More current problems?

MIDIbox SID
1

Hello again,

As some might remember, I solved my filter problems by lowering the current sent to the LCD.

Happy to get everything working properly I then hooked up the box to renoise.

I am sending start/stop and clock from the host, as well as sending notes and CCs

My problem is that when I do all of these things together, the LCD’s brightness starts to kind of flicker and dim down…

Any idea why it would do that? If it’s just an inconvenience I don’t mind that much but I’m affraid something is wrong and I might burn out my unit …

Thanks!

Francis // XC3N

2

It sounds like you either have a short, or that your power supply is not providing enough current.

What PSU are you using?

I would double check each joint for shorts if i were you, to be certain.

3

but isn’t it weird that it only does that when it receives midi clock on top of signal?

The power supply is an universal one… set to 12v, 1a

4

but isn’t it weird that it only does that when it receives midi clock on top of signal?

The power supply is an universal one… set to 12v, 1a

Its strange alright.

1A should surely be more than enough for your MIDIbox, you shouldn’t have had to reduce the lcd brightness.

Maybe theres a short near the tracks from the midi in / optocoupler?

Does it only happen with the midi clock, or does it happen when you send MIDI CC events to it also?

Another possibility is interfernece from the clock signal.

Im stumped. :unsure:

5

I only seem to get the issue when clock is on on top of other signals… CCs or note events by themselves do not do that…

I’m not sure how to test for shorts either =s

6

I have had similar issues with LCDs on my sequencer build. This was down to the shield of the MIDI in socket being connected to ground. All was ok until I connected a MIDI cable to the PC via a midi interface, then strange things would happen. The LCDs would change brightness and sometimes flicker.

My MIDI sockets are diecast metal and fixed in a metal panel. The panel was connected to the supply ground.

The MIDI cable should only have a ground connection for MIDI outs, there should be no ground at a MIDI in. This includes the metal shield part of the plug. Most pre-made midi cables I have seen have the metal part of the plug connected to the cable shield and so will make a ground connection between the 2 pieces of equipment.

It is worth checking to see if the shield is making this ground loop.

There can be issues with switch mode power supplies where a difference in ground potential causes problems, again I had this with the sequencer. The solution was a radical piece of surgery to the power supply, I added an earth pin connection to the negative of the output. Before I added the earth connection the negative 0volt side of the power supply was at 98volts when compared to earth. This is pretty common, I have tested many SMPS and all that did not have an earth connection showed this type of potential difference between 0volts and earth.

Sorry for the long response but I hope it is of use.

Tim.

7

thank you for the long response, it was totally of use =)

you made me conscious of some mad scientist apparatus I had going in the midi out of the synth, seems fine since I disconnected that…

=s

hehehe

8

how do you guys use the java editor and control the midibox at the same time? midiyoke?