oliq

MB6582 Control Surface troubleshooting

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Thanks to latigid on I now have a working MB6582 base board. I can control it through MIDI and it's outputting some great sounds and the synth engine all seems to be working great. The LCD is also fine, however having some trouble with the control surface and wondered if anyone had any more ideas for me to try.

I get LEDs on, and the pots control things on the LCD, but they don't seem to control the functions they should, and jump around the navigation when turned, with some LEDs seemingly randomly turning on and off with them. Very few of the buttons seem to work, but one or two do, again performing random functions.

I've done a very thorough check of soldering, a couple of bad joints seemed to affect the behaviour but still quite random. Reading threads on here I wondered if the shift registers were at fault. I don't have any spares, but I did try swapping some of them from the SID section of the board (in unused SID slots) to the control surface section but that made no difference. I figured this is unlikely to be the problem if swapping around doesn't make any difference - I wouldn't have damaged all of them I don't think.

Any other ideas for things I can try? 

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So thanks to Jepyang who messaged me I sorted this out, I'd installed the wrong hex file and not the MB6582 one. Thanks Jepyang!

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Almost there with this build, so close now thanks to everyone's help directly and in the many existing posts I have trawled.

The next issue I have is a few of the buttons on the control surface are not doing what they should:

  • Shift
  • Menu
  • Filter Mode

I think some of the buttons on the side of the screen also.

I went through schematics in another thread of the switch matrix and figured out it's JD8 and JD5 cables and associated areas on the main board that are associated with the switches. I've tried swapping around shift registers (I don't have spares), and also checking the solder joins around JD8 and JD5 as well as the switches themselves. No change to behaviour. The control surface to main board connections are solid. Also checked diode orientation on the CS board. All looks OK.

Could the transistors have died?

Any other pointers for troubleshooting this?

 

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Posted (edited)

it sounds like you've done a bit of this, but there is a button/encoder troubleshooting guide here in case you didn't find it already:

http://www.midibox.org/dokuwiki/doku.php?id=din_module

and a link to a MIOS program to find shift register problems...

what are the buttons doing instead of what they should?
Or just not operating?

Edited by the_duckchild
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Thank you, I hadn't spotted that guide so will work through it now.

They are activating, but seem to be selecting something to do with modulation. When I press menu a column and row of the matrix flashes and it toggles through some modulation pages. Shift also. Filter mode seems to be working now.

I thought it might be diodes or switches in the matrix section not right so have checked and re flowed all those joints too.

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I've narrowed it down to the direction buttons to the right of the screen, the menu and shift buttons and the lfo waveform select button, all of which are in a similar area of the control surface. They all seem to select a function related to the modulation matrix when I press them, although each a different one. 

Using the utility in the button troubleshooting guide I can see they are all outputting midi notes, although I found it hard to interpret this as a number of buttons across the control surface seem to output the same midi note, including some that are working fine with the mb6582 software. 

 

I tried again swapping out some of the shift registers from the SID modules on cores I'm not currently using for SIDs. That didn't change the behaviour which suggests to me the shift registers themselves are OK. 

I couldn't understand how to use the shift register tool. I get I need to test voltage across some pins but not sure which ones as I'm not knowledgeable enough to quite understand the instructions. 

Lots of checking joints, cleaning and checking for any shorts but still not getting there. So close to a fully functioning mb6582 yet so far! :)

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hmm, have to admit I am not an expert here, and the main.asm file is pretty unclear to me too, sorry!
this is a probably pretty uninformed idea, but maybe another place to reflow is Q1-Q4 as I assume these are providing the clocks for the shift registers (it's not clear that they are on the schematic but I can't see what else is) and I guess that is something that might be causing the shift register to give the wrong results of button presses?
I guess one of the transistors has to be another candidate as they're not too hard to blow.
 

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Thanks, I tried Q1-Q4 to no success. Tracing the switches I am fairly sure that it must be one of the transistors, either/both t5 and t6 as they are both in the path for those switches and more delicate than other components. I've ordered some replacements so will try them. 

Unfortunately my power supply (Option E) now seems to have failed. The 5v rail has dropped to around 1v and the switching regulator is getting really hot. I wasn't doing any reworking of the power supply section so I am a bit baffled as to what has happened with it. 12v is coming into the machine fine, and the 9v rail is OK. I'm wondering if the regulator for 5v is broken, although it's still doing something as I get some voltage out of it and it's heating up in use. Wondering if I should replace the 5v regulator, but I'm cautious about what has caused this.

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Doublecheck first to see if any two of the regulator’s three legs are short-circuited (three total continuity tests). If the other rails are good, sounds like it may be a short between 5V and gnd? If you find a short, you may or may not need to replace the regulator; some are well protected and will just start working again while others will fry. If you don’t find a short between two rails...it probably still failed for a reason so probably worth it to triple-check your work (jewler’s loupe can be had for cheap on eBay!)

 

Otoh, sometimes shit fails for no apparent reason and it’s just a bad part that needs replacing. Or sometimes you accidentally shorted something while working and didn’t realize it till later. Or some other freak occurance that borks your work but otherwise won’t happen again. So don’t stress too much if you can’t find an obvious fault. Try replacing it and if it fails again, then at least you’ve established a pattern and have a better idea what to look for. And if it works, it works.

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@jayteeThanks, really helpful, will reply on the power supply issue on the power supply thread. Sorry for confusing things with multiple threads!

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Back to my issue with menu, shift, and navigation right of the display buttons not working. Iv'e replaced shift registers, replaced all the transistors for the switches, and checked all joints in that area. Still no luck fixing the problem and I'm at a loss now what to do next.

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It's working! 2 dud LEDs in the matrix was causing the CS to misinterpret button presses. Didn't realise they were dud for ages. 

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Nice! That would have stumped me.

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