Topics

U1 fried

K4LXY
 

Last night while trying various speakers, smoke started rolling out of my uBitx.  The audio IC U1 was fried.  I'm assuming the audio line shorted while inserting plugs.  They are cheap (5 for $6) and I'll install a socket for easy replacement.  But a word of warning.....
Howard K4LXY

Walter
 

On Wed, Feb 28, 2018 at 04:08 am, DrZ wrote:
Last night while trying various speakers, smoke started rolling out of my uBitx.  The audio IC U1 was fried.  I'm assuming the audio line shorted while inserting plugs.  They are cheap (5 for $6) and I'll install a socket for easy replacement.  But a word of warning.....
Howard K4LXY
i Noticed the volume switch has an on/off switch built into it.  perhaps I will connect this in line with the speaker jack and turn it off before plugging and unpluggings speakers and stuff.
 
--
73, W9KJO
Walter

K5ESS
 

It appears at least a few folks have fried U1 by inserting a mono plug in the speaker jack and shorting out the audio.  I’d recommend only wiring up the tip connection and not the ring and then using an external mono to serial adapter for your stereo phones.

Mike

K5ESS

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Walter
Sent: Wednesday, February 28, 2018 6:16 AM
To: BITX20@groups.io
Subject: Re: [BITX20] U1 fried

 

On Wed, Feb 28, 2018 at 04:08 am, DrZ wrote:

Last night while trying various speakers, smoke started rolling out of my uBitx.  The audio IC U1 was fried.  I'm assuming the audio line shorted while inserting plugs.  They are cheap (5 for $6) and I'll install a socket for easy replacement.  But a word of warning.....
Howard K4LXY

i Noticed the volume switch has an on/off switch built into it.  perhaps I will connect this in line with the speaker jack and turn it off before plugging and unpluggings speakers and stuff.
 

--
73, W9KJO
Walter

Jerry Gaffke
 

I assume the mono to serial adapter would just short the mono signal to both stereo signals.
So you are back where you started, plugging a mono jack into that adapter will kill the TDA2822M.
Could work if you avoid this, but not foolproof.  And thus not suitable if I'm anywhere in the vicinity.

Might be better to add a series resistor inside the radio, and/or reduce the supply voltage to the TDA2822M

Jerry, KE7ER


On Wed, Feb 28, 2018 at 09:22 am, K5ESS wrote:

It appears at least a few folks have fried U1 by inserting a mono plug in the speaker jack and shorting out the audio.  I’d recommend only wiring up the tip connection and not the ring and then using an external mono to serial adapter for your stereo phones.

 

K5ESS
 

Yes the mono to stereo adapter does just short the mono signal to both stereo signals but that is not the problem.  The problem is when you insert a mono plug into the uBITX stereo jack it shorts the ring connection (and the output of U1) to ground.  If the ring connection is left open there will be no short when a mono plug is inserted.

Mike

K5ESS

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Jerry Gaffke via Groups.Io
Sent: Wednesday, February 28, 2018 11:36 AM
To: BITX20@groups.io
Subject: Re: [BITX20] U1 fried

 

I assume the mono to serial adapter would just short the mono signal to both stereo signals.
So you are back where you started, plugging a mono jack into that adapter will kill the TDA2822M.
Could work if you avoid this, but not foolproof.  And thus not suitable if I'm anywhere in the vicinity.

Might be better to add a series resistor inside the radio, and/or reduce the supply voltage to the TDA2822M

Jerry, KE7ER


On Wed, Feb 28, 2018 at 09:22 am, K5ESS wrote:

It appears at least a few folks have fried U1 by inserting a mono plug in the speaker jack and shorting out the audio.  I’d recommend only wiring up the tip connection and not the ring and then using an external mono to serial adapter for your stereo phones.

 

K5ESS
 

Jerry,

After re-reading your post I now see your point.  But I think it a lot less likely that someone would plug a mono plug into a mono to stereo adapter IMHO.

Mike

K5ESS

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Jerry Gaffke via Groups.Io
Sent: Wednesday, February 28, 2018 11:36 AM
To: BITX20@groups.io
Subject: Re: [BITX20] U1 fried

 

I assume the mono to serial adapter would just short the mono signal to both stereo signals.
So you are back where you started, plugging a mono jack into that adapter will kill the TDA2822M.
Could work if you avoid this, but not foolproof.  And thus not suitable if I'm anywhere in the vicinity.

Might be better to add a series resistor inside the radio, and/or reduce the supply voltage to the TDA2822M

Jerry, KE7ER


On Wed, Feb 28, 2018 at 09:22 am, K5ESS wrote:

It appears at least a few folks have fried U1 by inserting a mono plug in the speaker jack and shorting out the audio.  I’d recommend only wiring up the tip connection and not the ring and then using an external mono to serial adapter for your stereo phones.

 

Walter
 

So what is the universal fix?  if a mono jack is plugged into a stereo jack on another electronic device it does not destroy the audio output of those devices.

How do they prevent damage on many other devices with stereo jacks?

--
73, W9KJO
Walter

Thomas Sharka
 

I just wired the stereo jack as a mono jack. The signal goes to the tip and the ground goes to the sleeve. The ring isn't connected. Now when I plug in a pair of stereo headphones, I only get one channel, but if I plug in a mono jack, I get sound. When I swap plugs, the short never happens.
 


Sent from Yahoo Mail. Get the app


On Wednesday, February 28, 2018 1:49 PM, Walter <W9KJO@...> wrote:


So what is the universal fix?  if a mono jack is plugged into a stereo jack on another electronic device it does not destroy the audio output of those devices.

How do they prevent damage on many other devices with stereo jacks?

--
73, W9KJO
Walter

Jerry Gaffke
 

Re-read this post:  https://groups.io/g/BITX20/message/42723

Adding a series 8 ohm 1/2 watt resistor between the uBitx board and your phone jack should 
safely prevent any damage, though it will reduce the maximum available audio.

Could be that 4 ohms is sufficient.
 
Jerry


On Wed, Feb 28, 2018 at 10:49 am, Walter wrote:
So what is the universal fix?  if a mono jack is plugged into a stereo jack on another electronic device it does not destroy the audio output of those devices.

How do they prevent damage on many other devices with stereo jacks?

Jerry Gaffke
 

I'm glad that works for you.
But when concocting a recommended solution across thousands of rigs,
we'd best somehow make the rig survive an audio short to ground.   
Or this forum will getting traffic about fried TDA2822M's for years to come.


On Wed, Feb 28, 2018 at 10:55 am, Thomas Sharka wrote:
I just wired the stereo jack as a mono jack. The signal goes to the tip and the ground goes to the sleeve. The ring isn't connected. Now when I plug in a pair of stereo headphones, I only get one channel, but if I plug in a mono jack, I get sound. When I swap plugs, the short never happens.
 
 

John
 

I fried mine when I plugged in a stereo sony noise canceling headset.
So it does not only happen with mono plugs.

Hopefully the spare TDAs with sockets will arrive soon so Incan start troubleshooting my no power problem.
To be on the safe side and avoid another wait I also ordered some IRFs ;)


John

Jerry Gaffke
 

So where did you get your spare TDA2822M's?

The TDA2822M is $7 for two on ebay, quite expensive for what it is.
Mainline distributors like Mouser and Digikey say it's discontinued.
ST no longer makes it, sources may be drying up.

My uBitx has a part on it marked "TDA2822M" but no ST logo, not sure who makes it.

Banggood has this amp, photos show it to be stuffed with a UTC2822H clone, but I'm having no luck finding a source for that chip either.
  https://www.banggood.com/TDA2822M-1W-x-2-Dual-Channel-Audio-Amplifier-Stereo-Module-Board-Volume-Control-p-1067736.html

Someday we might need to find a replacement.
Maybe a little PC board with 8 header pins.
Stuff it with a bunch of mmbt3904's if nothing else.

Curious that the stereo headset fried the TDA2822M.
Perhaps it presented too low an impedance when first plugged in for some reason? 

Not at all clear from the datasheet that the TDA2822M will survive a 4 ohm speaker
when powered from a 12v+ supply.

Jerry, KE7ER


On Wed, Feb 28, 2018 at 02:22 pm, John wrote:
I fried mine when I plugged in a stereo sony noise canceling headset.
So it does not only happen with mono plugs.

Hopefully the spare TDAs with sockets will arrive soon so Incan start troubleshooting my no power problem.
To be on the safe side and avoid another wait I also ordered some IRFs ;)

John
 

I ordered them from China, but on eBay I found an US seller with the TDA2822L. Specs seemed to be similar.

Maybe I was to slow plugging the headset I.

John

Clark Martin
 

The TDA2822M data sheet lists an absolute maximum one amp output output current.  Since this chip is apparently prone to blowing out on short circuit I would add a .5A fast blow fuse in the speaker line, between the PCB and the headphone jack.  It doesn’t need a fuse holder, it could be soldered in (using a fuse with pigtail leads).  It would still be easier and cheaper to replace than the amp IC.

I’ll likely add this mod to my µBitx.  I don’t intend to short it out but then almost no one does.


Clark Martin
KK6ISP

On Feb 28, 2018, at 2:22 PM, John <jjczon@...> wrote:

I fried mine when I plugged in a stereo sony noise canceling headset.
So it does not only happen with mono plugs.

Hopefully the spare TDAs with sockets will arrive soon so Incan start troubleshooting my no power problem.
To be on the safe side and avoid another wait I also ordered some IRFs ;)

Jerry Gaffke
 

Better be a pretty darn fast fuse.

I'll go with an 8 ohm 1/2 watt series resistor to limit current.
At least till I find a good source for TDA2822M chips.
I'm fairly certain that resistor will offer sufficient protection.

Jerry


On Wed, Feb 28, 2018 at 03:51 pm, Clark Martin wrote:
The TDA2822M data sheet lists an absolute maximum one amp output output current.  Since this chip is apparently prone to blowing out on short circuit I would add a .5A fast blow fuse in the speaker line, between the PCB and the headphone jack.  It doesn’t need a fuse holder, it could be soldered in (using a fuse with pigtail leads).  It would still be easier and cheaper to replace than the amp IC.
 
I’ll likely add this mod to my µBitx.  I don’t intend to short it out but then almost no one does.
 
 

Clark Martin
 

The TDA2822D in effect replaces the “M” version.  It appears the same except it’s an SMD part.  You can get SMD to through hole adapter boards that would let you use one with the µBitX.  It would likely be cheaper than buying the “M” version.

An example of the adapter board:


And plug headers to plug them into an IC socket (or solder in).




Clark Martin
KK6ISP

On Feb 28, 2018, at 2:49 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

So where did you get your spare TDA2822M's?

The TDA2822M is $7 for two on ebay, quite expensive for what it is.
Mainline distributors like Mouser and Digikey say it's discontinued.
ST no longer makes it, sources may be drying up.

My uBitx has a part on it marked "TDA2822M" but no ST logo, not sure who makes it.

Clark Martin
 

The chip is rated to work with a 4Ω load so a 4Ω resistor should do. I doubt the chip would blow so fast that FB fuse wouldn’t protect it.


Clark Martin
KK6ISP

On Feb 28, 2018, at 4:00 PM, Jerry Gaffke via Groups.Io <jgaffke=yahoo.com@groups.io> wrote:

Better be a pretty darn fast fuse.

I'll go with an 8 ohm 1/2 watt series resistor to limit current.
At least till I find a good source for TDA2822M chips.
I'm fairly certain that resistor will offer sufficient protection.

Jerry Gaffke
 

Ah, the TDA82822D part in the SOIC8 package is a good find.
Feeling much better now!

Digikey has it for a bit over a dollar (Mouser says a minimum buy of 2000).
Maybe hfsignals will move to the more easily gotten SMD part if they ever roll the board.
Though I'm pretty sure I could solder the SMD into place with just some short wires,
not bothering with the adapter board.

> The chip is rated to work with a 4Ω load so a 4Ω resistor should do. I doubt the chip would blow so fast that FB fuse wouldn’t protect it.

Yes, I think a 4 ohm resistor would probably do, I was getting rather cautious when I saw how hard the M part was to obtain.
I'm suspicious that with a 12v supply it is close to the edge, they seem to blow with little provocation.
Most of the datasheet seems to assume a max of 9v.
The fact that it works down to 1.8v reinforces this notion.

The fuse might protect it, depends on the failure mode.
The fuse costs about as much as the TDA2822D.

Jerry


On Wed, Feb 28, 2018 at 04:02 pm, Clark Martin wrote:
The TDA2822D in effect replaces the “M” version.  It appears the same except it’s an SMD part.  You can get SMD to through hole adapter boards that would let you use one with the µBitX.  It would likely be cheaper than buying the “M” version.
 
 

Allard PE1NWL
 

NJM2073D seems to be a replacement for TDA2822, price is about one dollar:

http://mklec.com/components/integrated-circuit/op-amps/jrc-njm2073d-stereo-audio-power-amplifier

73 Allard PE1NWL

On Thu, March 1, 2018 01:45, Jerry Gaffke via Groups.Io wrote:
Ah, the TDA82822D part in the SOIC8 package is a good find.
Feeling much better now!

Digikey has it for a bit over a dollar (Mouser says a minimum buy of
2000).
Maybe hfsignals will move to the more easily gotten SMD part if they ever
roll the board.
Though I'm pretty sure I could solder the SMD into place with just some
short wires,
not bothering with the adapter board.

The chip is rated to work with a 4Ω load so a 4Ω resistor should do. I
doubt the chip would blow so fast that FB fuse wouldn’t protect it.
Yes, I think a 4 ohm resistor would probably do, I was getting rather
cautious when I saw how hard the M part was to obtain.
I'm suspicious that with a 12v supply it is close to the edge, they seem
to blow with little provocation.
Most of the datasheet seems to assume a max of 9v.
The fact that it works down to 1.8v reinforces this notion.

The fuse might protect it, depends on the failure mode.
The fuse costs about as much as the TDA2822D.

Jerry

On Wed, Feb 28, 2018 at 04:02 pm, Clark Martin wrote:


The TDA2822D in effect replaces the “M� version.  It appears the
same
except it’s an SMD part.  You can get SMD to through hole adapter
boards
that would let you use one with the µBitX.  It would likely be cheaper
than buying the “M� version.
 
 

K5ESS
 

Tayda has the TDA2822L for $0.29 each with 126,973 available.  It’s an 8 pin DIP.  Didn’t see any glaring differences looking at the data sheets but another pair of eyes might see something.  Also I noticed that the datasheets show power outputs with a 4 ohm load with a max Vcc of 6 volts so a 4 ohm resistor might not provide protection with a Vcc of 12 volts.

Mike

K5ESS

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Clark Martin
Sent: Wednesday, February 28, 2018 6:03 PM
To: BITX20@groups.io
Subject: Re: [BITX20] U1 fried

 

The TDA2822D in effect replaces the “M” version.  It appears the same except it’s an SMD part.  You can get SMD to through hole adapter boards that would let you use one with the µBitX.  It would likely be cheaper than buying the “M” version.

 

An example of the adapter board:

 

 

And plug headers to plug them into an IC socket (or solder in).

 

 

 

 

Clark Martin

KK6ISP

 

On Feb 28, 2018, at 2:49 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

 

So where did you get your spare TDA2822M's?

The TDA2822M is $7 for two on ebay, quite expensive for what it is.
Mainline distributors like Mouser and Digikey say it's discontinued.
ST no longer makes it, sources may be drying up.

My uBitx has a part on it marked "TDA2822M" but no ST logo, not sure who makes it.