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Chip Amps Amplifiers based on integrated circuits

LM3886T Problem, I think
LM3886T Problem, I think
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Old 28th December 2005, 01:39 AM   #1
Panelhead is offline Panelhead
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Default LM3886T Problem, I think

I recently had a failure in an using a LM3886T chip. The amp about blew up my eardrums on one channel. It was a real loud buzz.
After disconnecting it I found almost the full positive rail voltage on the output. It was disasembled to check for problems, and nothing wrong was found. Check the chip and it was not shorted on either rail.
Powered back up, and the chip acted up a little and finally stabilized. It even amplifed. Operated fine for about an hour. But then started passing dc again.
This is not how I expected a LM3886 chip to fail. I always thought they either work, or they do not. This seems intermittant.
When I have time, I will clip it out and try to install another in the circuit board. Hopefully this problem will not still be there.
Have others seen these chips act up, settle down, and start acting up again?

George
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Old 28th December 2005, 01:50 AM   #2
odysseybmx414 is offline odysseybmx414  United States
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do you have a loose solder somewhere or a connection touching something it shouldnt??
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Old 28th December 2005, 03:08 AM   #3
Jay is offline Jay  Indonesia
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indeed you should check connections in your power supply
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Old 28th December 2005, 06:16 AM   #4
peranders is offline peranders  Sweden
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LM3886T Problem, I think
Since you were using the uninsulated "T" version, was the insulation 100%?
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Old 28th December 2005, 10:07 AM   #5
Panelhead is offline Panelhead
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Default Good news

I have double checked all connections and the status of the mica insulator. But the come and go nature made me think that clipping out the LM3886T would only be a lot of work for nothing.
Guess I need to dig back into the circuit board again and see what has caused this. It acted up after playing one morning for a couple of hours. It had been sailing along for a couple months.
I was sitting about 10 feet away when the 32 vvolts hit that speaker. My ears rang for a day. My wife was downstairs and she thought something blew up. Lowther drivers are tougher than most think.

George
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Old 28th December 2005, 10:08 AM   #6
sagarverma is offline sagarverma  India
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Quote:
It even amplifed. Operated fine for about an hour. But then started passing dc again.
check all the solder joints carefully.dry joints cause probs.
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