Voltge drop when plugged in

[smtodd@gmail.com]

I'm working on a model and as soon as I plug in the power injection I get a voltage drop on the line. This is without the model getting any clock signal aka "not on". should I be getting drop without the model being used? It drops from 5.3 V to around 4.1 which i thought was odd.

Then, the panels that are not on the primary string are quite a bit dimmer than the rest, which I guess is expected because they've got lower voltage to start.

Anyone have any troubleshooting recommendations?

Main Power     (bright)|   |(Dim)        Power Injected
V+ ---------------------|   |----------------------------------
Data ---------------------------------------------------------
V- ------------------------------------------------------------

[keithsw1111]

There will be a small amount of current draw per pixel even when not lit. about ~0.01A from memory as opposed to ~0.06A when fully lit. It is also possible you have a short and enough wire resistance not to pop a fuse and keep the voltage up.

[smtodd@gmail.com]

Thanks Keith~
  I have a step down converter in front and when I adjusted the voltage up a little to compensate, it would never go above 4.1 no matter how much I cranked it. As soon as I unplugged the lights it would show a 6.5v. If I take that model off and bring it into the garage and test it with a separate power supply and simple controller all is well and performs as expected.

When I take the ground wire off the power injection, the voltage remains steady, but the lights don't get any brighter. Am I correct in having the grounds tied together on the model, just not the V+?

[keithsw1111]

Grounds must be tied. Independent positives must not be tied.


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