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Micro BitX No Audio TDA2822?
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Ron Thomas
Ok, I am new to this group and have just assembled my micro bitx.? I sent an earlier message to the group explaining that I have no audio.? After reading some of the posts regarding the TDA2822 chip, is it possible that I have somehow blown the audio amp while plugging in headphones or external speaker using the supplied audio jack? I've not heard any noise from the speaker or headphones at any time... no pops or other noises at all. The rig powers up and appears to tune just fine (I haven't tried to transmit yet) but after not getting any audio, I stopped at that point. Where should I probe with voltmeter or oscope to see where I'm losing audio?? Any troubleshooting tips anyone could share would be most appreciated. Is there a schematic of the board somewhere that I can download? Sorry for all the questions but I don't know much about this rig. 73, Ron N4RT |
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Ron,
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The audio is available from the yellow and green ground. You could connect that to an ampli speaker and confirm. If that is working then replace the amp U1. Raj At 07-03-18, you wrote:
Ok, I am new to this group and have just assembled my micro bitx. I sent an earlier message to the group explaining that I have no audio. |
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Does the 2073D work as well or better than the TDA2822? thanks, Paul K0ZYV From: N8DAH <Dherron@...> To: [email protected] Sent: Wednesday, March 7, 2018 9:45 AM Subject: Re: [BITX20] Micro BitX No Audio TDA2822? The Ubitxv3.pdf has it
If you have no sound of any kind and the U1 chip has TDA2822 WX on it then its a safe bet the chip is blown. You have a few options for drops ins such as 2073D which is what I used to replace my blown TDA2822
-- David ?N8DAH
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Ron N4RT Scroll to the bottom for the full schematic. Arv? K7HKL _._ On Wed, Mar 7, 2018 at 8:32 AM, Ron Thomas <n4rt@...> wrote:
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I assume your uBitx arrived with the bad WX TDA2822 part.?
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This part:?? should be a direct pin-for-pin replacement of the TDA2822. Mouser part number is??513-NJM2073D, costs about $1, plus another $5 for shipping . Mouser is a top line distributor, there are other vendors. JRC strikes me as a very reputable manufacturer. An alternative is this from Tayda at $0.29: ? I think we heard from somebody in the group that this worked well for them. UTC is not a company I am familiar with, and Tayda goes for the budget end of the market. I like that UTC has cooked up what looks like a complete datasheet, not just a photocopy of the ST datasheet. Many other possibilities out there, just two that look good to me. I have not tried either one. Jerry, KE7ER? On Tue, Mar 13, 2018 at 10:27 am, Sajid Rahum wrote:
Same question also, I received ubitx today and it has the same faulty ic.? 2073D - is it a straight replacement for TDA2822? |
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ae1ct1998
I WAS GIVEN A MICROBITX WITH A BLOWN UP TDA2228M CHIP, I REAPLACED IT AND NOW THE AUDIO IS VERY LOW. IS THERE ANYPLACE ELSE THAT I SHOULD BE LOOKING TO FIND OUT WHY I HAVE LOW AUDIO? ALSO THERE IS A HISS AND NO MID OR LOW RANGE JUST HIGHS, IVE USED HEADPHONES AND A SPEAKER WITH NO RESULTS. ANY HELP WOULD BE GREATLY APRECIATED.
GARY AE1CT |
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Joe Puma
开云体育Jerry has the group discussed pulling 5v from somewhere else like use the 5v that powers the Raduino? Maybe temporarily until they can get a regulator and or new WX chip??Joe KD2NFC? On Mar 15, 2018, at 5:04 PM, Sajid Rahum via Groups.Io <zs735@...> wrote:
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Could work, first time this was suggested.
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An extra wire, the Raduino regulator would get hotter. ? On Thu, Mar 15, 2018 at 03:39 pm, Joe Puma wrote: Jerry has the group discussed pulling 5v from somewhere else like use the 5v that powers the Raduino? Maybe temporarily until they can get a regulator and or new WX chip?? |
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Regarding Joe's suggestion of using the Raduino's LM7805 to power the TDA2822:
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One objection I would have is the extra wire, needs to be dealt with every time? I unplug the Raduino.? Though not a big deal. A spare LM7805 on the bottom of the main board is more convenient. A 25 ohm 1/2 watt resistor in series with the 12v Vin lead of the Raduino's LM7805? should solve the problem with extra heat.? And/or a heatsink on that LM7805. Add caps to ground on both ends of the resistor to kill any tuning clicks. I would think those caps could be fairly small, but some here report success using electrolytic caps of several hundred uF's.? I haven't bothered, no clicks. Adding that wire for a regulated 5v from the Raduino adds opportunities for Nano clock noise to get into the receiver.? Keep it short, put a 0.01uF cap at each end. Can't use the 78L05 that gives the IRF510's their gate bias, because that regulator must be shut down during receive. Jerry On Thu, Mar 15, 2018 at 04:26 pm, Jerry Gaffke wrote:
Could work, first time this was suggested.On Thu, Mar 15, 2018 at 03:39 pm, Joe Puma wrote: Jerry has the group discussed pulling 5v from somewhere else like use the 5v that powers the Raduino? Maybe temporarily until they can get a regulator and or new WX chip?? |
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One could use a voltage drop resistor. The higher the current draw, lower would be the voltage to the TDA2822 On 16 Mar 2018 4:56 am, "Jerry Gaffke via Groups.Io" <jgaffke=[email protected]> wrote: Could work, first time this was suggested. |
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Quiescent current into the TDA2822 is around 6ma, peaks can be 1 Amp.
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Though?100ma might be sufficient for moderate speaker volumes. You would need two resistors for a voltage divider, and maybe waste 500 ma through them to keep the voltage moderately well regulated. Good spot for an LM7805. On Thu, Mar 15, 2018 at 07:10 pm, Ashhar Farhan wrote:
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Some of these clones seem to blow for no particular reason.
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I think we primarily must limit the supply voltage, not so much the current under load. Though they are really good at dealing with variations in supply voltage. The series resistor in the 12v supply could be a solution for a good (non WX)?TDA2822 if you are worried about exceeding the max power dissipation spec at high volume and low load impedance. On Thu, Mar 15, 2018 at 07:22 pm, Jerry Gaffke wrote:
Quiescent current into the TDA2822 is around 6ma, peaks can be 1 Amp. |
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A series resistor also tends to act like a treble tone control. Low
frequencies with higher audio power levels tend to get attenuated more by a higher voltage drop while lower power audio high frequencies don't get attenuated as much. YMMV as far as the actual effect on the ear. tim ab0wr On Thu, 15 Mar 2018 19:22:33 -0700 "Jerry Gaffke via Groups.Io" <jgaffke@...> wrote: Quiescent current into the TDA2822 is around 6ma, peaks can be 1 Amp. |
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Hi, i have think if there come some tones to the input of TDA2822 on a frequency we could not hear, 20 KHz or perhaps a lower, with much higher power, than the normal wanted sound. That could burn the TDA2822. Perhaps a LP filter about 2.5 KHz in front of the volume control would be good. Just an idea. 73, Stig, oz8pz 2018-03-16 3:54 GMT+01:00 Jerry Gaffke via Groups.Io <jgaffke@...>: Some of these clones seem to blow for no particular reason. |
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