midboxSEQ v2: power problem

Testing/Troubleshooting
1

hi list,

my problem is that the midiboxSEQ v2 is completely working, but only if there is a device connected to the midi-OUT port :slight_smile:

if i disconnect the midiout, the display gets a bit darker and shows no MIOS anymore. if i reconnect the midiout port, the box reboots.

any suggestions?

thanks in advance

-chris

2

Have you already double(triple)checked the wiring of your OUT port and all the solderings around the OUT circuit?

Or have you mounted your OUT connector on a metal plate which is connected to something else?

3

yes, i checked all the wires and solderings, i think, that it already was working a few days ago. is it possible, that the PSU is defective, and isnt able to bring up all the power needed? and when i connect i to the midiout, it gets power from the pc? how do i check the Amps of the PSU ? do i have to clamp some resistor between + and - and then messure on + and -  ?

-zeh

4

No, you cant get Power over MIDI cable from the PC.

Would be interresting to watch the power supply voltage whith an oscilloscope while you plug your MIDI cable. Can you meassure the 5V from the PSU when your cable is connected? I think, this has to be a wiring/soldering problem.

5

ok, the problem is solved, but, it WAS the power supply.

strange.

if i connect the ‘maybe defective’ PSU, it only works if my PCs midi IN is connected to the midiOUT of the core.

if i connect a new PSU, it works, also if there is nothing connected to the midiOUT of the core.

i dont know why this happens, i think it gets power from the PCs powersupply, over the +5V of the midiIN from the PC, dunno if this works.

thanks a lot

-zeh

6

I was having a similar problem, my core stopped transmitting midi as soon as MIOS got uploaded.  Turned out that removing the middle to the J12 jumper immediatly solved the problem.  I as well was getting the LCD to light up slightly just by connecting midi cables.  FWIW I’m currently using a M-Audio 1010lt where the midi in/out are pigtailed off the card itself, Smash seemed to think the root of the problem may by in an incompatibility between the bench supply I’m using and the computers switching PSU.  I’m going to connect my MOTU interfaces with their own PSU’s and see if they behave any better.  Perhaps we’ve found a new caveat to the MB hardware.  Also FWIW I added ALOT of bypass caps while attempting to solve the problem, only the 2 TK mentions made any difference.