CF v8 CEx Malfunction - Channel 2 Not Lighting

Hey, guys.

I am returning to the hobby after a long hiatus, having finally worked out some of the general construction issues that were stopping me during my rebuild of my second saber. Before I get into the exact problem, I would like to preface this thread by saying that I have spent the last three days poring over the manual, forums here, at FX Sabers, and at IRA, and by just generally taking my time and gathering as much information as I can possibly lay hands (or eyes, if you like) on. I have resolved several issues already, including an unresponsive RICE port, as well as an incorrectly-wired CEx. This issue is something that has cropped up during final testing, and went undiagnosed this far because I had been using low currents to test the LED connections with the board.

THE PROBLEM: The green channel on my LZ4 RGBW is very dimly lit (not observable in blade tests; you have to look directly at the star to see it), almost as if it was set to an even lower value than the 200mA test current I had been using during bench tests. No amount of futzing with RICE or manual editing of the current to that die will alter its brightness. Red and Blue function normally, in both RICE and manual editing of the Override.txt file. The green die is wired to Channel 2 on the CEx. Blue, on Channel 3, as I said is functioning as expected.

To verify that the LED is not at fault, I successfully tested all channels with my benchtop PSU. Green is blinding, even at 200mA, which leads me to believe:

-There is incorrect wiring somewhere, endemic to the connection between either the board and the CEx, or the CEx and the LED.
-The CEx has sustained damage to one of its components (maybe I knocked loose a resistor during the install?).
-There is a short of some kind, preventing correct communication between the CF and CEx.
-One or both of the wires leading from Channel 2 are damaged. Last I checked, this was not the case, but I will check again.

I have read one article by a user who had a similar issue, which was found to be a solder spatter interfering with a resistor. I will be pulling the chassis later today and inspecting my wiring more closely. I would love for that to be the issue, but I'm very careful about soldering. If it's damage to the CEx, I can certainly pull it and send it out for repairs, but...the install is kind of cramped and that would be difficult to do. I can take focus shots of the wiring and whatnot when I pull the board.

My question is whether any of the Cram-Fu Gurus here have ever encountered something like that before, and if so, how it was resolved.

EDIT: I removed the malfunctioning board and replaced it with a spare. The wiring was identical, but the new board performs correctly. The only thing I can think of is that I damaged the CEx while installing it into the chassis. Looks like I get to send it out for repairs now.

I had something very similar to that with one of the very first CEX production boards years ago. Yes, you’ll need to send it to get repaired.

Thanks for popping in, FJK.

I seriously don't know what I did to it, but at least the problem was resolved. I'm honestly very impressed with the CF8 and CEx color mixing. Now comes the long, arduous task of futzing around with the settings until it's "mine".

Actually...I think I might know what's wrong with the CEx.

As I look at it under a magnifier, I see that there are some bridged pins on the offending channel's bottom-side components. I will assume the chips are supposed to be identical, since both channels are doing the same thing. I can try clearing the solder from the bridged pins and test out the board with my spare CF. Before I do anything, I'd like to verify that the components are not supposed to be bridged the way they are. Once my camera is done charging, I'll post up a detail shot of the offending area.

If this is a problem that can be resolved with some desoldering braid and 15 minutes of work, I'd rather do it that way.

Still...no idea how that could happen. I never soldered anything to the bottom side of the board, much less to those components. The LED +/- pads aren't even anywhere near the bridged components. Is it possible that the board arrived in this condition?

It’s possible, I would talk to Chewbacca over on FX. ;)

I will try that. Thanks for the suggestion. ^_^