No, do NOT build that Mick Feuerbacher thing! That is a prime example of an amp that is incomplete and prone to problems that could lead to much dissapointment, like ruined speakers. I always recommend reading and following the details in the data sheet paying close attention to the components on the schematic listed as "optional", they are not optional, except for very specific cases where it is known for sure how the amp will be used, otherwise all of those components should be included so the amp will be stable under all conditions.
Mike
Mike
This is why we want pictures, could have avoided all the nonsense over PM.
What is the DC reading on the output?
so are u saying if i feed input directly from headphone jack to pin 10, it wont work and i have to attach 1k series with 20k parallel to gnd for reference?
(...bcoz lately, i ve skipped 1k on input+).
18.1-0-18.6v dc, when not connected to ic.
and when connected, it drops around 0.6v on both rails.
Yes, most (might as well assume all) opamp inputs (both the inverting and non-inverting) need a DC path to a low resistance node. A signal source may or may not provide that path for you, so you should include one yourself to be sure. The 1k resistor in series with the non-inverting input is usually there to limit current for reducing the turn-on and turn-off thumps and noises, so isn't really necessary for proper operation.
Mike
Sorry, should have been clearer - the OP has been on PMs with me for a month now and has stubbornly refused to every request to provide pictures and a schematic, even after me saying that it was not possible to remotely troubleshoot without a schematic.
It was once we saw the pics that things became clear to me
It wasn't possible to help him at one point without seeing this, and when I told him to open a thread, he assumed it was because I was being difficult, and even messaged me something about the tone. I chose to ignore that. I can't help those who will not help me help them :S
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I'm fairly sure your chips have internally combusted, if they are short-circuiting the supply voltage.
Please provide DC reading on output pin (speaker output, not supply voltage). You may have a voltage close to rail voltage here.
As Michael said, if you do not provide a DC 0V reference the chip uses the negative supply rail as the reference. This results in an initial offset of close to one supply rail (in your case, 18V) on the output, and when you connect a speaker the entire voltage appears on the speaker voice coil. This may or may not destroy your voice coil, but will burn a chip in the matter of half a second.
If you have not provided the Rin to ground you did not follow the schematic 'exactly', as you told me you had. It is important to follow exact components down to the last detail unless you understand clearly the implications of removing them.
Sad as it sounds, you will probably need new chips.
guys please help. I moved halfway across India to purchase two expensive lm3886 and now its not getting mute off. ....................I m literally crying now
Awwwww, hugs bro.
I can understand the pain.
I faced a similar problem earlier but it's resolved now.
If your problem is not solved yet, kindly check this link in Apex's thread.
http://www.diyaudio.com/forums/chip-amps/162099-lm3886-schematics-pcb-17.html#post3517936
All the very best.
Sorry, should have been clearer - the OP has been on PMs with me for a month now and has stubbornly refused to every request to provide pictures and a schematic, even after me saying that it was not possible to remotely troubleshoot without a schematic.
It was once we saw the pics that things became clear to me
It wasn't possible to help him at one point without seeing this, and when I told him to open a thread, he assumed it was because I was being difficult, and even messaged me something about the tone. I chose to ignore that. I can't help those who will not help me help them :S
sorry sir! Lack of verbal communication may have been responsible for projecting me in a bad way.
I admit that today and even that day i meant no offence to you.
Well, a month ago, i purchased another ic from nagpur and made similar connections as in datasheet, only omitting the potentiometer. And VOLA... its worked fine.
The only logical conclusion we can reach is that the shop you mentioned in calcutta is selling duplicate/damaged ics.
BTW, sadly i m off this project due to work bt will continue 2 or 3 months later.
Thanks for all of your co-operation till now. Hopefully I will catch you later.
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