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Old 10th November 2006, 03:13 PM   #21
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Oscillation will not kill an Overture part (LM3886 is one) out right. Instead it will get hot and then Spike protection will come on followed by thermal shutdown. Shorting leads to different supplies will also not necessarily kill it either. If you ever attached it to a heat sink it is possible to over tighten the mounting screw and crack the die but you have to crank it pretty good. Power up with out a LM3886 in the board and check all the voltages at the pins. Then try another one.

-SL
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Old 10th November 2006, 06:00 PM   #22
Lucas_G is offline Lucas_G  Netherlands
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Quote:
Originally posted by sayang001


Desolder the chip from the pcb and put it on the scanner with it's front, it is broken anyway

Here is the picture of the frontside.
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Old 10th November 2006, 06:04 PM   #23
Lucas_G is offline Lucas_G  Netherlands
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Quote:
Originally posted by SpittinLLama
Oscillation will not kill an Overture part (LM3886 is one) out right. Instead it will get hot and then Spike protection will come on followed by thermal shutdown. Shorting leads to different supplies will also not necessarily kill it either. If you ever attached it to a heat sink it is possible to over tighten the mounting screw and crack the die but you have to crank it pretty good. Power up with out a LM3886 in the board and check all the voltages at the pins. Then try another one.

-SL
Hi Spittinlama,

I will check the voltages tomorrow and report back.

Thanks for your advice.

Regards,

Lucas
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Old 13th November 2006, 06:47 AM   #24
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Lucas_G,

Your LM3886TF is fake The one I have at home are the same as the picture below:

Click the image to open in full size.

Compare the National Logo , Text Font and casing.
Also try to remove the plastic casing and see what is undernead.
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Old 13th November 2006, 08:13 AM   #25
Lucas_G is offline Lucas_G  Netherlands
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Quote:
Originally posted by SpittinLLama
Oscillation will not kill an Overture part (LM3886 is one) out right. Instead it will get hot and then Spike protection will come on followed by thermal shutdown. Shorting leads to different supplies will also not necessarily kill it either. If you ever attached it to a heat sink it is possible to over tighten the mounting screw and crack the die but you have to crank it pretty good. Power up with out a LM3886 in the board and check all the voltages at the pins. Then try another one.

-SL

Hi Spittinlama,

Today I checked voltages on the board:

Pins from left to right:

1= +33
2= 0
3= 0
4= -33
5= +33
6= 0
7= 0
8= -33
9= 0
10= 0
11= 0

I think all voltages are right, except maybe for pin 8?

The diagram states that pin 8 is for mute....?

Any comment?

Regards,

Lucas
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Old 13th November 2006, 08:16 AM   #26
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Pin 8 should be connected to the negative supply, but via a current limiting resistor. Check your PCB.
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Old 13th November 2006, 08:16 AM   #27
Lucas_G is offline Lucas_G  Netherlands
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Quote:
Originally posted by sayang001
Lucas_G,

Your LM3886TF is fake The one I have at home are the same as the picture below:

Click the image to open in full size.

Compare the National Logo , Text Font and casing.
Also try to remove the plastic casing and see what is undernead.
Hi Sayang001,

Do you really thinks so?

I have no idea how to open this chip. The housing seems heremtically sealed...

Lucas
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Old 13th November 2006, 08:19 AM   #28
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Quote:
Originally posted by sayang001
Your LM3886TF is fake The one I have at home are the same as the picture below:
Unlikely, I can't see the market being big enough to support fakes.
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Old 13th November 2006, 08:22 AM   #29
Lucas_G is offline Lucas_G  Netherlands
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Quote:
Originally posted by pinkmouse
Pin 8 should be connected to the negative supply, but via a current limiting resistor. Check your PCB.

Hi Pinkmouse,

I just measured a resistance of 10k Ohm from pin 8 to the V- entrance. This should be OK then?

Lucas
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Old 13th November 2006, 08:23 AM   #30
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Yup, that's fine for those rails.
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