lynx express not responding to dmx signal

[sabie]

ok here is what i've done so far
replaced both com chips
replaced pic
reflowed solder joints on both com chips and pushbuttons and pic
i have all three led's
the unit test fine with test program
what started all this was a ground lightning strike

the rest of controllers that were affected had bad com chips they are all currently running fine after i replaced the com chips

i don't see and board damage

so a little help or suggestions would be appreciated

[Justtazz]

I had a similar issue where the board tested fine but the jumper for wireless fell off and wouldn't work with a DMX signal.  check that it's a long shot but might be the issue

[sabie]

wireless jumper is in place and making good connection

[RJ]

If it was lighting damage there is the possiblity you have a failed trace. If they unit passes a signal to the rest of the out of the dmx #2 output then that would tell us something. If it doesn't then this also tells us something so you could try that as a test.

RJ

[sabie]

signal passes both rj45 outputs to next controller i don't see any damaged traces

[tbone321]

What are you using to supply the DMC signal and what channel is the LE set too.

[sabie]

my dmx box  i use to test all my lights it has been set to several differant start channels but is currently set to start channel 1 as i reflashed the pic
i have also used my show computer and a usb dongle with no change but i do have the signal led on the express and it goes out when cable is disconnected

[wftxlites]

Sounds like your problem is on the output side of the RS485 chip. Possibly shorted to ground. High impedance path to ground created by the lightning. That should be visible, I would think.  My other thought is that the RE enable pin on that chip may have a problem.  I think that would prevent the chip from outputting to the PIC. Not sure how RJ did this on the board.  He could better speak to that.

Maybe you can post a good pictures of the board front and back.  That has helped before identify issues. It has to be good enough so that we can zoom in and look at traces.

[sabie]

here are the photos

[RJ]

pull both the rs485 chip to the right of the DMX jacks and the pic and look for pins bent, socket damage. This means Maybe when you changed them you had an issue you are not seeing as this is the most likely since you changes the chips and we assume they are ok.

RJ

[sabie]

removed both chips and checked all sockets i even swapped the chips with a working unit no change i'm thinking about swapping out the sockets what your thought

[tbone321]

Before you go through the trouble of pulling the sockets, just check them with a continuity tester or ohm meter. 

[sabie]

ok folks
here is the latest ohm'ed out the rs485 sockets no issues
le will pass signal out of both rs485 ports
i swapped the pic with a working unit no change
i swapped the rs485's from a working unit no change
are there any discreet components between the pic and the rs485 i need to check
or can someone provide me a schematic of the circuit from the rs485 to pic so i can troubleshoot further
ALSO I CHECKED THE WIRELESS JUMPER IT IS OK
CLEANED ALL SOLDER CONNECTIONS ON RS485'S AND PIC DON'T SEE AND SOLDERING ISSUES OR TRACE ISSUES
PS I REALLY NEED SOME HELP WITH THIS ONE

[Hauvega]

Check for continuity from pin 17 on the pic to pin 5 on 485 chip.  Make sure none of the pushbutton switches are stuck on.  This can cause all kinds of problems.

[sabie]

5.3 meg
i understand the pin 17 on pic but the st485bn chip isn't pin 5 gnd?

would it be pin 1 of st485bn to pin 17 of pic if so i have a dead short
i checked all switches they seem free and not stuck