Hi Andy,
Welcome to the forums!
Since your power supply seems sized appropriately, this strikes me as likely to be a data propagation problem, especially because of the very long serial run you’re attempting. Many controllers support no more than 510 or 170 pixels per output to keep frame rates high and avoid these problems.
I’m going to list some interventions roughly in the order of “easiest to try”:
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Verify a solid 10-12V at all points along your LED path with a voltmeter while running it at high intensity. If not, either the supply is damaged; a power connection is missing, the wire is undersized, or you have a bad terminal/connection introducing extra resistance. I’d especially measure at B2 and D2. You said each strip is powered individually which makes me wonder if you severed the positive rail that would connect A2 and B2. Some colloquial wisdom is to try to always do your power injection at the first pixel of each segment, IE A1, B2, C1, and D2. However, if you kept the positive rails connected (which is fine when using a single supply), you’re right at the edge of the number of 12V pixels you can usually sustain between power injection points (usually 500, but strip copper trace and chip quality varies).
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Reduce your output brightness in Pixelblaze settings. If it causes the signal to propagate further even though your voltage was already good from step 0, then installing some capacitors across the power rails close to the first pixel of each run may help the problem. I’ve had an install where ripple current induced onto the power rails (perhaps from PWM synchronization) caused a well-powered system to flicker.
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See if you get longer signal propagation by connecting the Pixelblaze directly next to the first pixel in your run. Distance to first pixel is a notorious signal degrader. If this fixes your issue completely but you still need to have your Pixelblaze 10 ft away, your options are to:
- Try a twisted pair cable for data/ground (using one pair of an Ethernet cable will work)
- Use differential RS485 transceivers on each end of that first 10 ft
- Try changing the series resistance before the 10ft gap. You may need to add or reduce the resistance. There’s already 100 ohms in series, so adding another external 100 ohm resistor between DAT and GND would reduce the effecting resistance to 50 ohms. Adding a 100 ohm resistor in series would make the effective resistance 200 ohms. Note that given the current scale of your problem, l don’t give changing the resistance a high likelihood of being a sufficient solution.
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Just like the distance between controller and first pixel, experiment with reducing the cable gaps between, say, A2 and B2 may give you some information that it’s a progressive RF or impedance problem.
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Use an output expander. The Pro Expander is particularly well suited for this install since it’s a 12 V system, but it’s out of stock at the moment. The normal expander can also be used. Since your install is zig-zag, you might be able to get away with a combination of tricks above but run one expander channel to A1, and a second to C1.
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Run your system off 4 Pixelblazes, one at the start of each strip, and sync them with Firestorm. Note you’ll need one of the minibuck 5V regulators for each one. Three more Pixelblazes are about the cost of a pro expander, and might be well worth the cost of your time vs. doing the other high-likelihood-of-success option, #6 below. A downside is that distributing sensor board data becomes more complex, so if you had sound-reactivity in mind, you’ll need ZRanger’s Senor Multicaster. This has my highest expectation of eliminating your problem, assuming power was already solid (for example, sufficient gauge wire was preventing voltage drop).
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Combine several techniques above - the output expander with CAT6 and differential transceiver pairs on 4 channel outputs, plus a transceiver pair between Pixelblaze and the expander’s data input. I also give this a very high expectation of solving the problem, but it’s a lot of wiring that might be annoying for you.