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Hi Group:
I am getting no audio out of my ubitX and have tried the suggestions posted here in another string.
1)? RX has +12V at R18 & R38.
2) TX is low at R28 and R40
3)? I have tried SPH out direct to an 8 h\ohm speaker with no results
4)? I M1 to Vol-M with no results.
I have checked voltage to the TDA8222 chip and VCC is present.
Still, no audio whatsoever.
I have the uBit-X schematic, and have a scope, signal generator and signal tracer, and am wondering if test point voltages and wave forms might be posted somewhere??
Has any collected this information and where I can access it?
Thanks in advance.
- andy, KD3RF / VE2DXY
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I will be following with interest.??
I managed to trust the connector wiring of the power wire loom, and should have not, as it had power and ground reversed at the connector, and I shot reverse polarity into the works.? Transmit works, Raduino Works, but no audio.??
Hopefully I will be able to repair.? It is gonna push my sight, eye-hand coordination, and desoldering/soldering skills to replace SMDs, but I'm game for a good try.??
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Andy
See if you have sidetone when using cw. If you don't have a key, you still need that external 4.7k resistor anyway. Then put a short across the key input to listen for sidetone audio. If none, possibly the audio amp ic is defective, a common v3 malady I am told. Also you can inject audio into its input to see if this is the issue.
If this is the problem, I would be so tempted to not repair it, but use another audio amp board. V3 folk can chime in, or search here for v3 audio.
Curt
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The only problem with the audio amp on the v3 boards was that
they had a run of bad TDA2822 clone chips.
The TDA2822's with a "WX" marking may (or may not) fail when powered from 12v,
if you catch it before it blows you can add a voltage regulator to feed it only 6v or so and it will be fine.
As far as I know, nobody ever had other than the "WX" marked parts fail.
If a WX does fail, I'd suggest you replace it with an?NJM2073D (identical pinout and function), costs about $1 US.
Other TDA2822's from hfsignals (mostly marked "FCI") work fine with no mods required.
The v4 boards replaced the TDA2822's with an 2n3904/2n3906 push-pull pair.
But that suffers from low volume and often lots of crossover distortion.
Lots of little LM386 amplifier modules out there for $1 US if you don't want to mess with chips,
should work fine as a replacement of the final audio amp on either v3 or v4.
? ??
Wire the input to that module from VOL-M on the uBitx volume control pot and feed the LM386 12v.
You'll want the 1uF (or so) cap between LM386 pins 1 and 8 to boost the gain up from 20dB to 40dB.
Should wind up with something very much like the LM386 audio amp on the Bitx40.
Jerry, KE7ER
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Show quoted text
On Tue, Jan 22, 2019 at 02:24 PM, Curt wrote:
Andy
See if you have sidetone when using cw. If you don't have a key, you still need that external 4.7k resistor anyway. Then put a short across the key input to listen for sidetone audio. If none, possibly the audio amp ic is defective, a common v3 malady I am told. Also you can inject audio into its input to see if this is the issue.
If this is the problem, I would be so tempted to not repair it, but use another audio amp board. V3 folk can chime in, or search here for v3 audio.
Curt
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Jerry,
I have had some non-WX chips fail at loud levels.
Raj
At 23-01-19, you wrote:
toggle quoted message
Show quoted text
The only problem with the audio
amp on the v3 boards was that
they had a run of bad TDA2822 clone chips.
The TDA2822's with a "WX" marking may (or may not) fail when
powered from 12v,
if you catch it before it blows you can add a voltage regulator to feed
it only 6v or so and it will be fine.
As far as I know, nobody ever had other than the "WX" marked
parts fail.
If a WX does fail, I'd suggest you replace it with an NJM2073D (identical
pinout and function), costs about $1 US.
Other TDA2822's from hfsignals (mostly marked "FCI") work fine
with no mods required.
The v4 boards replaced the TDA2822's with an 2n3904/2n3906 push-pull
pair.
But that suffers from low volume and often lots of crossover
distortion.
Lots of little LM386 amplifier modules out there for $1 US if you don't
want to mess with chips,
should work fine as a replacement of the final audio amp on either v3 or
v4.
???
Wire the input to that module from VOL-M on the uBitx volume control pot
and feed the LM386 12v.
You'll want the 1uF (or so) cap between LM386 pins 1 and 8 to boost the
gain up from 20dB to 40dB.
Should wind up with something very much like the LM386 audio amp on the
Bitx40.
Jerry, KE7ER
|
The TDA2822 should not have failed but for two reasons explained by many. I am just recapitulating them. 1. Stereo out jack with mono earphone or external speaker plugged. This situation created short at the amplifier output. 2. using the device at its extreme working voltage. See anywhere, you find that this device is used only at 3 or? 6V. ?Solutions where implemented , the devices should be working even now.
regards sarma?? vu3zmv
Jerry,
I have had some non-WX chips fail at loud levels.
Raj
At 23-01-19, you wrote:
The only problem with the audio
amp on the v3 boards was that
they had a run of bad TDA2822 clone chips.
The TDA2822's with a "WX" marking may (or may not) fail when
powered from 12v,
if you catch it before it blows you can add a voltage regulator to feed
it only 6v or so and it will be fine.
As far as I know, nobody ever had other than the "WX" marked
parts fail.
If a WX does fail, I'd suggest you replace it with an NJM2073D (identical
pinout and function), costs about $1 US.
Other TDA2822's from hfsignals (mostly marked "FCI") work fine
with no mods required.
The v4 boards replaced the TDA2822's with an 2n3904/2n3906 push-pull
pair.
But that suffers from low volume and often lots of crossover
distortion.
Lots of little LM386 amplifier modules out there for $1 US if you don't
want to mess with chips,
should work fine as a replacement of the final audio amp on either v3 or
v4.
???
Wire the input to that module from VOL-M on the uBitx volume control pot
and feed the LM386 12v.
You'll want the 1uF (or so) cap between LM386 pins 1 and 8 to boost the
gain up from 20dB to 40dB.
Should wind up with something very much like the LM386 audio amp on the
Bitx40.
Jerry, KE7ER
|
OK, thanks to Raj for clarifying this.
I remember him reporting the non-WX TDA2822 could get remarkably hot
when driving a low impedance speaker with lots of audio,
did not recall it blowing.
Several solutions for this, any should work on non-WX TDA2822's:??
? Put your finger on the TDA2822 when trying high volume levels, back off if it gets uncomfortably hot (over 60C).
? Add a resistor of 10 or 20 ohms in series with your low impedance (4 ohm?) speaker.
? Add a voltage regulator to supply less than 12v to the TDA2822
When the TDA2822's first started blowing, we were all scratching our heads as to why.
Were several reports of having it blow the moment headphones or speaker got plugged into the rig
Eventually we figured out that the parts that were blowing were marked "WX" not "FCI",
and that the momentary short put them over the edge.? ?In many cases the "WX" parts
blew spontaneously and not at high volume, these clones simply can't deal with 12v.
There are web reports of other TDA2822 clones that fail miserably at anything much over 6v.
The original TDA2822 from ST (and NJR's?NJM2073D) is?rated for an absolute max voltage of 15v,
a max working voltage of 12v, though being a linear class AB amp will dissipate as much power in heat
as it gives in audio to the speaker.? Operating at 12v, it is possible to exceed the max
dissipation rating if you crank up the volume, and the chip will slowly heat up.
A momentary short at the headphone jack should not blow a quality TDA2822,
it would?take time for the heat to build up enough to destroy it.
Though to be safe, not a bad idea to avoid shorts.
I have an FCI marked TDA2822 on my v3 uBitx, I have not bothered with any fixes.
Though I'm not trying to fill the house with the music of shortwave radio,
as not everyone here finds it quite so musical.
Jerry, KE7ER
On Tue, Jan 22, 2019 at 09:54 PM, Raj vu2zap wrote:
I have had some non-WX chips fail at loud levels.?
On Tue, Jan 22, 2019 at 10:19 PM, MVS Sarma wrote:
The TDA2822 should not have failed but for two reasons explained by many. I am just recapitulating them.
1. Stereo out jack with mono earphone or external speaker plugged. This situation created short at the amplifier output.
2. using the device at its extreme working voltage. See anywhere, you find that this device is used only at 3 or? 6V.
?Solutions where implemented , the devices should be working even now.
?
|
I did fry a non wx tda when I first assembled the boards and the volume potentiometer connections were reversed. Rewiring correctly and replacing it solved the problem. I haven't added the voltage regulator. Using an 8 ohm speaker I had no other issue. The tda is quite powerful for me and would use at low volume.
Il 23/gen/2019 17:16, "Jerry Gaffke via Groups.Io" <jgaffke= [email protected]> ha scritto: OK, thanks to Raj for clarifying this.
I remember him reporting the non-WX TDA2822 could get remarkably hot
when driving a low impedance speaker with lots of audio,
did not recall it blowing.
Several solutions for this, any should work on non-WX TDA2822's:??
? Put your finger on the TDA2822 when trying high volume levels, back off if it gets uncomfortably hot (over 60C).
? Add a resistor of 10 or 20 ohms in series with your low impedance (4 ohm?) speaker.
? Add a voltage regulator to supply less than 12v to the TDA2822
When the TDA2822's first started blowing, we were all scratching our heads as to why.
Were several reports of having it blow the moment headphones or speaker got plugged into the rig
Eventually we figured out that the parts that were blowing were marked "WX" not "FCI",
and that the momentary short put them over the edge.? ?In many cases the "WX" parts
blew spontaneously and not at high volume, these clones simply can't deal with 12v.
There are web reports of other TDA2822 clones that fail miserably at anything much over 6v.
The original TDA2822 from ST (and NJR's?NJM2073D) is?rated for an absolute max voltage of 15v,
a max working voltage of 12v, though being a linear class AB amp will dissipate as much power in heat
as it gives in audio to the speaker.? Operating at 12v, it is possible to exceed the max
dissipation rating if you crank up the volume, and the chip will slowly heat up.
A momentary short at the headphone jack should not blow a quality TDA2822,
it would?take time for the heat to build up enough to destroy it.
Though to be safe, not a bad idea to avoid shorts.
I have an FCI marked TDA2822 on my v3 uBitx, I have not bothered with any fixes.
Though I'm not trying to fill the house with the music of shortwave radio,
as not everyone here finds it quite so musical.
Jerry, KE7ER
On Tue, Jan 22, 2019 at 09:54 PM, Raj vu2zap wrote:
I have had some non-WX chips fail at loud levels.?
On Tue, Jan 22, 2019 at 10:19 PM, MVS Sarma wrote:
The TDA2822 should not have failed but for two reasons explained by many. I am just recapitulating them.
1. Stereo out jack with mono earphone or external speaker plugged. This situation created short at the amplifier output.
2. using the device at its extreme working voltage. See anywhere, you find that this device is used only at 3 or? 6V.
?Solutions where implemented , the devices should be working even now.
?
|
Glue on a heatsink, although this will solve all problems,? it helps.
On Wed, 23 Jan. 2019, 18:16 Jerry Gaffke via Groups.Io <jgaffke= [email protected] wrote: OK, thanks to Raj for clarifying this.
I remember him reporting the non-WX TDA2822 could get remarkably hot
when driving a low impedance speaker with lots of audio,
did not recall it blowing.
Several solutions for this, any should work on non-WX TDA2822's:??
? Put your finger on the TDA2822 when trying high volume levels, back off if it gets uncomfortably hot (over 60C).
? Add a resistor of 10 or 20 ohms in series with your low impedance (4 ohm?) speaker.
? Add a voltage regulator to supply less than 12v to the TDA2822
When the TDA2822's first started blowing, we were all scratching our heads as to why.
Were several reports of having it blow the moment headphones or speaker got plugged into the rig
Eventually we figured out that the parts that were blowing were marked "WX" not "FCI",
and that the momentary short put them over the edge.? ?In many cases the "WX" parts
blew spontaneously and not at high volume, these clones simply can't deal with 12v.
There are web reports of other TDA2822 clones that fail miserably at anything much over 6v.
The original TDA2822 from ST (and NJR's?NJM2073D) is?rated for an absolute max voltage of 15v,
a max working voltage of 12v, though being a linear class AB amp will dissipate as much power in heat
as it gives in audio to the speaker.? Operating at 12v, it is possible to exceed the max
dissipation rating if you crank up the volume, and the chip will slowly heat up.
A momentary short at the headphone jack should not blow a quality TDA2822,
it would?take time for the heat to build up enough to destroy it.
Though to be safe, not a bad idea to avoid shorts.
I have an FCI marked TDA2822 on my v3 uBitx, I have not bothered with any fixes.
Though I'm not trying to fill the house with the music of shortwave radio,
as not everyone here finds it quite so musical.
Jerry, KE7ER
On Tue, Jan 22, 2019 at 09:54 PM, Raj vu2zap wrote:
I have had some non-WX chips fail at loud levels.?
On Tue, Jan 22, 2019 at 10:19 PM, MVS Sarma wrote:
The TDA2822 should not have failed but for two reasons explained by many. I am just recapitulating them.
1. Stereo out jack with mono earphone or external speaker plugged. This situation created short at the amplifier output.
2. using the device at its extreme working voltage. See anywhere, you find that this device is used only at 3 or? 6V.
?Solutions where implemented , the devices should be working even now.
?
--
Adrian
VK2ALF
Cooma, Australia & Otep??, Estonia
|
Oops? Not solve all problems......
Glue on a heatsink, although this will solve all problems,? it helps.
On Wed, 23 Jan. 2019, 18:16 Jerry Gaffke via Groups.Io <jgaffke= [email protected] wrote: OK, thanks to Raj for clarifying this.
I remember him reporting the non-WX TDA2822 could get remarkably hot
when driving a low impedance speaker with lots of audio,
did not recall it blowing.
Several solutions for this, any should work on non-WX TDA2822's:??
? Put your finger on the TDA2822 when trying high volume levels, back off if it gets uncomfortably hot (over 60C).
? Add a resistor of 10 or 20 ohms in series with your low impedance (4 ohm?) speaker.
? Add a voltage regulator to supply less than 12v to the TDA2822
When the TDA2822's first started blowing, we were all scratching our heads as to why.
Were several reports of having it blow the moment headphones or speaker got plugged into the rig
Eventually we figured out that the parts that were blowing were marked "WX" not "FCI",
and that the momentary short put them over the edge.? ?In many cases the "WX" parts
blew spontaneously and not at high volume, these clones simply can't deal with 12v.
There are web reports of other TDA2822 clones that fail miserably at anything much over 6v.
The original TDA2822 from ST (and NJR's?NJM2073D) is?rated for an absolute max voltage of 15v,
a max working voltage of 12v, though being a linear class AB amp will dissipate as much power in heat
as it gives in audio to the speaker.? Operating at 12v, it is possible to exceed the max
dissipation rating if you crank up the volume, and the chip will slowly heat up.
A momentary short at the headphone jack should not blow a quality TDA2822,
it would?take time for the heat to build up enough to destroy it.
Though to be safe, not a bad idea to avoid shorts.
I have an FCI marked TDA2822 on my v3 uBitx, I have not bothered with any fixes.
Though I'm not trying to fill the house with the music of shortwave radio,
as not everyone here finds it quite so musical.
Jerry, KE7ER
On Tue, Jan 22, 2019 at 09:54 PM, Raj vu2zap wrote:
I have had some non-WX chips fail at loud levels.?
On Tue, Jan 22, 2019 at 10:19 PM, MVS Sarma wrote:
The TDA2822 should not have failed but for two reasons explained by many. I am just recapitulating them.
1. Stereo out jack with mono earphone or external speaker plugged. This situation created short at the amplifier output.
2. using the device at its extreme working voltage. See anywhere, you find that this device is used only at 3 or? 6V.
?Solutions where implemented , the devices should be working even now.
?
--
Adrian
VK2ALF
Cooma, Australia & Otep??, Estonia
--
Adrian
VK2ALF
Cooma, Australia & Otep??, Estonia
|
I do not have a momentary short on my audio jack as the ring (the middle connector is not wired to anything. I do not expect to ever listen to stereo on the frequencies this covers and so I just left it unused. I did not install aitcraft landing lights on my van, either <evil grin>.
Meanwhile I have long been in the habit of not plugging-unplugging my radio gear while it is powered. Even some legacy gear balks at that. I have the V3 uBitx with the non-WX chip and everything is happy.
73,
Bill KU8H
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Show quoted text
On 1/23/19 11:16 AM, Jerry Gaffke via Groups.Io wrote: OK, thanks to Raj for clarifying this.
I remember him reporting the non-WX TDA2822 could get remarkably hot
when driving a low impedance speaker with lots of audio,
did not recall it blowing.
Several solutions for this, any should work on non-WX TDA2822's:
? Put your finger on the TDA2822 when trying high volume levels, back off if it gets uncomfortably hot (over 60C).
? Add a resistor of 10 or 20 ohms in series with your low impedance (4 ohm?) speaker.
? Add a voltage regulator to supply less than 12v to the TDA2822
When the TDA2822's first started blowing, we were all scratching our heads as to why.
Were several reports of having it blow the moment headphones or speaker got plugged into the rig
Eventually we figured out that the parts that were blowing were marked "WX" not "FCI",
and that the momentary short put them over the edge.? ?In many cases the "WX" parts
blew spontaneously and not at high volume, these clones simply can't deal with 12v.
There are web reports of other TDA2822 clones that fail miserably at anything much over 6v.
The original TDA2822 from ST (and NJR's NJM2073D) is?rated for an absolute max voltage of 15v,
a max working voltage of 12v, though being a linear class AB amp will dissipate as much power in heat
as it gives in audio to the speaker.? Operating at 12v, it is possible to exceed the max
dissipation rating if you crank up the volume, and the chip will slowly heat up.
A momentary short at the headphone jack should not blow a quality TDA2822,
it would?take time for the heat to build up enough to destroy it.
Though to be safe, not a bad idea to avoid shorts.
I have an FCI marked TDA2822 on my v3 uBitx, I have not bothered with any fixes.
Though I'm not trying to fill the house with the music of shortwave radio,
as not everyone here finds it quite so musical.
Jerry, KE7ER
On Tue, Jan 22, 2019 at 09:54 PM, Raj vu2zap wrote:
I have had some non-WX chips fail at loud levels. On Tue, Jan 22, 2019 at 10:19 PM, MVS Sarma wrote:
The TDA2822 should not have failed but for two reasons explained by
many. I am just recapitulating them.
1. Stereo out jack with mono earphone or external speaker plugged.
This situation created short at the amplifier output.
2. using the device at its extreme working voltage. See anywhere,
you find that this device is used only at 3 or? 6V.
?Solutions where implemented , the devices should be working even now.
--
bark less - wag more
|
If you happen to have only stuff with mono plugs and sockets lying about, that's a good solution.
But all new headphones these days are stereo, so you might need an adapter to go from mono to stereo somewhere.
And if you then plug one of them mono cords into the adapter, we're back to where we started with a short to ground.
Maybe best to just make sure there isn't anything with a mono 3.5mm plug on it within easy reach.
Easy for me, anything I've bought in the last 40 years has been stereo;
?
If you do want to hot-plug headphones into a uBitx and are concerned about a possible
momentary short for some reason, could add a 4 ohm resistor between the uBitx main board and the headphone jack.
Jerry, KE7ER
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Show quoted text
On Wed, Jan 23, 2019 at 10:20 AM, Bill Cromwell wrote:
I do not have a momentary short on my audio jack as the ring (the middle connector is not wired to anything. I do not expect to ever listen to stereo on the frequencies this covers and so I just left it unused. I did not install aitcraft landing lights on my van, either <evil grin>.
Meanwhile I have long been in the habit of not plugging-unplugging my radio gear while it is powered. Even some legacy gear balks at that. I have the V3 uBitx with the non-WX chip and everything is happy.
|
Jerry
How I get around the mono/stereo problems is to wire the headphone jack onto the two end posts only. I let the base float. Stereo headphones are in essence wired in series. monaural works the same with the end and second making the necessary contacts. This means I have to isolate the base from ground but it works well.
73
Dave
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Perhaps Bill's point was that pushing a stereo plug into a stereo jack
can somehow momentarily short one of the signals to ground.
A 4 ohm resistor between uBitx main board and the headphone jack would solve this
if that's of concern.
But I think all cases of momentary shorts blowing a TDA2822 involved a WX brand TDA2822.
We'll see if Raj corrects me on this one too.
Jerry, KE7ER
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Show quoted text
On Wed, Jan 23, 2019 at 12:41 PM, Jerry Gaffke wrote:
Maybe best to just make sure there isn't anything with a mono 3.5mm plug on it within easy reach.
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one can plug in the headphones before switching on and never use more than 10% or so of the volume control,and the chances of chip burning would be reduced.
I recollect , people are accustomed to13.8V, later think that 14 or 14.5 is marginally small.
we fail to understand the stress taken by TDA2822
On Thu, Jan 24, 2019 at 3:28 AM Jerry Gaffke via Groups.Io <jgaffke= [email protected]> wrote: Perhaps Bill's point was that pushing a stereo plug into a stereo jack
can somehow momentarily short one of the signals to ground.
A 4 ohm resistor between uBitx main board and the headphone jack would solve this
if that's of concern.
But I think all cases of momentary shorts blowing a TDA2822 involved a WX brand TDA2822.
We'll see if Raj corrects me on this one too.
Jerry, KE7ER
On Wed, Jan 23, 2019 at 12:41 PM, Jerry Gaffke wrote:
Maybe best to just make sure there isn't anything with a mono 3.5mm plug on it within easy reach.
|
?I did a quick search for LM386 audio amps and came up with this one. ? ?the more you buy, the lower unit price gets. ?Not a bad deal, with free shipping.
?I think it'll cost me a bit more to assemble such an item, even though I have a boatload of LM386 chips.
?its the caps and control, plus board that makes it that way.
?Though doing my own, I can set the gain from 20 to 100, and in between of course.A reasonable board to add audio if yours is blown....
|
Hi, Apparently this in reference to my comments. I doubt a stereo (three conductor) plug will short any signal to ground when plugged into a properly wired stereo jack. A mono (two conductor plug) will short the ring contact in a stereo jack to ground and not just momentarily. In my radios any stereo jack in use for output has it's ring connector *ignored*. Nothing is connected there to short to ground even though the sleeve on the mono plug (grounded) is connected to the ring contact inside the stereo jack. I hope that was wordy enough to be clear. As stated, I do not expect to listen to any stereo on the HF bands and see no point in wiring that contact in the jack. If you bought stereo cans well that is your own personal problem. Put those with your stereo set and use mono on your communications radios. Or listen in one ear. Or rewire the cans as appropriate. I have been down the one ear route when the only thing handy was stereo cans. Somehow I actually survived that until I could get my hands on the mono cans. 73, Bill KU8H On 1/23/19 4:58 PM, Jerry Gaffke via Groups.Io wrote: Perhaps Bill's point was that pushing a stereo plug into a stereo jack
can somehow momentarily short one of the signals to ground.
A 4 ohm resistor between uBitx main board and the headphone jack would solve this
if that's of concern. ---snip----- Jerry, KE7ER
On Wed, Jan 23, 2019 at 12:41 PM, Jerry Gaffke wrote:
Maybe best to just make sure there isn't anything with a mono 3.5mm
plug on it within easy reach.
-- bark less - wag more
|
Neat little amp,? works great, if you don’t mind waiting 5 – 6 weeks for the mail man.
?
Sent from for Windows 10
?
toggle quoted message
Show quoted text
?I did a quick search for LM386 audio amps and came up with this one.
?
?the more you buy, the lower unit price gets.
?Not a bad deal, with free shipping.
?I think it'll cost me a bit more to assemble such an item, even though I have a boatload of LM386 chips.
?its the caps and control, plus board that makes it that way.
?Though doing my own, I can set the gain from 20 to 100, and in between of course.A reasonable board to add audio if yours is blown....
|
Raj vu2zap
Adrian
_Dave_ AD0B