Channel LEDs #4 &#6 not illuminated

[Creativehues]

I'm getting a checksum: 6538. 


- John

[drlucas]

According to the wiki, that's a winning combination....so you are good there.

Being terribly new to this hobby myself what I'd try to do here is pull the pic chip, touch up all the solder points and then just reseat it again. Failing that I'd be heading to the airport to get a ticket to the Academy and spending some time in the troubleshooting lounge with the others who are much smarter than me.

No harm in trying my approach, but I don't think it will get you very far...but try

Good luck!!

 
Firmware   Checksum
Pickit2   Pickit3
Standard   64C0   6538

I'm getting a checksum: 6538. 


- John

[RJ]

Swap the opto chip 6 pin chip between a channel that is working and one that is not to see if it moved.

RJ

[sjb]

As RJ and drlucus have stated. checksum is good so swap out the chips. If #6 stays as no power then I would re-solder all of the connections on the PIC and the channels that are not working.

Steve

[Creativehues]

I retouched all the connections on the pic but no change. Should I apply more a bit if solder on each joint? Right now I'm just melting what is currently on.

If I didn't have a family reunion scheduled I would be at the academy to trouble shoot this board.


- John

[DonFL]

Take a good look and ensure the pins on the socket actually made it thru the pc board hole; I've had a couple of that style socket where the pins bend underneath the socket when inserted.
 

[RJ]

You need to be careful when working with the board with it powered up but,

The pic will have a pin running to the led, then the other leg of the led hooks to a pin on the opto 6 pin chip on the top side near the led. then one of the other top pins is hooked directly to 3.3 volts.

I am not where I can see the layout to tell you which pins as I am on my phone.

When the pic chip grounds the pin it allows the 3.3v to run through the opto turning on the led inside of the chip you can not see and then the current continues out the of the opto through the channel led to light it and to the ground the pic provides. When the channel is off the pic applies 3.3 v to the led and with 3.3v on both sides of the circuit no current flows. So check this. Stay away from the pin on the bottom side of the opto 6 pin as it has high voltage on it. Be careful.

RJ

[Creativehues]

Thanks Don and RJ!  I'm pretty sure I made sure the socket pins protruded through past the bottom of the board before I solder them. I will review those connections one more time.

I'm hesitant about dealing with high voltage on the lower side of the octos. I'd be more confident with a more exacting description or even a photo with the specific points to probe identified, circled or arrowed.

I'm willing to study more about the pin layout in order for me  to test this safely.  I'd rather not hurt myself or the board, so if anyone has a link to this info please share.  Thanks!




- John

[DonFL]

I need to test a little later to confirm, so don't take me to the bank just yet, but looks like pin 1 of the opto (rightmost pin, side closest to LEDs) is the 3.3V pin, pin 2 (next pin to the left) is the connection to the LED.

If you are hesitant to power it up and take some readings, one thing you can do is a quick continuity check. I'd verify continuity from the pic pins for LEDs 4 and 6 to one side of the LED (traces are on top of the board). Safest way if you're hesitant is to remove the pic chip, and test from the socket (i.e, top of the board), as that will also confirm you didn't bend a pin under the socket. The common point between those two channels points you back to the pic and the pic socket.

If you have continuity, chips are in correctly, LEDs are in correctly, you really then need to get some voltage readings to see what is going on.   

[Creativehues]

Okay I have continuity between each opto and their corresponding LED. I also have continuity between the LEDs and their corresponding pins on the 24 pin socket and pic chip.


- John

[DonFL]

Time to do the voltage checks as RJ described.


Sent from my DROID Pro using Tapatalk 2

[Creativehues]

Sorry guys, being a newbie to electronics,  I'm feeling  a bit obtuse about RJ's explanation. Reading it aloud it makes sense to me but I'm still unclear what to probe with the power on. So I guess I need to be spoon fed step by step directions. 

Looking for something like "with the meter set to measure 3.3 volts, touch your red probe to pin 2 on the opto and the black probe to the..."

"Then do touch the red probe to this and black probe to this.. And you should get this..."

Again thanks for patience and support! I'm hoping that by spending my time trouble shooting this board, I'll learn enough to be better suited to teach my 6 year old son electronics. I think once he sees the LE and the DMX dongle combined with my laptop running vixen - his interest in electronics (and ultimately math and science) will be  stimulated.
And if not we'll at least enjoy the holidays more with blinky flashy.


- John

[Hauvega]

Does your meter have a diode test?  If so then to see if you have a reading on the meter.  This is done with power off.  Check for continuity on the opto chip pin1 to pin1 on other opto chips. 

thanks
Eric