Re: UBitx no audio! Could use some advise
Ok! So I tried what was suggested and here is what I found.? R253 was bad and ?I was able to replace but that did not fix.? I suspect a blown TDA2822M. I have one on order, so now I wait until it arrives and I swap it out. ?If there are still issues I will continue to work the problem and post if I get stuck again. Thanks Jerry!
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On Feb 28, 2018, at 10:59 AM, Jerry Gaffke via Groups.Io < jgaffke@...> wrote: Remove PA-PWR from the rig so the IRF510's won't be working, then try sending CW. Does the sidetone come through the speaker?? If not, you have a very simple? path from CW-TONE to the speaker to debug.? Perhaps wire a speaker between? the junction of R250,R251 and ground, should hear the sidetone there if it's coming? out of the Nano properly.? ? If not, triple check connections at the volume pot and out to the speaker. Many here have reported a blown TDA2822M, apparently due to shorting the speaker line to ground. Probably best to add a series resistance of 4 to 8 ohms at the output of the TDA2822M and/or reducing the supply voltage to the TDA2822M:? ? ?? /g/BITX20/message/42723If you suspect a blown TDA2822M, you could of course swap that chip out. Hard to get as NXP has discontinued manufacture, perhaps now cloned in China? An alternative is to google for "lm386 kit", and wire that into the volume control pot. Perhaps permanently. If you hear the sidetone when transmitting CW but no receiver audio, try soldering a wire across nodes M1,M2 in case the relay at K2 is not working properly.? Does that fix receiver audio? Can you hear a pop when stroking C50 with a screwdriver? Beyond that, perhaps try the tricks shown in this video on receiver debug. The wire he uses is just 3 or 4 feet of hookup wire, nothing on the other end, it is acting as an antenna to pickup up random noise. ?? Be sure to restore the hacks I suggested (PA-PWR removed and M1,M2 short) before trying to operate the rig. Jerry, KE7ER On Wed, Feb 28, 2018 at 04:20 am, Brett Deschene wrote:
Audio is completely nonexistent. No sidetone heard from CW, no static, hissing, popping, nothing.
I am pretty sure the issue is something simple and located on the board somehow but even with the schematic of the received audio path I just do not know how to diagnose and am not sure where on the board to take readings. Any help would be much appreciated.
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Re: U1 fried - Replacement
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The chip is rated to work with a 4¦¸ load so a 4¦¸ resistor should do. I doubt the chip would blow so fast that FB fuse wouldn¡¯t protect it.
Clark Martin
KK6ISP
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On Feb 28, 2018, at 4:00 PM, Jerry Gaffke via Groups.Io <jgaffke@...> 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.
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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 ?BitX. ?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).
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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.
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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
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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 ?Bitx. ?I don¡¯t intend to short it out but then almost no one does.
?
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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 ?Bitx. ?I don¡¯t intend to short it out but then almost no one does.
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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 ;)
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Don't know when I get to it.. but I will follow your lead.
I already ordered some germanium diodes to build a RF probe.
To be continued..
John
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Yes, if you can transmit CW then it has to be somewhere between Q6 and Q22,
since CW is transmittted by unbalancing the modulator immediately following Q22.
If the receiver works, then the three mixers and local oscillator are ok.
So if you still have trouble transmitting SSB, then it's Q6 or one of the bidi amps on the TX side,
and the bidi amps seldom give us trouble.
You could try unbalancing the modulator by injecting 5vdc through a series 4.7k resistor
at T7 pin 3 (and pin 5).? This is how we generated CW on the Bitx40:??
? ??
If that does transmit CW, then it has to be around Q6.
Your 10mhz scope may just barely see something in the 12mhz IF section through Q42,?
and probably nothing at all in the 45mhz IF section at Q20,21,22.
If you wind up debugging those sections, you may need to build a diode RF probe or something similar.
Jerry
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On Wed, Feb 28, 2018 at 02:50 pm, John wrote:
But as CW seemed to work the first day I thought I had to look somewhere in the modulating circuitry. Have the schematics
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can one confirm the actual dimension of the ubitx board L by W ?
Tnx
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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
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Let me second Neil's evaluation of Carl¡¯s cases. They are excellent and he is a great ham to deal with. 73 Mike KF6KXG
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I did have power on CW, at least the first day before so smoked U1 with a stereo Sony noise canceling headset.
I didn't have my straight key yet bit i just shorted a cord that i had plugged in the key jack.
Had some trouble getting the scope to sync but the signal on the collector of Q6 was much stronger than the Mic input.
Scope has 10MHz bandwidth so it should work on the lower bands.
Most likely the TDA will arrive saturday than i can start from scratch again.
Will measure the voltages as you mentioned. But as CW seemed to work the first day I thought I had to look somewhere in the modulating circuitry. Have the schematics printed but in my professional career I worked more with higher voltages.
Am not afraid to try but just need some guidance as I am fairly new to radio electronics.
John
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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.
??
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
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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 ;)
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Re: Another shipping Notification Update
ordered my Ubitx Dec. 27, 2017 Rcv'd yesterday Feb.27, 2018. had to be here and sign for it re DHL 73 WA9DOH
On Wed, Feb 28, 2018 at 7:13 AM, Daniel Conklin <danconklin2@...> wrote: I ordered mine on the 29th of December 2017, and I haven't gotten notice of shipping yet.
Dan W2DLC
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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
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On Wed, Feb 28, 2018 at 01:38 pm, Jerry Gaffke wrote:
ACE Hardware store has an amazing
collection of nuts and bolts and spacers, nylon and brass and steel, imperial and metric.
Including some nice generic knobs for electronics.?
I was just there last Saturday to get some M3 screws.? I didn't even think to look for knobs!? I'll pay more attention next time, and maybe have some coffee before I go.
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For those in the US, bereft of a 3D printer, our local ACE Hardware store has an amazing
collection of nuts and bolts and spacers, nylon and brass and steel, imperial and metric.
Including some nice generic knobs for electronics.? ?
Nylon spacers are easily cut to size with an Xacto knife.
Jerry, KE7ER
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On Wed, Feb 28, 2018 at 12:10 pm, Michael Hagen wrote:
3D printed spacers, Knobs, and Bezel.? It is like cheating to make exactly the spacer you need!? Since they are ABS, I can heat a 4-40 bolt on the stove and TAP them with treads too.?? The LCD Backlight has a bump at one end,? so to get the LCD parallel you need an inside spacer about 1/8".
?
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Fw: [BITX20] Another shipping Notification Update
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-----Original Message----- From: Richard Stanley Sent: Wednesday, February 28, 2018 4:56 PM To: [email protected]Subject: Re: [BITX20] Another shipping Notification Update My paypal still says nothing but just got a text message from DHL asking for ?27 Their website says delivery by end of business on Monday (y) Richard G7OED -----Original Message----- From: Vince Vielhaber Sent: Wednesday, February 28, 2018 4:20 PM To: [email protected]Subject: Re: [BITX20] Another shipping Notification Update Check paypal in case you just didn't get the notice. Vince. On 02/28/2018 08:13 AM, Daniel Conklin wrote: I ordered mine on the 29th of December 2017, and I haven't gotten notice
of shipping yet.
Dan W2DLC
-- Michigan VHF Corp.
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Here is my BitX..
3D printed spacers, Knobs, and Bezel.?
It is like cheating to make exactly the spacer you need!? Since
they are ABS, I can heat a 4-40 bolt on the stove and TAP them
with treads too.?? The LCD Backlight has a bump at one end,? so
to get the LCD parallel you need an inside spacer about 1/8".
Mike, WA6ISP
?
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They are metric 3 mm.? So you have to use 3mm
bolts those for the supplied spacers.
Most places have plastic spacers too.? Get 4-40
size ones.? Un-threaded 0.096" or 0.1" and you can use #4
sheet metal screws or self thread 4-40 screws.? Check
Mouser.? Or mail order surplus, like All Electronics.
Buy long ones and cut them off to the length you
need.?? The ACE and other local hardware stores have brass
and Al. tubing for model making.
K&M Metals or some name like that.? Al. ,
Brass, or Copper is easier to work with than steel.
You could cut up spacer from them too.? Could even
go to putting nuts at the other end?
Our local ACE has a whole section of hardware,
including Metric.
?
73's Mike WA6ISP
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On 2/28/2018 8:20 AM, R S via Groups.Io
wrote:
This Group is mighty nice.? I have
enjoyed it tremendously for a while now and have learned
from others here.? I have a question now.? I have installed
my xbitx in an old junked Repeater Case, no testing yet, but
I would like to have better choices with the standoffs for
the board and display.? The display is a little too far in
for my total liking.? Maybe you can see with pics.? Not
finished yet.? What are the threads per inch (maybe 4-40)
and so on?? I ordered some from Mouser but were surely not
what I wanted and expected.? Any help is surely and greatly
appreciated.
Ron
KJ4FFG
--
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID? "MotDog@..."
Mike@...
--
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID "MotDog@..."
Mike@...
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Arvo W0VRA
