achra

Sorry to bump an ancient thread, but I thought I would report back that I did a single 6581 midibox-sid build, using a 15vdc Triad transformer, a 7812, and a LM2575. I used the LM2575 according to the appnote with a small additional filter. Looking at the output (Both loaded & unloaded) on my scope, I don't see any indications of noisy power. Also, the final result sounds great. No strange or unpleasant noises, just a rock solid midibox SID. I entered into this idea because I really was hoping to make a small midibox sid that could be powered via a single cheap walwart supply. Attached is the schematic. Please be aware that the LM2575 is only capable of 1amp of output. Also, although switching supplies are far more efficient than linear regulators, they don't work magic. You may need to heatsink, depending on load. I hope that someone gets some use out of this, I really appreciate all of the great help I've received from other people on the forums, and of course I REALLY appreciate all of the great work that has been put into making this project so great. Thanks!

Ok, issue resolved. I installed the SID TestTone application and verified that the output amplifier stage works fine. I installed the SID Interconnect application and verified that the shift registers and SID connections are all working perfect. I swapped out a few other SID chips and verified that the issue was unchanged.. I installed the midi-mon application and verified that the midibox was receiving what I thought I was sending.. Still the same behavior (very little actual synth sound, which was always the same note, and extremely loud popping at the beginning and end of each note).. I inspected the boards and connections, carefully verifying that everything looks good. At this point, I decided that it simply had to be a software issue.. and that is where I found my problem, my PIC programmer software was set to PIC18F4680 instead of PIC18F4685. I had wrongly assumed that because everything seemed to be "acting" right, then the bootloader must have been burned correctly. Wrong. Best guess, the fuses are set differently on these two microcontrollers, and I had the PIC fuse settings set to something crazy. (This is my first PIC project, up until now I've been exclusively an Atmel AVR hobbyist). So, anyways, there is my story for posterity, for the next poor idiot to get clued in with the cluebat. Thanks again for your endless patience, Nils. -Adam

Ok, I attempted to create a "simple patch" with the values you specified.. Same issue as before. Attempting to send the preset bank via MBSidv2_editor, I was not able to get the send to work at all. I can receive the bank OK, though. Would it be worth posting my patch bank & ensemble bank here so that you can look at it? Is it possible that this kind of behavior might be caused by a bad BC547?

I uploaded the patches using midi-ox with delay of 750ms after F7, as described in the preset patches readme.. But I'll try the sidv2 editor in the morning. Thanks for the values of a "simple" patch, I'll definitely try that as well. Hm. I was just thinking of following the MC34063 appnote, I have had great luck with that in the past for various projects at a total cost of under $5. I will let you know how that sounds during my next build. Thanks again for your continued help, I'll report back with my findings in about 9 hours. -Adam

Thanks for your prompt reply. Below are my answers: 1) Good to know. Any chance that my initial program/bring-up procedure was incorrect somehow? Should default bootloader/mios have been correct for my purposes? 2) Yes, MIOS Studio, in smart mode. 3) The 5v regulator was getting hot until I heatsinked it. This is expected, since I have a nice backlit LCD display on that supply. The 12v regulator is warm, but not hot. (This thing must not draw much current?) 4) Yes, the two grounds are connected, and I verified that there is 0.0v potential difference between the ground on both boards. 5) Yes, 6581's. As an aside: The next one of these that I make, I am thinking it would be better to use a 15vdc wallwart and 12vdc linear regulator for the SID.. But use a bucking switching supply for the 5vdc and avoid all of these heat problems and ugly transformers.. Unless there are good reasons for not using a switching supply on a piece of audio equipment? -Adam

Hello all, and thank you very much in advance for your help. This is my first midibox project, so please assume firstly that I have simply made some kind of user error. First, my setup: I am using a Midibox CORE & Midibox SID module from smashtv. I programmed the PIC18F4685 with the bootloader that came with MIOS 1.9g, and uploaded MIOS 1.9g via midi. All is good, the LCD display works great. I uploaded the SID test application, I get a nice clean 1khz tone. All so far so good. I erased the PIC, burned the bootloader, uploaded MIOS, and uploaded the midibox sid v2 application, and uploaded the presets patch bank. Everything looks and controls great.. However, this is my problem: When I try to play a note on my midi keyboard, the SID module makes a loud POP and then I hear a brief quiet synth noise. The synth noise I am hearing sounds like it might be the right kind of SID sound, but it is very quiet (I have this sent through a nice amplifier, but still this is very audible), and also it doesn't sustain, it just is a very brief. The upshot is that any notes I play, it just sounds like a bunch of extremely percussive loud popping noises (followed by very quiet brief synth on some of the patches).. I've tried other SID chips, they all sound the same. Any thoughts? My power supply is a pair of matched transformers, one outputting 18vac@500ma and the other outputting 9vac@1a. I'm measuring 22vdc at the rectifier before the 12volt linear regulator for the SID module, and 10vdc at the rectifier before the 5volt linear regulator for the core module. Please let me know if there is anything else I can provide to offer assistance. Thanks for this great project, I can't wait to get it working properly. -Adam

Thanks for all of your help, I appreciate it. Ok, I'll get a midi cable and see if MIOS is installed. Also, is it possible that my lcd display doesn't support 4-bit? Is it necessary for me to use 4-bit lcd display if I am only using a single core single sid setup?

Hello, thanks very much for any help that you can give me on this issue. I've never built a midibox before, and my hope is to complete a Midibox Sid when all this is done. I should go ahead and mention that I am by no means new to electronics or soldering, I came here by way of designing nixie clocks compulsively for years.. I bought the Core module kit from SmashTV, and assembled it. Everything looks great. I had the PIC18F4685 set to the following ID: 0000 0000 0000 0000. Is this correct? I wired up the power supply, and I'm measuring regulated 5v everywhere I should.. But on my 2x20 LCD, I only get a single row of blocks.. No letters at all. They adjust with the contrast pot, though. I wired it in "4-bit mode", because I read that this is the appropriate way to hook up a PIC18F4685 based project LCD. D0, D1, D2, D3 are not connected to the LCD display, and D3 is pulled high via 1k resistor. Thoughts? What have I done wrong?