[sdiy] Making toast with chips

[harrybissell]

NE5532 and 5534 are bipolar opamps that get good speed and low
noise performance with high internal bias currents. Don't worry about them.

I use a finger. If you can hold your finger firmly on the chip without
screaming
or having the part number branded into your flesh... they are not too hot.

CMOS in linear mode will be toasty-warm as well.

When your finger goes SSSssss.... when you touch... its trouble.

H^) harry

Lincoln Fong wrote:

> Can anyone tell me if Opamps should ever run hot (to the touch) and what
> it implies if they are? I notice on some audio boards I'm looking at
> that the NE5532s (and 5534s) are hot to the touch. Some hotter than
> others. None of them is under much of an output load and the supply is a
> good quality +/- 15V fed in groups through fusible 4.7 ohm resistors
> that periodically blow. Each chip has a pair of 47nF ceramic PS
> decoupling caps right by it though they're 12 years old now. Am I right
> in thinking that the ones that are hottest to touch are the most likely
> to cause excessive current draw or is it a red herring? After all the
> boards don't give trouble 95% of the time- not a very good average I
> know. The odd thing is that usually replacing the resistor cures it at
> least for a while.
>
> I notice the hotter ones generally (though not exclusively) have a P
> suffix and are dual types while the cool ones are N suffix.
>
> Finally do some of you use some kind of (infrared?) thermometer to test
> ICs for symptoms of trouble? I would get one if this were the case. What
> would be a 'dangerous' temperature?
>
> Lincoln
> _________________________
> Lincoln Fong
> http://www.fongelectronic.com