MB6582 CS trouble [solved]

MIDIbox SID
1

Hi everyone,

I’ve just finished soldering a MB-6582 CS and connecting it to the base PCB. The trouble is, while the base PCB & display seem to work fine (through mios studio), almost nothing works on the control surface. No LEDs light up, and no buttons or encoders work except for the menu encoder (kind of), which can scroll randomly through the patch menu briefly before stopping. After that, subsequent turns only make one character flash.

I’m fairly confident my soldering work isn’t the problem. The only other things I can think might be the cause are that: 

  1. I initially had one of the 74HC595s round the wrong way with power on. That IC got extremely hot so I cannibalised my broken Shruthi for a replacement.
  2. Before soldering the CS, I tried to temporarily connect it to the base PCB with loose connecting wires and I may have shorted one or more of them.

Is it likely to be a fried 74 chip? What would be the logical steps for troubleshooting this? I’m aware of this post: , but I haven’t tried testing the LEDs yet.

It’s frustrating to have this problem while being so close to finishing. Any help will be much appreciated! 

2

How long are your cables between the control surface and the mainboard?

3

If it were just one fried shift register, you should still have some activity, I think. That nothing is working seems to point to a more systemic issue. Maybe something wrong with the core, or perhaps a circuitry error upstream of the shift registers that somehow fried all of them at once?

Loading the LED test firmware couldn’t hurt. Reloading the MB6582 firmware couldnt hurt. Double-check that you’ve stuffed everything.

Some pictures couldn’t hurt. Some of the display (showing the encoder behavior) and of the circuit boards too?

4

Ok, I figured it out. 

The LED issue was due to me not soldering the ‘optional’ bc547s. And I fixed the non-responsive buttons/encoder problem by replacing all the 74HC165s. Whew! 

Thanks for taking the time to respond  borfo and jaytee :slight_smile: