the_duckchild

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About the_duckchild

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    MIDIbox Newbie
  1. Starting MB6582 build

    ah, thanks - so the cap at C3? Pretty sure I only have 10uf in there already, can I go even smaller? It's just smoothing the already regulated 5V right?  Do you remember what you used, or did you mean you'd changed it to 10uf? I wonder if it can go even lower, sounds from your thread here that it isn't actually doing very much...>   thanks for the help.  I guess it might be the current draw is just too big. Although it does start up sometimes - both this and the screen misbehaving seem worse when all the LEDs are connected. I think Hawkeye is probably right about the slow cycle LEDS being retriggered too often to colour change.  So I guess I will see if I can get it to reliably start up with the colour change LEDs in before thinking about changing all the slow ones for fast ones! I guess I might try some bigger resistors and see if I can get the current draw down..
  2. Starting MB6582 build

    Will try and find the data sheet - are both sets of leds matrixed that way? I did wonder if that was why the selection leds were not changing - they are slow change so maybe get reset before they can change. Annoying, but not the end of the world I guess. The matrix ones are fast change, and they seem to be working in some ways when MIOS is running. No idea what the fancy light show is about! Kinda odd.  Going to try switching out the shift registers first I think, unless I can think of a better idea! 
  3. Starting MB6582 build

    ok, so something even weirder now..... Sometimes it doesn't boot up MIOS, but it does do a pretty thrilling light show. I assume it should not do what it is doing in video 1 in the below instagram post? When this happens (usually when it's been turned off a while, it never seems to boot. Then a quick restart or two will make it do what happens in video 2...... Is video 2 a bit closer to what is supposed to happen when you turn it on? I also seem to be getting some slightly weird LCD screen stuff going on Do you think this might be fried Shift registers from the LCD incident? I think maybe I have to try replacing them anyway.... ho hum... Still, the light show is nice!    
  4. Starting MB6582 build

    hmmm, I'm on the point of actually putting some SIDs in.... unfortunately it seems like the colour change LEDS are maybe not going to work... or at least not properly! the ones in the Matrix seem to do three colours, rather than cycle all of them.  the other LEDs are staying resolutely red.... not quite sure what's going on here. Have tried 1k/220 and a resistor leg bridge... the lower the resistance the more the matrix seems to change colour, but it's still not right. Using resistor legs seems to mess with the LCD so that it displays random characters, which doesn't sound brilliant.... bit more exploring to do I guess... shame if they are going to stay red forever!
  5. Starting MB6582 build

    big thanks for the help people, feeling a step closer for sure now!  
  6. Starting MB6582 build

    thanks Wilhelm! Much appreciated - I think I probably blew my screen as well, so am going to try ordering a replacement that doesn't require the rewiring, but if I decide I must have the white on black in the future this might come in very handy! 
  7. Starting MB6582 build

    hmm, worried about all the shift registers as well now...
  8. Starting MB6582 build

    thanks - pretty sure, I can live with a black on white screen, so am going to order one now I think. I'm sure it's possible to mod it to work, but I'm worried enough about it all working properly anyway tbh! fingers crossed I didn't fry anything except the resistor I already replaced. not sure I hold out much hope for the transistor in the contrast circuit!
  9. Starting MB6582 build

    I was wondering this. So I could in theory skip that pin, but then I think it still needs the contrast circuit.... I think another screen is going to be easier.
  10. Starting MB6582 build

    nothing more helpful than that.  that's where I was arriving as well at looking at the sheet  -  pin 15 is out from the negative voltage generator. tbh I might just order a white on black version, which appears to be the right configuration rather than try and mess around too much...... thanks for helping I would have just had suspicions about it, but you kinda confirmed what I was thinking.  
  11. Starting MB6582 build

    thanks for the help with this... I should probably just get another screen, but I did like the idea of white on black text.... it seems relatively simple to make the circuit: http://www.shellyinc.com/techDCtoDC.htm I am still a bit confused as to what pins 15 & 16 do though?  do you think it is it expecting -5V dc at 15 or 16? And what does the other one get?  the tech spec seems to show an optional "negative voltage generator" providing negative voltage from Vee, almost as if I just need to hook pin 15 to pin 16.... that can't be it though surely?
  12. Starting MB6582 build

    thanks.... and I was wondering about the negative voltage bit..... Need to decide how wedded to White on Black I am I guess and maybe get a different lcd if I can't work it out....
  13. Starting MB6582 build

    Found your thread by the way Jaytee   sounds like maybe the backlight polarity was reversed? can't tell from that really if it was just the backlight or the whole wiring though.... Stuck at work now, but going to try just powering the backlight both ways when I get home. Because it's a negative screen it might just look completely blank/dead with the backlight off, maybe it's fine.... I hope anyway <fingers crossed>
  14. Starting MB6582 build

    thanks - that suggests I've probably blown something or done some dodgy soldering I guess! If the LCD backlight should work as soon as it has power, will test just those two pins with a separate power supply first and make sure I didn't kill the screen. Then I guess triple check the screen wiring/contrast pots/transistor tbh I am pretty sure I have the wiring right at this stage, so maybe I messed up elsewhere...
  15. Starting MB6582 build

    and the datasheet for the screen:   http://www.farnell.com/datasheets/1934384.pdf?_ga=2.140056819.1137552968.1543683871-797736446.1534442896