jaytee

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About jaytee

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    MIDIbox Tweaker

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  1. How do I debug the core?

    Are you building a MIDIbox SID? You should be using an PIC18F4685. Beyond that, tough to say how to proceed, as you haven’t given us much information. If your regulator is getting very hot, that perhaps points to an error in your power circuit.
  2. Starting MB6582 build

    Unfortunately I know next to nothing about best practices when it comes to polarity protection. My own MB-6582 is polarity protected solely by virtue of its oddball 7-pin DIN connector. That said, I think either 5819 or 5817 *should* work in the given position. 5819 has a slightly higher voltage drop, but I don’t think it’s enough to stop the Vreg from working. You may also want to look over the power circuit and BOM in the sammichSID. No schematics available unfortunately, but it’s not a big or complicated circuit and there’s a good image available of the board traces, so hopefully not too hard to trace. The sammichSID, IIRC, keeps the bridge rectifier in place even though it’s not necessary for rectifying a C64 psu. This is handy because not only will it protect against reversed polarity, it’ll function normally no matter what polarity supply gets used. I’m not sure what bridge rectifier is used, but it apparently has a small enough drop that the synth functions fine on 12V.
  3. Starting MB6582 build

    Agree with Hawkeye. The different SID types make thinks a little wacky, but after setting up your ensemble it should be good. Changing the LOG flag is the most important, but I also found that adjusting the min and max filter values was a big help. Just go by ear :) Most of the circuitry in the MB-6582 is digital, so it’s pretty straightforward. If it seems to be working mostly as expected, ie changing patches, responding to input, proper LEDs lighting, then chances are that any hiccups come down to setting options in the software correctly. The synth engine is really complex, so it’s easy to miss something and get unexpected results!
  4. sammichSID: troubleshooting [SOLVED]

    Always good to hear of another sammichSID entering the world. Congrats!
  5. Starting MB6582 build

    If you’re getting 5V at JD9 then that rail isn’t sagging. Before measuring current, make sure you know how. Don’t mean to offend if you already know, but it’s very important if you don’t. If you try to measure it like current, you’ll short 5V to ground and likely fry something. (Also, make sure to change your meter *back* to voltage mode before using it again; made that mistake on my TTSH.) Anyway, I think there’s a header you can measure current from. You would have to break the circuit (take out a jumper) from the 5V regulator and the rest of the 5V rail and insert the meter in series. If I’m being totally honest, at this point I would admit defeat and install regular LEDs. The fact that your issues start as you plug in parts of the LED matrix and only get worse as you plug in more of the LEDs seems to implicate the LEDs pretty strongly. I’ll be damned if I really understand *why*, but the LEDs do seem to be the factor that differentiates your build from everyone else’s. They’re complex little devices compared to vanilla LEDs. I haven’t looked very closely at how the LED matrix on the Mb-6582 works, to be totally honest. It certainly can’t hurt to swap out the transistors if you have spares handy, but at this point I don’t particularly suspect them. Sometimes it’s better to try the easier fix before the difficult fix just in case.
  6. Starting MB6582 build

    Before you order a new regulator, run some tests, find it if your current regulator is drooping, measure current draw with and without LEDs, etc.
  7. Starting MB6582 build

    I forget exactly what I put in there, probably a 10uF. It’s probably not even necessary tbh. Otoh, I don’t think the capacitor is your problem, especially if you only put in a 10uF. Something related to current draw seems likely though, since it seems like your main deviation from a typical build are those LEDs. Did you socket your current limiting resistors? You could try pulling those and seeing if you get a consistent good boot up. If you didn’t socket them, you could cut/desolder the board connections that go with the LEDs, or if you wanted to try bigger resistors anyway, just clip them.
  8. Starting MB6582 build

    My bad, it was too big of a capacitor on the output of the sVreg, coupled with too much current draw on start-up.
  9. Starting MB6582 build

    The second video looks more or less correct. Hard to tell exactly because of the bright LEDs and otherwise dark video, but it should definitely start up with a quick light show on the matrix. IIRC, the boot-up lightshow has two stages, one with the LEDs in a more-or-less randomly flashing pattern, and one where the LEDs alternate a checkerboard pattern—I forget which comes first. You have the new Step E power circuit, right, with the sVreg? I had a little trouble with excess power draw on start-up causing issues with my boot up, but it was solved IIRC by changing to a smaller cap on the input of the sVreg. Might be a similar issue if your fancy LEDs draw too much current? It doesn’t seem like the shift registers are the problem, as least from what little I’ve seen in those videos.
  10. Starting MB6582 build

    Congrats! I remember that moment when I finally got a legible message on my screen ;) all downhill from here.
  11. Starting MB6582 build

    You may be able to get contrast working with a jumper wire from pin 15 to the contrast trimmer (and cutting a trace on the board), or it might work as-is with the ideal setting all the way to one end of the trimmer’s range instead of somewhere in the middle, but tbh if it were me, I would certainly be tempted to just get a different LCD.
  12. Starting MB6582 build

    I’m pretty sure you want to leave Pin 15 disconnected. Seems like a bad idea to be injecting negative voltages into your MIDIbox. But I’m not sure that having it connected would be enough to keep your backlight from turning on, as that seems to rely solely on proper voltage at Pin 1 and Pin 16, which you should have. So I would disconnect the LCD entirely and double check that all your voltages are still correct (ie double checking that nothing went wonky from applying -5V to pin 4 of J15). If that looks good, snip the wire attached to Pin 15 and see if anything changes. Disclaimer: We’re already a bit beyond my full understanding, so consider these comments as rough guesses rather than truth. Still, this is more or less what I would be doing to troubleshoot.
  13. Starting MB6582 build

    Okay, double-reading the data sheet and I don’t think it needs negative voltage for the backlight. But pin 15 seems to be used for something other than powering the backlight, which is odd. According to the data sheet, it supplies negative voltage as part of an external contrast adjustment circuit. The backlight seems to run on normal +5V running into A (+) and K (gnd)...but I can’t figure out where pin A is supposed to be from the pinout in the datasheet. I’m guessing the LCD itself doesn’t have any more helpful labels or anything, just pins 1 and 16 marked probably?   edit: I think the backlight power is connected internally somewhere, as opposed to needing a separate supply.
  14. Starting MB6582 build

    My issue was that the entire cable was connected backwards at the LCD end. I still got some functionality because both sides (pins 1&2 and 15&16) are power (one side for the actual LCD and one side for the backlight) so everything was in fact receiving power, but nothing else was connected correctly. I am pretty sure this isn’t your issue. Looking over your display’s data sheet (specifically the pinout), it seems like maybe your display needs a negative voltage reference for the backlight to function? This issue is described in the LCD troubleshooting document (http://www.midibox.org/dokuwiki/doku.php?id=troubleshooting_lcd_displays) but unfortunately the solution is not described there: it only gives a dead link. :/
  15. Starting MB6582 build

    Hm, I vaguely recall being confused by the pin numbering as well. In any case, the guide you linked to should be correct, as J15 has the same pinout on MB6582 as it does on a normal core (where the pins aren’t labeled, fwiw).