Author Topic: lynx express not responding to dmx signal  (Read 5027 times)

Offline wftxlites

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Re: lynx express not responding to dmx signal
« Reply #15 on: January 11, 2015, »
If you have ohmed pin 1 to ground and it is a short then that is the problem.

ST486bn
pin 1 output to pic. Should be 4 to 5 meg to gnd.
Pin 2 Enable Vcc + (5vdc) I think.
Pin 5 is Gnd
Pin 6 A DMX In
Pin 7 B DMX In
Pin 8 Vcc + (5vdc)

Offline sabie

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Re: lynx express not responding to dmx signal
« Reply #16 on: January 11, 2015, »
st485bn pin1 of socket to pin 5 is 5meg ohms and change

i ohmed pin 1 of st485 to pin 17 of pic24fj32ga002  that should be a short right??????
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Offline wftxlites

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Re: lynx express not responding to dmx signal
« Reply #17 on: January 11, 2015, »
Assuming that pin 17 is in fact the input pin intended to read data stream. Pin 1 to PIC pin should be zero ohms.

Sorry, I don't have an LE in front of me to verify.

Offline TexasStingray

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Re: lynx express not responding to dmx signal
« Reply #18 on: January 11, 2015, »
Sabie,

Check continuity between the to points I have in circled in red. It should be a direct connection. If not then look at what I have circled in yellow. is this a bad point.
« Last Edit: January 11, 2015, by TexasStingray »
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Offline sabie

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Re: lynx express not responding to dmx signal
« Reply #19 on: January 11, 2015, »
checked a connections on trace all read less than 1 ohm even thru the wireless jumper to st485bn pin 4 looks like a good trace
i did discover on the chip i have 5 volts on pin 8 and 2and 3 with chip removed , when installed i loose the 2 and 3 pin 5 volts
if i jumper pin 8 to either pin i loose the 5 and 3.3 leds the second st 485 has these voltages present at pin 2 and pin3
so i swapped the st485 it has the same voltages as the first on socket i/e both chips act the same in socket closet to isp header
and both appear to work fine in the other position

chip acts the same with or without pic installed
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Offline tbone321

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Re: lynx express not responding to dmx signal
« Reply #20 on: January 11, 2015, »
You are saying that the unit functions properly during the test function.  What exactly do you mean by that?  Do you have lights hooked up to the outputs?
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Offline TexasStingray

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Re: lynx express not responding to dmx signal
« Reply #21 on: January 11, 2015, »
sabie,

Have you hooked up and lights and tested to see if they come on when you send DMX. If they do and you then it might just be your data led? have you tested the voltage across the data led?

Scitt
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Offline RJ

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Re: lynx express not responding to dmx signal
« Reply #22 on: January 12, 2015, »
This is how it works, the data comes in the on a pair of wires which should connect to pin 6 and 7 of the RS485 chip. then the 485 chip has power on pin 8 as I remember and ground on pin 5. Pin 2 and 3 are connected to each other and pin 5(grounded)  So then data comes out of the chip to the pic on pin #1. I believe it is pin #17 on the pic. So those should be connected. There is a jumper to disconnect it that allows the wireless to talk direct to the pic without the rs485 getting in the way so to speak (pulling the line). with this in mind hope this helps. As far as the data led ignore it, it is not a 100% setup as we found out some rs485 chips do not operate it correctly. now speaking of it. If the led was backwards or damage it could cause you issue so you might want to disconnect it to test.

RJ
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Offline sabie

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Re: lynx express not responding to dmx signal
« Reply #23 on: January 12, 2015, »
i'm going to do some more troubleshooting will post results tomorrow of what i'm seeing on this unit i will also be reading a working unit to see if i can determine the differences
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