John E. Finster Posted July 13, 2013 Report Share Posted July 13, 2013 Hi, I´m in desperate need of assistance. I´m building a Midibox_NG with 18 ssd1306 displays and I´m in the final stages. I already assembled the frontpanel and put it in a case. At first everything was fine, but then I caused a small short between the Vss-line and SDA-line for the displays (not 100% sure about the shorted lines though). The displays began to flicker, when I used some button or encoder. I thought this had to be a ground-related problem and after a long night of searching I found the short and fixed it. So far so good. But now the displays malfunction again, but in a different manner: After I power up the box, everything is fine. I inserted a syntax that puts a small "ready" message on every display and that works. After a short while (~1 minute or so) and after I´m loading the ngc file I´m working on I notice a similar fault like the one above: First, the 9th display doesn´t seem to work anymore, same for the 16th. The other displays work at first, but after a minute, little by little, they begin to flicker and the characters shift positions on screen, when I press a button. After another night of searching I´m pretty sure, there isn´t another short an the board, but there are hundreds of soldering points and I don´t even know where to start. I also noticed that the ampere of the psu is fluctuating between 0.4 and 0.7 ampere a minute after I power up the box. That didn´t happen before I caused the initial short and everything was fine. Please, I really could need some help on this. At least some kind of plan, how I could narrow down the fault. Thanks my regards Quote Link to comment Share on other sites More sharing options...
John E. Finster Posted July 16, 2013 Author Report Share Posted July 16, 2013 Hi, I´ve just solved the problem and I´m amazed about my own stupidity. I built a small pcb extension for a 3rd and 4th midi in/out into my box, which didn´t work. I can not tell yet, why it didn´t work, but for the moment I let it go because this was not a priority for me. But I didn´t disconnect the defective pcb from the core..... That caused all the problems I had the last 3 days, the malfunctioned displays, ampere fluctuations, voltage spikes on the core, the broken sd card,... Anyway, thanks for reading this testimony of my own asininity... my regard Quote Link to comment Share on other sites More sharing options...
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