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CMB16D Weird Problem


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I just got around to finishing my project and hooked up a new CMB16D to control a set of 12v LED’s. Problem is when I go to test it in the Hardware tool I get all the LED’s going on for the 8 channels. It does this on both banks 1-8 & 9-16. I suspected bad wiring at first but I have removed everything except the 2 lights (one for each bank) and I still get the same result with all 8 on at once. If I use the cycle option to turn on one light at a time, it powers up all 8 lights for which ever bank it is currently on. If I pick one specific channel to turn on , all 8 come on in a similar fashion, it is either all 8 on or off no matter how I want to narrow it down. Hopefull that makes sense....


I have tried the following:

Firmware v1.3 and 1.2

Different 485 converters with different cat 5 cable

Tried both 485 ports and changed the address

Power from both the unit and a tried a barrel power supply, 12v to the unit is @ 5A and the barrel PS I found does 1.3A

Does anybody have an idea on what may be wrong here? Thanks in advance for any help.

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Read the DC Controller manual carefully, especially page 14:

There are two banks of MOSFETs, bank 1 for output
channels 1 to 8, and bank 2 for output channels 9 to
16. The positive outputs of a bank are all tied
together and connected through their fuse to the
positive power input. A MOSFET is used to ground
the load connected to its channel, so positive power
is always present at the load.

Are you by chance trying to switch the positive side? Got the negative side tied together, thinking it is common and the hot side is switched?

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Thanks for pointing that out, I almost forgot about that part about the positive being full time.
Nope, each LED is separate and I am not sharing a common together though.

During testing I have all channels on and set it to cycle through them on by one. I took some voltage readings and it stays almost perfectly at a steady 12V. There is a small flicker while it moves from one channel to the next but it is barely noticeable. When it gets to the second bank, it does turn off the other 8 channels and voltage drops down to 200mV and it turns the LED’s off (this is measured from a open channel with no load). It is like I have 2 channels with 8 connections per channel.

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Have you tried a reset on the board?

What happens if you disconnect all but one LED, one channel? Will it cycle on and off as it should?

What exactly are you trying to switch? Separate discrete LEDs?

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One LED on one channel still gives the same problem. I tried a 12v incandescent bulb as well, same thing.

I am building a star and have strips of LED's. There is roughly 20 LED's per strip on a board. I also have just some simple prebuilt LED light packs that are simple two wire things kinda like a flashlight. I have tested with all three but the light packs are simple so I tend to test with those more.


Sorry, I didn't answer the question.
I want to make different parts of the star light up so each channel will have strips attached. the star will grow from a small one in the middle to a larger one, to a larger one, etc.


Attached files 292798=16162-LED Pack.jpg

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Yes I have done the reset a few times (turned both address selectors to 0 and power up). It did not correct the problem.
I did have leftover heatsinks from a kit and added those since they were lying around. Think that may be causing a problem?


Attached files 292831=16163-DC Box.jpg

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runuts wrote:

Yes I have done the reset a few times (turned both address selectors to 0 and power up). It did not correct the problem.
I did have leftover heatsinks from a kit and added those since they were lying around. Think that may be causing a problem?

thats your problem..on the DC board, the tabs on the mosfets are hot, and if you are not insulating them tabs from the heatsink, you'll see the issue you are seeing.

Remove the heat sinks and your should be good to go.
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It works, it works.........

I removed the heatsinks and cleaned off the thermal paste with some isopropyl. It works like a charm now. Here I was thinking I could use the leftover pieces for something good and it turns out they crippled me. Thank you so much, never would I have thought they were hot and would do that.
Thanks again for helping me out here. Merry Christmas everybody!

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