Thanks for the reply. :)

The drivers went bad. LED's are OK. The ztx603 is rated 1 amp, but they 
say can handle several times that for brief periods. Don't know how hot, 
don't know when they blew, could have been while soldering,  just as 
going through testing, revising software, etc. with board on the table, 
no ESD protection (yea,I know that's not the greatest), but this 
typically hasn't been an issue. Humidity has been 55% or more, but even 
in the winter when it gets considerably lower, hasn't been a problem. I 
don't think heating will be a problem once installed. A TV remote 
control only transmits briefly a pulsed signal. Was more concerned with 
static electricity when someone plugs in either the RJ-45 to a wall 
mount plug, or to the 3.5mm jack in a little plastic box mounted to 
equipment or furniture.

Probably a bigger issue, is the 3.5mm plug shank is at 5 VDC which goes 
to a copper area that is nearly the whole PCB, the other side is ground. 
That leaves the socket nut exposed at 5 VDC. The driver completes the 
LED emitter circuit to ground. But that's the standard for IR emitters. 
Most I have made myself from a T-1-3/4 IR LED's, nothing high powered, 
but want the flexibility to buy off the shelf later.

William "Chops" Westfield wrote:
> On Aug 21, 2009, at 7:52 AM, Carl Denk wrote:
>
>   
>> I have 6 LED driver outputs, so far I have replaced 2, could have  
>> been accidental shorting during testing, or ESD??
>>     
>
> The drivers have burnt out, or the LEDs?
>
>
>   
>> This goes to a ZTX603 NPN Darlington Transistor... The Transistor  
>> emitter is to ground, and the transistor collector > 10 ohm  
>> resistor ... The return is to 5 VDC
>>     
>
> Close to half a watt dissipated by a TO92 would make me uncomfortable  
> (even though it's within specs) unless I was paying a lot of attention  
> to the fine print the the datasheet about copper area and lead length  
> and such.  How hot do they get?
>
> BillW
>   
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