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MB-6582 issues (LED, encoder, patch freeze)


ChinMuzik
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I just completed the construction for the CS of my MB-6582 build. I succesfully installed MIOS and the LCD is working as it should.

After installing the current limiting resistors...when powering on the unit..I get a strange pattern on the matrix. Column 6 of the matrix flashes steady and no matter what I do it won't stop. Also, a couple of the controls LED's pulse very dimly in the same pattern as the matrix column. Several buttons do not work.

There is also no response from any of the encoders. And another strange thing, the LCD will freeze and time a "poly" patch is selected. 

20161022_065137.jpg

 

EDIT: I noticed the LCD freezes only when browsing patches while the matrix is in MATRIX mode...if in METER mode it browses fine.

I checked soldering and no bridges and no visible shorts. I reaseated the shift registers and checked 5v supply on all sockets which is good. Cleaned all residue on the bottom of the board. 

 

After reseating, now some buttons behave strangely (along with ones that didn't work before)

Edited by ChinMuzik
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Hi,

May be you need to recheck the soldering again, not for bridges only.  The Led's and buttons are controlled by shift registers. To check all the ic's  for right direction installed, for no broken ic pins and for it are in the sockets in right places.

Regards,

Janis

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I've checked all shift registers and swapped them with new ones. Checked orientation twice. 

Reflowed each socket and checked continuity on each socket pin. ibthen checked continuity on each pin on the cables connecting the base and CS which was fine.

Also, the resistor networks have proper orientation...however I did not populate this board sobI do not know if these are the type that have common pin 1. How would I discern? 

I'm still getting nothing from the encoders and some buttons do not work...SId 2 and 4 work but not SID button 1 and 3..

 

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Hi,

Here is  a default encoder assignments for MB6582:

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

On the shift registers appropriate pins you can check pulses, when you slowly turn encoders knob.

ps. some encoders have a different pinout, if yours are from another manufacturer.

"Patience is a virtue" 

Regards,

Janis

 

 

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All the diodes polarity are correct. 

The LCD no longer freezes when selecting patches. Not sure what resolved that issue.

The buttons for Filter, CC, Sync, SID 1 and SID 3 do not work. Is there a way to test tactile switches with a meter? Even though I highly doubt 5 switches would be bad.

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Hi,

as you see it's some info from Wibas mb6582 building files.

At first you can print it for the better understanding for the matrix structure, I think.

http://wiki.midibox.org/lib/exe/fetch.php?media=mb-6582:mb-6582_cs_dout_wiring.pdf

http://wiki.midibox.org/lib/exe/fetch.php?media=mb-6582:mb-6582_cs_din_wiring.pdf

When I built my MB sid custom CS, it helps a lot.

Regards,

Janis

Edited by Janis1279
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  • 2 weeks later...

Hi,

most likely, it is a connection problem, as the full 6th matrix column lights up - check out the wiring of the 6th column and trace it, Janis linked the schems above, if i interpreted it right it should go to JD8 - D6. I'd expect the other LEDs to flash with the matrix are also connected to JD8-D6, e.g. the filter LEDs. Right?

It may be the JD8-D6 wire connecting baseboard and control surface, or something on the baseboard - manually trace back JD8-D6 on the baseboard to the shift register and see if you have any shorts or bad soldering in between...
You will find the problem!

Good luck!
Peter

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  • 2 weeks later...

Hawkeye, thank you.

I'm *think* I'm making a bit of progress here. 

As far as the background noise is concerned I checked the "known issues" and TK noted.

 

Quote

Ensure that the Audio In of the MBHP_SIDmodule is connected to ground when not used.
A certain digital background noise is common on a 6581 due to a design weakness. It's much less (-90 dB) on a 6582/8580.

I assumed the audio in is the jumper for the feedback pots..so after connecting the pots..the background noise went away only if the pots were turned to 0.

With the pots set to 0 some of the patches sound thin and turning even slightly reintroduces a fair amount of the noise.

Also,  the amplitude between each patch is all over the place (some quiet, some distorted at unity gain)

Are these inherent issues with the SID and/or design?

 

 

Edited by ChinMuzik
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I don't have feedback pots installed, so I can't comment on those. On my sammichSID, the external-ins are tied to ground by default (via switching jack) and there's very little noise.

As for the volume levels of patches, I can't really say either way without hearing an example....but it's certainly possible to set up patches to have very different volume levels...

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