LM3886 dead no life what so ever help?

Boscoe · 18th January 2011, 12:35 PM

Okay just installed a brand new LM3886 into one of the chipamp branded PCBs, I have a +/-30V supply in all the right places but I have no life, nothing on the output no hum no audio out it's stone cold never gets warm nothing like it's not turned on but I have measured the voltage off the board. Do I have a dead LM3886?

tangmonster · 18th January 2011, 12:40 PM

mute pin?

Boscoe · 18th January 2011, 12:46 PM

It's the chipamp boards they don't have a mute pin option.

DIY Chip Amplifier Kits, PCB's, Components and Information.

At least I thought they didn't and there's no where on the board for it.

AndrewT · 18th January 2011, 12:47 PM

post schematic and photograph.

Boscoe · 18th January 2011, 12:49 PM

The schematic is the one in the national datasheet and do you want a photograph of my PCB?

tangmonster · 18th January 2011, 12:55 PM

just power up your chip and measure voltage on pin 8.

It should measure -30V

Andy5112405 · 18th January 2011, 01:01 PM

Check and Double Check your work compared with the instructions as board has a number of options that are implemented by varying the positioning of some components.

Check amplifier wiring to external circuitry iaw instructions.

The LM3886 is quite robust but will be damaged by overheating if you are too slow when soldering it to the board. Also momentary misconnection of + & - supplies will destroy it.

Andy5112405 · 18th January 2011, 01:04 PM

It might sound daft but have you connected PSU 0V to Pwr Gnd and SPEAKER -ve to PSU 0V.

Have you connected input between Sig and Sig Gnd.

I've seen it before where, because they're not shown on the diagrams, the 0V connections have been omitted.

You may hear a slight HISS from the speaker. It'll be very quiet though.

Boscoe · 18th January 2011, 01:05 PM

Quote:

Originally Posted by Andy5112405

Check and Double Check your work compared with the instructions as board has a number of options that are implemented by varying the positioning of some components.

Check amplifier wiring to external circuitry iaw instructions.

The LM3886 is quite robust but will be damaged by overheating if you are too slow when soldering it to the board. Also momentary misconnection of + & - supplies will destroy it.

Will I have any symptoms of the supply disconnections destroying it?

Andy5112405 · 18th January 2011, 01:08 PM

If you have inadvertently misconnected + & - any electrolytics on the amp board may be damaged. The IC will certainly be fried.

There are also fake LM3886 chips out there.

18th January 2011, 12:35 PM	#1
Boscoe diyAudio Member Join Date: Feb 2010 Location: England	LM3886 dead no life what so ever help? Okay just installed a brand new LM3886 into one of the chipamp branded PCBs, I have a +/-30V supply in all the right places but I have no life, nothing on the output no hum no audio out it's stone cold never gets warm nothing like it's not turned on but I have measured the voltage off the board. Do I have a dead LM3886? __________________ I thought about it once, but then thought again.

18th January 2011, 12:46 PM	#3
Boscoe diyAudio Member Join Date: Feb 2010 Location: England	It's the chipamp boards they don't have a mute pin option. DIY Chip Amplifier Kits, PCB's, Components and Information. At least I thought they didn't and there's no where on the board for it. __________________ I thought about it once, but then thought again.

18th January 2011, 12:47 PM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	post schematic and photograph. __________________ regards Andrew T.

18th January 2011, 12:49 PM	#5
Boscoe diyAudio Member Join Date: Feb 2010 Location: England	The schematic is the one in the national datasheet and do you want a photograph of my PCB? __________________ I thought about it once, but then thought again.

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18th January 2011, 12:40 PM	#2
tangmonster diyAudio Member Join Date: Jul 2007 Location: Cape Town	mute pin?

18th January 2011, 12:55 PM	#6
tangmonster diyAudio Member Join Date: Jul 2007 Location: Cape Town	just power up your chip and measure voltage on pin 8. It should measure -30V

18th January 2011, 01:01 PM	#7
Andy5112405 Banned Join Date: Nov 2006 Location: Torpoint	Check and Double Check your work compared with the instructions as board has a number of options that are implemented by varying the positioning of some components. Check amplifier wiring to external circuitry iaw instructions. The LM3886 is quite robust but will be damaged by overheating if you are too slow when soldering it to the board. Also momentary misconnection of + & - supplies will destroy it.

18th January 2011, 01:04 PM	#8
Andy5112405 Banned Join Date: Nov 2006 Location: Torpoint	It might sound daft but have you connected PSU 0V to Pwr Gnd and SPEAKER -ve to PSU 0V. Have you connected input between Sig and Sig Gnd. I've seen it before where, because they're not shown on the diagrams, the 0V connections have been omitted. You may hear a slight HISS from the speaker. It'll be very quiet though.

18th January 2011, 01:08 PM	#10
Andy5112405 Banned Join Date: Nov 2006 Location: Torpoint	If you have inadvertently misconnected + & - any electrolytics on the amp board may be damaged. The IC will certainly be fried. There are also fake LM3886 chips out there.

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