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ST4 display glitching/dead? And a question on troubleshooting

Hi, so, I finally got all my parts soldered together and in testing the various parts, the display board was glitchy. Per the instructions on the final assembly I tried pressing down on the pin headers, and that sorta helped a little bit, but the glitchiness came back. Removing it, then more pressing down, then reattaching it led to a display that just plain won't come up at all now. I'm afraid that maybe I damaged it. Is there anything else I can try to bring it back to life? And, if none of that works, what part is it so I can order a replacement?

Also in my troubleshooting I have come across an issue where there's constant noise coming from the oscillators and when the display WAS working it was showing activity as if input was being triggered. I assume that when no MIDI/etc are coming in, the thing shouldn't be producing any sound, so I probably have a short or a floating pin or something somewhere. Any idea where I should start looking?

(And, now I wish I'd just paid extra to have my kit preassembled. Holy moly has this been an arduous build...)

Comments

  • Oh, I think I found the board: https://www.sainsmart.com/products/3-2-tft-lcd-touch-screen-with-sd-slot

    Did you really use a touch screen display module and just eschew the touch functionality? Weird.
  • Yup, that's the one. Resistive touch (with a stylus) is far from ideal we think. Not big touch screen fans here. Although for some purposes they are the best choice.
  • Constant noise sounds like vca's are opened when they should be closed. Check individual outputs 1,2,3,4 separately.
  • The screen seems to have come back to life overnight, but it's still glitchy at startup and the actual screen updates are very, very slow now. Any ideas? I think maybe this unit was just defective.
  • It could be.. I recall we did test them, but my memory is rusty. It's been 1.5 years. Was the display bag opened in your ST4 kit?

    There was always an issue with the first time you used a screen. After a power cycle it would work or .. in 10% of the cases.. fail. The idea was we tested before hand and threw away the broken ones.
  • edited August 22
    I'll ask my colleague (who compiled the kits) UPDATE: yes, he confirms the check was made.
  • edited August 22
    On a hunch I just tried reflowing the solder on the display connector on the EXP board and that seems to have helped. It's still slow to actually build the screen at startup but at least it's working. How fast is the initial screen buildup expected to happen? It could just be that the protocol it uses is ridiculously slow.

    It does seem like the display connector on the EXP board has a lot of wiggle room and maybe some of the contacts within that are bad. I guess I can try replacing that as well.
  • There should be an animation at 50/60 fps or so with the logo building up. That should take 2 seconds or so. After that screen buildup should be a fraction of a second. If it's slower, it's probably dealing with floating connections from the control boards.. Are they all hooked up to the exp board?
  • Ah, no, in my most recent tests it was just the exp board and display; I didn't realize the floating connections would impact everything else like that. Good to know, I'll hook everything back up again and see how well it works.
  • okay yeah with all the boards connected the screen runs just fine. It's still glitchy at startup but I can live with that. Now to figure out what's wrong with my VCAs.
  • So, the squealing noise doesn't come through on any of the individual VCA outputs or on the main left or right outs - it's ONLY on the headphone jack. So, I'm guessing the problem is with something weird happening on the mixer board itself. Guess I'll re-check all my solder joints and wiring there!
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