how to unmute LM3886 ?

navZ · 21st May 2013, 04:59 PM

I have got LM3886 but its not getting unmute.

Please suggest Rm value for power supply of 18-0-18 dc.

When i disconnected Rm and left the pins untouched, there was only a little sound and that too even in max. input signal (full volume), indicating it to be in a mute condition.

I have seen datasheet and tried 22k, 10k, 5k,and 1.5k, but its still mute.

The rest schematics are according to figure1 of datasheet
CHANGES: replaced 22u with 47u and omitted Cm.

Please reply soon!

Mihkus · 21st May 2013, 07:59 PM

Umm.. is your mute switched on? lol...
You added a bit over 2x sized to feedback?
You need 2x less resistance between feedback and out...

I might be wrong.

overall feedback · 21st May 2013, 08:59 PM

Quote:

Originally Posted by navZ

I have got LM3886 but its not getting unmute.

Please suggest Rm value for power supply of 18-0-18 dc.

When i disconnected Rm and left the pins untouched, there was only a little sound and that too even in max. input signal (full volume), indicating it to be in a mute condition.

I have seen datasheet and tried 22k, 10k, 5k,and 1.5k, but its still mute.

The rest schematics are according to figure1 of datasheet
CHANGES: replaced 22u with 47u and omitted Cm.

I would try with Rm 18k connected to V-. It should pass current over 0.5 mA for mute off, according to datasheet.

navZ · 22nd May 2013, 07:14 AM

guys please help. I moved halfway across India to purchase two expensive lm3886 and now its not getting mute off. I placed ammeter in series to pin8, at Rm=5k, it showed 0.99 mA and at 1.5k it showed 1.42mA. But its not working either way. Accidently, I was holding sink with my hand and touched pin8, I heard a little DB gain in comparison to little sound at mute(pin 8 left opened n untouched) I have spend so much time and money that I m literally crying now

Please help me!

Rainwulf · 22nd May 2013, 07:57 AM

Ahh, i wouldnt be crying over an amp chip. Tears are conductive...

I would redo the circuit exactly like it is in the datasheet and go from there.

navZ · 22nd May 2013, 09:52 AM

are you sure its the only option? Bcoz its now same as datasheet. What you are saying is to redo the same thing and expect diff result. I can try it but by defination its insanity to expect diff result.

Isn't there any fault you can say about?

AndrewT · 22nd May 2013, 11:25 AM

the mute pin needs current to go to "unmute".
The datasheet details the range of currents that are acceptable and shows what a reduced current will do in attenuating the output.
Yes, a reduced current works as an attenuator. It is NOT a switch between mute and unmute.

overall feedback · 22nd May 2013, 07:14 PM

Quote:

Originally Posted by navZ

guys please help. I moved halfway across India to purchase two expensive lm3886 and now its not getting mute off. I placed ammeter in series to pin8, at Rm=5k, it showed 0.99 mA and at 1.5k it showed 1.42mA. But its not working either way. Accidently, I was holding sink with my hand and touched pin8, I heard a little DB gain in comparison to little sound at mute(pin 8 left opened n untouched) I have spend so much time and money that I m literally crying now

Please help me!

I have no experience with LM3886 but looks like Rm current is too small for +-18V and 5k value. Check GND (pin 7) as well as power supply pins.

Michael Bean · 22nd May 2013, 07:54 PM

Are you connecting Rm between pin 8 and V(-) as shown in the data sheet? The chip is in mute mode with pin 8 disconnected, there needs to be at least (-).5mA flowing into pin 8 to un-mute.

Mike

tauro0221 · 22nd May 2013, 08:13 PM

Try a 3K6 resistor connected from the - volts to pin 8 of the LM3886 and see if it play music.

21st May 2013, 04:59 PM	#1
navZ diyAudio Member Join Date: Apr 2013	how to unmute LM3886 ? I have got LM3886 but its not getting unmute. Please suggest Rm value for power supply of 18-0-18 dc. When i disconnected Rm and left the pins untouched, there was only a little sound and that too even in max. input signal (full volume), indicating it to be in a mute condition. I have seen datasheet and tried 22k, 10k, 5k,and 1.5k, but its still mute. The rest schematics are according to figure1 of datasheet CHANGES: replaced 22u with 47u and omitted Cm. Please reply soon!

22nd May 2013, 11:25 AM	#7
AndrewT R.I.P. Join Date: Jul 2004 Location: Scottish Borders	the mute pin needs current to go to "unmute". The datasheet details the range of currents that are acceptable and shows what a reduced current will do in attenuating the output. Yes, a reduced current works as an attenuator. It is NOT a switch between mute and unmute. __________________ regards Andrew T.

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21st May 2013, 07:59 PM	#2
Mihkus diyAudio Member Join Date: Jul 2012	Umm.. is your mute switched on? lol... You added a bit over 2x sized to feedback? You need 2x less resistance between feedback and out... I might be wrong.

22nd May 2013, 07:14 AM	#4
navZ diyAudio Member Join Date: Apr 2013	guys please help. I moved halfway across India to purchase two expensive lm3886 and now its not getting mute off. I placed ammeter in series to pin8, at Rm=5k, it showed 0.99 mA and at 1.5k it showed 1.42mA. But its not working either way. Accidently, I was holding sink with my hand and touched pin8, I heard a little DB gain in comparison to little sound at mute(pin 8 left opened n untouched) I have spend so much time and money that I m literally crying now Please help me!

22nd May 2013, 07:57 AM	#5
Rainwulf diyAudio Member Join Date: Feb 2009	Ahh, i wouldnt be crying over an amp chip. Tears are conductive... I would redo the circuit exactly like it is in the datasheet and go from there.

22nd May 2013, 09:52 AM	#6
navZ diyAudio Member Join Date: Apr 2013	are you sure its the only option? Bcoz its now same as datasheet. What you are saying is to redo the same thing and expect diff result. I can try it but by defination its insanity to expect diff result. Isn't there any fault you can say about?

22nd May 2013, 07:54 PM	#9
Michael Bean diyAudio Member Join Date: Sep 2004 Location: Minneapolis, Minnesota, USA	Are you connecting Rm between pin 8 and V(-) as shown in the data sheet? The chip is in mute mode with pin 8 disconnected, there needs to be at least (-).5mA flowing into pin 8 to un-mute. Mike

22nd May 2013, 08:13 PM	#10
tauro0221 diyAudio Member Join Date: Nov 2008 Location: Victoria,TX	Try a 3K6 resistor connected from the - volts to pin 8 of the LM3886 and see if it play music.