure
> mechanism for the speaker amplifier chip. It was not the cause
> of failure of my two K3's.
>
> I'm not sure anyone fully understands the failure
> mechanisms in the speaker amplifier.
>
> The new $2.36 mod adds 1 ohm resistors in series with the audio
> output channels. Hopefully that will do some good.
>
> Dave Hachadorian, K6LL
> Yuma, AZ
>
>
> -----Original Message-----
> From: Don Wilhelm
> Sent: Tuesday, January 14, 2014 5:10 PM
> To: [hidden email]
> Subject: Re: [Elecraft] K3 - No speaker output
>
> Dick,
>
> If you have an early K3 *and* you plugged a mono connector into
> the rear
> speaker jack, one channel was shorted by the mono connector. That
> will
> cause failure of the audio amp for the speaker.
> Later K3s (I don't know the serial number) have protection for
> that
> shorting condition. The best protection is not to put a mono
> plug into
> the speaker jack. If you want mono, cut off the mono plug and
> connect
> only the tip and shell to your speaker - the ring does not
> connect to
> anything.
>
> 73,
> Don W3FPR
>
> On 1/14/2014 6:55 PM, Richard Solomon wrote:
>> Can someone explain to me exactly why the chip failed, and what
>> the Audio
>> Protection Assembly is for ?
>>
>> Tnx, Dick, W1KSZ
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list:
> http://www.qsl.net/donate.html
>
> ______________________________________________________________
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Bill-3

Re: K3 - No speaker output

Is the improved circuit in production K3s and, if so, at what serial
number did that start?

Bill W2BLC

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wayne burdick

Re: K3 - No speaker output

Administrator

The final addition to the AF amp protection circuitry was phased into production about a year ago. I'm trying to determine what the first S/N was. We'll also be making this available as a mod kit shortly.

There have been a few other improvements to the AF amp circuitry, all phased into production a long time ago. These are listed on the K3 mods page. The K3 owner who posted about not having speaker output has a very old K3 (~S/N 300) which had none of the upgrades. AF amp problems are now exceedingly rare.

73,
Wayne
N6KR

On Jan 15, 2014, at 3:21 AM, Bill W2BLC <[hidden email]> wrote:

> Is the improved circuit in production K3s and, if so, at what serial number did that start?
>
> Bill W2BLC
>
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