Hi fellows,
As a kind person I was happy to build a Class D amp for a relative, including a modest DAC so he can switch from RCAs to USB.
First was the linear supply and a massive 500VA toroidal transformer, cheap speaker relays for avoiding pops from the Connexelectronics TA3020v3b amp.
Nice sounding, but he brought it back to me as no more DAC seen by his computer. Ok, let's see, supply ok... plug the computer back in... no problem at all in my home.
He took back his amp and then can't stand the humming transformer. Here I've gone building a DC trap for mains, still humming. Ok now a request for a SMPS. Some more work for me, but done.
Then took it back to me, again: now and then the amp shuts down. I've changed the amp board from my own stuff, so it started to cost me more than just time.
He played it for less than one week, heard a loud noise in speakers (if they ever burn I'll have to sell an organ ), and here it is back.
The amp has a blown fuse and when changed it it blows after been used as light bulb and making the supply squeals like a pig.
I still have a steady +/-50V supply, the DAC and its supply, but the amp seems to be the problem, but seems only, still a doubt about faulty supply friying amps. Or bad layout picking HF and all these guys oscillating or voodoo or ghosts...
So what you guys advise me to do? Sending the amps back to China from France will cost me more than the amp, not an option.
What can I measure on the supply to tell it's healthy?
Wich reliable amp, with high input impedance for the potentiometer and around +/-45 to +/-55V supply, should I buy?
Is cheap DIY and good sounding amplifiers come at the price of lowest quality?
And here is how I'm rewarded for building to others... My own UCD400 build ( not that cheap I must say ) is still rolling years after first power-up !
Never again for someone else, never again!
As a kind person I was happy to build a Class D amp for a relative, including a modest DAC so he can switch from RCAs to USB.
First was the linear supply and a massive 500VA toroidal transformer, cheap speaker relays for avoiding pops from the Connexelectronics TA3020v3b amp.
Nice sounding, but he brought it back to me as no more DAC seen by his computer. Ok, let's see, supply ok... plug the computer back in... no problem at all in my home.
He took back his amp and then can't stand the humming transformer. Here I've gone building a DC trap for mains, still humming. Ok now a request for a SMPS. Some more work for me, but done.
Then took it back to me, again: now and then the amp shuts down. I've changed the amp board from my own stuff, so it started to cost me more than just time.
He played it for less than one week, heard a loud noise in speakers (if they ever burn I'll have to sell an organ ), and here it is back.
The amp has a blown fuse and when changed it it blows after been used as light bulb and making the supply squeals like a pig.
I still have a steady +/-50V supply, the DAC and its supply, but the amp seems to be the problem, but seems only, still a doubt about faulty supply friying amps. Or bad layout picking HF and all these guys oscillating or voodoo or ghosts...
So what you guys advise me to do? Sending the amps back to China from France will cost me more than the amp, not an option.
What can I measure on the supply to tell it's healthy?
Wich reliable amp, with high input impedance for the potentiometer and around +/-45 to +/-55V supply, should I buy?
Is cheap DIY and good sounding amplifiers come at the price of lowest quality?
And here is how I'm rewarded for building to others... My own UCD400 build ( not that cheap I must say ) is still rolling years after first power-up !
Never again for someone else, never again!
Attachments
Symptoms sound like an output MOSFET has failed in short circuit failure mode. Amp chip is toast. Alternatively could be DC +/- wires to amp board are backwards (forward biases all of the schottkey diodes) but I wouldn't expect the wiring to be bad now if it was good before.
Building tech for relatives is a thankless job. Build a computer? It will come back in 1 week loaded with viruses. Fix/change desktop software? You've "broken Yahoo". Buy/build/repair/tune car for them? No oil change until engine dies. Etc.
The truth indeed 🙁
But for that first and last DIMyself (DIY will be my answer now!) I will finish the job. What about that board, seems a Connex one, fast plug'n play, and if buy where I live, in France, I will have a 2 years warranty:
IRS2092 Stereo Class D Amplifier 2x 200W 4 ohms - Audiophonics
But for that first and last DIMyself (DIY will be my answer now!) I will finish the job. What about that board, seems a Connex one, fast plug'n play, and if buy where I live, in France, I will have a 2 years warranty:
IRS2092 Stereo Class D Amplifier 2x 200W 4 ohms - Audiophonics
In my link they feature the datasheet wich stands use of 50 to 100k pot at the end of page 6 and at the end of page 2 that they have a kind of input stage like a preamp, should be ok?!
A pair of UCD180 with buffer is way too pricey for me now.
A pair of UCD180 with buffer is way too pricey for me now.
The Connexelectronic 500 smps is sold as being able to go down to 45v, but in fact 48.5 only, when the linked board is 47v max and said to mute over that max voltage... Iceberg ahead!
Hey, at least the person didn't threaten to sue you...
http://www.diyaudio.com/forums/lounge/179366-no-good-deed-goes-unpunished.html
I'm very hesitant to help anyone with anything after that incident.
http://www.diyaudio.com/forums/lounge/179366-no-good-deed-goes-unpunished.html
I'm very hesitant to help anyone with anything after that incident.
Terrible!
In my case I feel trapped as it's a close relative, this is a fact they have no responsability in the amp failures and the fact that the ones used are not reliable or I was just unlucky...
Part 2: ghost in the shell
Hello,
I have played a bit with the amp. The sources used are two sound cards wich have common ground at RCAs. And the amp has the same common ground at input, two loops with each side ground wired, loops that I've cut.
But that changed nothing:
First I'have scavenged another amp board and wanted to avoid noise pickup and other oscillations, done case earthing and made a steel sheet to sheild the amp: worst! Loud 50Hz hum and maybe higher frequency Out of audio band.
Ok undone all the sheilding, almost no hum, almost.
So I made wiring clean' twisted and as short as possible. Closed the lid. The case is full aluminum but the top mesh wich is of steel, so in the last unearthed case it is quite silent.
Here come the ghost: after a while, say few minutes, I touched the top steel mesh: a very loud bang in the speakers, no more sound, the Raspberry crashed and amp silent.
Rebooted all, but plugged in my CDP to check if the amp was still alive and let the suspicious Rapsberry away. Mistake! Touched the top steel mesh (not wiried to anything remeber, just physically closing the top of the amp!) and again a loud bang in speakers and everything crashed even the CDP!
Case and top steel mesh earthed: hum pickup, left unwired: silent... Until you touch the steel and crash everything.
What is that crazy ussue? Should I make a plastic top or alu? Why these bangs and noise pickup? The mesh being a terrific antenna and capacitor?
Any idea welcome!
Hello,
I have played a bit with the amp. The sources used are two sound cards wich have common ground at RCAs. And the amp has the same common ground at input, two loops with each side ground wired, loops that I've cut.
But that changed nothing:
First I'have scavenged another amp board and wanted to avoid noise pickup and other oscillations, done case earthing and made a steel sheet to sheild the amp: worst! Loud 50Hz hum and maybe higher frequency Out of audio band.
Ok undone all the sheilding, almost no hum, almost.
So I made wiring clean' twisted and as short as possible. Closed the lid. The case is full aluminum but the top mesh wich is of steel, so in the last unearthed case it is quite silent.
Here come the ghost: after a while, say few minutes, I touched the top steel mesh: a very loud bang in the speakers, no more sound, the Raspberry crashed and amp silent.
Rebooted all, but plugged in my CDP to check if the amp was still alive and let the suspicious Rapsberry away. Mistake! Touched the top steel mesh (not wiried to anything remeber, just physically closing the top of the amp!) and again a loud bang in speakers and everything crashed even the CDP!
Case and top steel mesh earthed: hum pickup, left unwired: silent... Until you touch the steel and crash everything.
What is that crazy ussue? Should I make a plastic top or alu? Why these bangs and noise pickup? The mesh being a terrific antenna and capacitor?
Any idea welcome!
Attachments
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In fact with no lid, just touching the front selector switch (again metal but not wired to anything!) it went off, a faint "tick" can be heard and the PS makes a high pitched noise then. I am just touching a isolated part outside of the amp! Black magic, curse?
Makes me crazy!
Makes me crazy!
I might be wrong but in your picture I can't find a common ground point in your amp. It might be a problem of potential difference between the DAC and the amp.
Edit: The PE (protection earth) has to be mounted directly on the enclosure, not on the PS board.
Edit: The PE (protection earth) has to be mounted directly on the enclosure, not on the PS board.
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I'll wait for some ideas before messing with it again but now it's less funny.
I can't figure anything any more but I find AC voltages everywhere between unconnected links (maybe that's a useless measurement, isn't it?), 50VAC between the RPi cable sheild and amp signal-psu ground, between my CDP and amp, between CDP and RPi, and ended up with a scary (kids here!) 100VAC between the Raspberry USB sheild and earth. No way for anyone here to touch the Raspberry and any earthed appliance. Btw, I've checked between earth and my charging iPhone: 66VAC...
How one can trouble shot that "touch your nose and fry your amp" issue when 50Hz is every where?
Have mercy, heeeeeeeelp!
Edit for ICG:
Thanks for helping! I may draw something to explain how it is wired. As for ground, the +/-50V ground is connected to the supply input on the amp board, this ground on the amp board is common to both speakers "-" and se input grounds' wich are comming directly from the RACs and the Second DAC wich is also commmon to the USB sheild. All connected to the amp board wich then serve as ground point. As for earting the Psu requires it, so I've wired it to earth directly. When I aslo wired the chassis to it (star style) it was picking noise... 🙁
I can't figure anything any more but I find AC voltages everywhere between unconnected links (maybe that's a useless measurement, isn't it?), 50VAC between the RPi cable sheild and amp signal-psu ground, between my CDP and amp, between CDP and RPi, and ended up with a scary (kids here!) 100VAC between the Raspberry USB sheild and earth. No way for anyone here to touch the Raspberry and any earthed appliance. Btw, I've checked between earth and my charging iPhone: 66VAC...
How one can trouble shot that "touch your nose and fry your amp" issue when 50Hz is every where?
Have mercy, heeeeeeeelp!
Edit for ICG:
Thanks for helping! I may draw something to explain how it is wired. As for ground, the +/-50V ground is connected to the supply input on the amp board, this ground on the amp board is common to both speakers "-" and se input grounds' wich are comming directly from the RACs and the Second DAC wich is also commmon to the USB sheild. All connected to the amp board wich then serve as ground point. As for earting the Psu requires it, so I've wired it to earth directly. When I aslo wired the chassis to it (star style) it was picking noise... 🙁
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Well, there you have your potential difference. That's exactly the point. Once you get somehow even a fraction of that into the input of the amp, you'll get a huge power 'explosion' as a result - which blows your amp.
Edit: NP, I really like to help - unfortunately at the moment I can't explain in detail how to fix it, I'm pretty down and don't have the energy to do it. 🙁 I try to help you further a bit later, maybe tomorrow. 🙁
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Hey,
that is just an amp and stuff, you and your health is worth million of amps, take care, my tiny problems will wait 😉
I'll return tomorrow with the drawing of current wiring.
As a father I'm used to say "time to get some sleep" 😉 Many thanks!
that is just an amp and stuff, you and your health is worth million of amps, take care, my tiny problems will wait 😉
I'll return tomorrow with the drawing of current wiring.
As a father I'm used to say "time to get some sleep" 😉 Many thanks!
You use a SMPS which has a pretty big filter capacitor between live/neutral and EARTH.
If SMPS "EARTH" is connected to enclosure, but enclosure is not properly EARTHED all the way to the electrical socket (and to a proper protection earth, ie, big metal slug buried in the ground) then you will notice a bit of a tickle when you touch the case, as your fingers will meet live mains through the SMPS input filter caps.
If the filter caps leak or go bad, you will electrocute yourself 😀
I had a router/DSL modem "Class II" un-earthed SMPS die just like this, bad input filter cap, the metallic case went live, and it exterminated everything that was connected to it, including the phone and a few ethernet ports in various PCs... Needless to say the ethernet isolation inside also fried so the shields of every ethernet cable in the house were 230VAC. Fun, eh?
You did make a solid connection between the case and protection earth, didn't you? Yes? With mandatory washers that don't come off when you shake the case a bit and stuff?
Note that measuring voltages with a multimeter is meaningless, as it has high input impedance. Even a slight bit of capacitive coupling can cause a multimeter to read 50VAC, but if you stick a 1k resistor in parallel, then it vanishes. Measuring leakage current is a lot better. If you put your multimeter on 200mA range and probe two different metallic parts... and you read something that isn't zero mA... keep your fingers off!!!!!!!!
PS: sometimes, it is wise to cut your losses. Sucks if they're pissed, but hey, they asked for it, didn't they?
If SMPS "EARTH" is connected to enclosure, but enclosure is not properly EARTHED all the way to the electrical socket (and to a proper protection earth, ie, big metal slug buried in the ground) then you will notice a bit of a tickle when you touch the case, as your fingers will meet live mains through the SMPS input filter caps.
If the filter caps leak or go bad, you will electrocute yourself 😀
I had a router/DSL modem "Class II" un-earthed SMPS die just like this, bad input filter cap, the metallic case went live, and it exterminated everything that was connected to it, including the phone and a few ethernet ports in various PCs... Needless to say the ethernet isolation inside also fried so the shields of every ethernet cable in the house were 230VAC. Fun, eh?
You did make a solid connection between the case and protection earth, didn't you? Yes? With mandatory washers that don't come off when you shake the case a bit and stuff?
Note that measuring voltages with a multimeter is meaningless, as it has high input impedance. Even a slight bit of capacitive coupling can cause a multimeter to read 50VAC, but if you stick a 1k resistor in parallel, then it vanishes. Measuring leakage current is a lot better. If you put your multimeter on 200mA range and probe two different metallic parts... and you read something that isn't zero mA... keep your fingers off!!!!!!!!
PS: sometimes, it is wise to cut your losses. Sucks if they're pissed, but hey, they asked for it, didn't they?
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I will try my best, then give up.
Well you got me there, what I've done once and undone because of loud hum, was 3 tiny but well screwed wires from:
The sheet of 0.1mm steel folded around the amp board,
The bottom aluminium plate,
The frame and the top linked.
The case itself is a frame, screwed as one metal part, then plastic borders holding isolated aluminium sides.
Maybe I should start from scratch, the case, all parts linked as one elecrtical part then earthed to socket?
Well you got me there, what I've done once and undone because of loud hum, was 3 tiny but well screwed wires from:
The sheet of 0.1mm steel folded around the amp board,
The bottom aluminium plate,
The frame and the top linked.
The case itself is a frame, screwed as one metal part, then plastic borders holding isolated aluminium sides.
Maybe I should start from scratch, the case, all parts linked as one elecrtical part then earthed to socket?
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Yeah, all the metal should have a solid connection to protection earth, for safety ! This is very important.
Aluminium anodization is an insulator, so contact between aluminium parts is not enough, screws are required.
Don't forget about the filter caps in your SMPS which stand between mains and chassis... Certain IEC filters can be used without Earth, but they need to be specially rated (usually for medical use).
Safety first, then fix your hum issues.
Aluminium anodization is an insulator, so contact between aluminium parts is not enough, screws are required.
Don't forget about the filter caps in your SMPS which stand between mains and chassis... Certain IEC filters can be used without Earth, but they need to be specially rated (usually for medical use).
Safety first, then fix your hum issues.
Ok guys,
We will all spend our lifes with better things to do. I wanted to listen to music on my system. The tests and the loud bang fried one on my tweeter. (I do not have spare speakers to test so used mine).
Have no more music and damaged speakers :'(
Guess what? Another amp, a Marantz, I was kindly asked to check and I ended up just spraying contact cleaner on pot (volume imbalance cured nicely) is back in my life: they decided to wire their computer on the amp (I have no idea what they have done) and the amp is no more working while the computer shut down at that time. Of course they claim I've messed with the amp and may fix what "I" did destroy.
You guess what about this thread and the faulty amp (wich worked very well with linear supply!!!):
The end. Money back for them and amp scavenged, parts alone do work and may be sold. The joy of loops ground and noise to someone else.
Thanks for having helped guys!
My speakers.... ='(
We will all spend our lifes with better things to do. I wanted to listen to music on my system. The tests and the loud bang fried one on my tweeter. (I do not have spare speakers to test so used mine).
Have no more music and damaged speakers :'(
Guess what? Another amp, a Marantz, I was kindly asked to check and I ended up just spraying contact cleaner on pot (volume imbalance cured nicely) is back in my life: they decided to wire their computer on the amp (I have no idea what they have done) and the amp is no more working while the computer shut down at that time. Of course they claim I've messed with the amp and may fix what "I" did destroy.
You guess what about this thread and the faulty amp (wich worked very well with linear supply!!!):
The end. Money back for them and amp scavenged, parts alone do work and may be sold. The joy of loops ground and noise to someone else.
Thanks for having helped guys!
My speakers.... ='(
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