Problem with the last diode of the segment of one channel

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HaVecko
 
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Problem with the last diode of the segment of one channel

Post by HaVecko »

Hello, we have a Adafruit DotStar Digital LED Strip - White 144 with BANNED controller. One channel of the controller controls approximately 900 LED diods in our case and it is made from five segments connected together. There are two power input points for 1 m of the strip. Power supply performance is enough. The problem is, that one diode, the last one at one of segments but not last at channel, doesn't work correctly. Sometimes it doesn't light and sometimes, probably because interference, it lights on full power (white colour). It switches off only when power supply is switched off. Another LEDs behind this diode work correctly.
At the picture is the same situation on two channels.
Do you have any advice for me?
Thank you
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XRAD
 
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Re: Problem with the last diode of the segment of one channe

Post by XRAD »

what happens when you code for one additional pixel? Is this pixel 0 or pixel at end of strip?

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HaVecko
 
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Re: Problem with the last diode of the segment of one channe

Post by HaVecko »

I don't know exactly what number in sequence of this channel this diode is but it isn't the last one even the first one. But it is last diode of strip on cooling segment. The channel continues behind this diode as you can se at the picture. The blue/white wire is connecting LED strips between cooling segments. LEDs before and behind this diode are OK and work correctly.

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XRAD
 
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Re: Problem with the last diode of the segment of one channe

Post by XRAD »

ok . I'm sure you already thought of these questions but here they are:

Are these the only two segments doing this on the whole project or does it repeat in other areas? I think you explained above that it is only here.

Are the left and right segments shown above supposed to have identical displays in your code?

is there a wiring issue such as loss of ground or data or power? your wiring looks neat, but.......maybe....

It is very unlikely that you have 2 bad neopixels (unless damaged or grounding on the heatsink?) at the exact same spot on two different strips so most likely a wiring issue or code issue.

Ultimately, you may have to replace the strips to see if issue continues....

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HaVecko
 
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Re: Problem with the last diode of the segment of one channe

Post by HaVecko »

As you can see at the picture, on the left strip was replaced a part of two diodes because the strip behind this part didn't work. For the short time it has been worked well, after the short run it happened - one LED went off. It happened at four or five places. It is a coincidence, it happened at both sides on two paralel placed segments. Segements have the same lenght. I tried to use the other channel of the controller - from other strip which works correctly. The situation is the same = code is correct.
"Loss of ground or data or power" - it's the same for LEDs before this LED. And...if there is some mistake, what about LEDs behind this LED? They work correctly = clock and data are OK. But it's good idea - it could be a problem with contact to heatsink.
I agree with you, I will replace the part of LEDs and will see.

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XRAD
 
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Re: Problem with the last diode of the segment of one channe

Post by XRAD »

any luck?

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HaVecko
 
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Re: Problem with the last diode of the segment of one channe

Post by HaVecko »

I'm going to repair them the next week.

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Re: Problem with the last diode of the segment of one channe

Post by HaVecko »

I finished it today. I replaced broken LEDs and made ground connectivity over all segments especially at all separated parts of one channel. It had been grounded, but it had been grounded by power source wire only. It is necesary connect ground of the end of one segment with the ground at the start of another segment of one channel (in row).
It will helps I hope

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