signs of a dead lm3886

[Ted205]

Just wondering what peoples experiences are with dead LM3886s'.

In general terms do they output DC?
Draw to much current from the powersupply?
Are they susceptible to static damage?

[Mooly]

Could be anything symptom wise... usually a hole blown in the side

[Ted205]

so there is no way you can check to see if the chip is ok? I dont have a new lm3886 to check against.

[AndrewT]

I accidentally swapped one of the AC leads for the centre tap lead feeding the rectifier. i.e. ac-ac-ct instead of ac-ct-ac.
Killed the 3886, but did not leave any evidence of overheating and certainly not any physical damage.

[Mooly]

Originally Posted by Ted205

so there is no way you can check to see if the chip is ok? I dont have a new lm3886 to check against.

Of course... you fault find... it is just an opamp of sorts after all.

With no load connected,
Measure all supplies at the IC.
Confirm all grounds OK
Confirm the inputs are at zero volts DC (assuming it's configured in a "normal" application such as in the data sheet.
Confirm the output is at zero volt DC.
Confirm the mute pin is doing what you expect voltage wise.

If it passes all those tests measure the current draw and check against the data sheet.

Make sure the feedback network is correct.

If you do all that you will most likely find something amiss that either points to a construction error, or else a destruction error that occured and that has zapped the IC.

[pacificblue]

Originally Posted by Ted205

In general terms do they output DC?

The other way round. If you get DC at rail level on the output, when the input is 0 V, the IC is fried.

Originally Posted by Ted205

Draw to much current from the powersupply?

If a load is connected, yes. If no load is connected, maybe.

Originally Posted by Ted205

Are they susceptible to static damage?

If the voltage level is high enough, yes.

[Ted205]

thanks for the useful input guys.