Alain6870 Posted March 6, 2009 Report Share Posted March 6, 2009 Hello everybody,It's my first post in this forum, I hope I did it rigth ? ??? I have recently build a MB808 with my own PCB for the voice board and PCBs from smach TV for the Midibox. (1x core, 2x DOUT, 2x AIN : Very good quality).Everything is working perfectly, except for the loop menu or the spare page. I think the problem is when all may 16 leds from the step button lit together, it makes me from time to time reset the PIC. I use only low power leds and a external 5V pover supply made around a 7805, but the current seems not to be a problem.Could somebody give me a hint or explain me were my problem could come from? I am a little bit dry!Thank you for your help. Quote Link to comment Share on other sites More sharing options...
stryd_one Posted March 7, 2009 Report Share Posted March 7, 2009 Welcome aboard alain :)Yeh you got it right. Sounds like you are saying that when all the LEDs light up it causes the box to reboot... Sounds like a BOR. if you are sure it doesn't only happen with certain leds (which could mean a short) then perhaps you need a more powerful PSU. Quote Link to comment Share on other sites More sharing options...
Gridracer Posted March 7, 2009 Report Share Posted March 7, 2009 I am not sure if it fits to your problem, but if you still have the 7805 on your core boardI guess it is recommended to supply more than 5V:http://www.midibox.org/dokuwiki/doku.php?id=parts_faq (scroll down)Can't you just try it with a "wall wart" 6-12V from some other gear? Quote Link to comment Share on other sites More sharing options...
Alain6870 Posted March 7, 2009 Author Report Share Posted March 7, 2009 Hello guys,Thank you for your support! :DIn the mean time I did some measures and could find out that I am drawing a current of 330 mA with only some leds on and it goes up to 430 mA with all the 16 leds on. This is normally no problem for the 78MCT05 I have. (And it stays really cool so what?). I measured the voltage in both cases an could see that with one led on I had a voltage of 5.03 V and with all the leds on I could measure 4.97 V. (Is this the problem I don't know?) I decided to reduce the luminance of my Display (I forgot to tell you I had one in my previous message) to get less current drawn, because most of the power is used for the LCD (about 200mA at full luminance). And now my MB808 ist in working order for more than 3 hours and I don't experience the problem any more.Question: is the LCD capable of creating a current cunsumption that generates a micro breakdown in the voltage supply of the PIC? Is the BC337 ok for driving the display or is there a more adequate transistor?Promise: I take some pictures when my TR... sorry MB808 is finished. Quote Link to comment Share on other sites More sharing options...
Gridracer Posted March 7, 2009 Report Share Posted March 7, 2009 I think you have to focus on the voltage, not the current.As you supply your core with only 5V the power controler has no "reserve" to keep 5V stable when load (current) increases. It stays cool as there is nothing to regulate for him, Inlet=outlet what itshouldn't be. See the link to the WIKI.On the other hand I can not imagine that 4.97v is already a problem but I don't know for sure.Is this what you have on the pin of the Pic? Perhaps the lag of your voltag meter is to big to show the voltage drop that makes the pic reset. Quote Link to comment Share on other sites More sharing options...
stryd_one Posted March 7, 2009 Report Share Posted March 7, 2009 I think you have to focus on the voltage, not the current.question is: do you have the regulator, recifier, etc stuffed on the core?I don't imagine you do, as feeding 5V to a regulator (which needs 8 ish) generally does not work at all. If it does, have you checked with your meter to see if it's really 5V? Quote Link to comment Share on other sites More sharing options...
Alain6870 Posted March 7, 2009 Author Report Share Posted March 7, 2009 Hello,Sorry, I'm confused I wasn't clear on my first post... :-[I have no regulator on the board, and only one regulator after the tori and the rectifier.Now I had my MB808 working all the day without a problem. It seems that the "reset default" was due to a bad calibration of the luminence of the LCD display, as I explained on my previous post ,causing, I presume, a breakdown on the pic.Thanks to everybody for your involvement. Explenations are welcome as I have only presumptions no evidences. Quote Link to comment Share on other sites More sharing options...
stryd_one Posted March 7, 2009 Report Share Posted March 7, 2009 Some displays should use an extra current limiting resistor... but if it's so close to the line that such a small adjustment as brightness could fix it, you should probably consider a more powerful PSU. Quote Link to comment Share on other sites More sharing options...
Futureman Posted March 8, 2009 Report Share Posted March 8, 2009 you should probably consider a more powerful PSU.seconded (Or was that thirded?)My sequencer crashed when I had a week powersupply and all the LED's & screen light were on.It was fixed with a beefier powersupply.RegardsMike Quote Link to comment Share on other sites More sharing options...
Alain6870 Posted March 11, 2009 Author Report Share Posted March 11, 2009 Hello everybody,As promised I send 2 pics of my MB808: The case is out of wood. Next step will be painting of the MDF surfaces. it will be maybe white then.IMG_3232.JPGIMG_3233.JPGIMG_3232.JPGIMG_3233.JPG Quote Link to comment Share on other sites More sharing options...
stryd_one Posted March 12, 2009 Report Share Posted March 12, 2009 omg, an actual functional MB808! Whee :D(sorry don't see many of those!) Quote Link to comment Share on other sites More sharing options...
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