Midibox works for a while and then...

Testing/Troubleshooting
1

Hello you all!

When I boot up my core MidiOX recieves random midi in (AIN not yet connected) and the LCD says … an AIN 00/B67.

After a minute or two the midi stream stops and the LCD goes out.

The only thing I notice is that the voltage regulator on the core is VERY hot. I had to attach a small heatsink.

UPDATE

When I don’t attach the LCD everything works fine for half an hour then the midi streams stops and the 7805 on the core gets very hot. Unplug the power and plug it back in restarts the core.

2

For that random stuff: You have to pull ALL unused AINs to ground. With the jumper on the core its pretty easy to do that.

How high is your supply voltage? You should not use a supply higher than 9V for the 7805.

btw: Here is how to figure out how hot the 78.. will get:

(supply voltage - 78.. voltage) * drained current = watts which go into warmth

A normal 7805 without heatsink can dissipiate about 2 Watts, above that a heatsink is a must-have.

Hope that was helping.

3

*Pay_C: I know what you discribed… I’m just testing my core

*I seems to be a bad connection. When I touch/move the core the “Recieved an AIN” EVENT XX/XX random numbering halts. When I let the CORE go the random numbering resumes.

UPDATE:

I think when I touch the core, my body has some kind of current ??? that causes the random AIN jitter. pretty cool, i think 8)

* Is it OK to supply 12V to the 7805 with (small) heatsink??

4

Yes that random stuff is a cool testing routine… ;D

Its because your body is an antenna and getting all that 50Hz (in USA 60Hz) stuff from all that power plugs around you.

12 V is a bit high… try the following if its much to hot: Just put a 7809 in front of the power supply (nearly the same circuit as the one on the core - you just dont need all that caps and stuff - only the 7809 is enough) so you power the 7805 with 9V.

To go sure, just measure out, what current the core is draining.