Problem with small on Strobes

cscool36

Full time elf
Joined
Jan 9, 2011
Messages
159
Location
Belrose NSW
Hi All,
Just wiring up my strobes. I have made a string of 15.
All are working when I was programing and programed ok.
I have one that is flashing on when triggered and flash about 3 or 4 time's then turning off and stays off.
The little chip is getting hot. I can not see any solder bridging.
I also canot reprogram the chip.


Thanks


Colin
 

AAH

I love blinky lights :)
Community project designer
Joined
Dec 27, 2010
Messages
3,446
Location
Eaglehawk
Which of the 2 chips is getting hot. I'd be hoping that it is the NUD led driver chip but as things stop working I'd say it nearly has to be the PIC. There's only a few possible culprits that I can think of.
1) There's too high a voltage being supplied to the pic. The max is 5.5V
2) The base resistor that is the connection between the pic and the transistor isn't the right value. If it's not the 1k like it should be then the pic output may be being overloaded.
3) There may be a dry joint on the pic. The connection may be intermittent and when current starts flowing due to the led firing then things may get dodgy.
4) The trigger input may be being overdriven.

Running a meter over 2 boards side by side might show up the problem. I personally would be looking at a possible short between the resistors.
 

cscool36

Full time elf
Joined
Jan 9, 2011
Messages
159
Location
Belrose NSW
Hi AAH
Thanks for the tip's.
It is the small pic chip on the back. (U2)
The voltage was at 5.35v and now is at 5.15v. Now is working but not correctly like the rest.
Thanks
Colin
 
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