Help needed in the UK with sammichSID - Resolved

MIDIbox SID
1

Hello All,

 

I have been having a few issues with my Sammich since I finished it, see posts here:

 

http://discourse.midibox.org/t/topic/18738

 

http://discourse.midibox.org/t/topic/18796

 

http://discourse.midibox.org/t/topic/18906

 

I have been over the board with a fine tooth comb, and cannot see any visible issues, the board has also been completely electronically tested and belled out, and anything that was wrong fixed, so i’m fairly sure it is not an electrical issue.

 

Also the patches play absolutely fine when triggered from the buttons on the Sammich, and you can noodle around with the settings and change values as you would expect.

 

The problem is that no matter what controller, keyboard or DAW i use, I cannot seem to perform the simplest task of pressing a key on a keyboard and have it play on the Sammich!

 

I have taken it to a few friends that have more MIDI knowledge than me, and they can’t seem to get it to do anything either, other than occasionally get it to play the odd note, or have it jump around from through the patches. (i think it might be a sysex/cc thing, but I don’t know enough about the inner workings of MIDI to be sure).

 

Basically what I would really like is if someone in the UK (or Nearby in Europe) could take a look at it and just verify that it actually works in a MIDI setup, and that notes can be triggered, and things are working as they are supposed to, and that it is infact my complete lack of MIDI knowledge at fault and not the Sammich (or if it is the Sammich, at least I know and won’t go insane, and can try to fix it.)

 

I really am at the end of my tether with this and have honestly done absolutely everything I am capable of to get it working, so if someone is able to help I am happy to pay for all shipping and any parts and time if required.

 

Please help me keep my sanity!

 

Thanks,

 

Kai.

2

Hi Kai,

 

I understand your feeling…

 

Frankly speaking I don’t know the Sammich, but I guess there is an optocoupler somewhere around the MIDI interface…

 

Are you sure it is the specified part? any chance to replace it eventually?

Checking the waveforms at the MIDI connector and the corresponding signals at the microcontroller inputs could help a lot, IMO…

If some MIDI controls are randomly executed, maybe it is a problem of signal integrity or noise…

 

Just my opinion.

 

Walter 

3

Hi Walter,

 

Thanks for the advice,

 

I have purchased and changed over the optocoupler as this was identified as a problem previously, I bought a few and have tried them all!

 

Rowan was able to get it to flash the MIOS, and apart from it having damaged SIDs at the time it worked, SIDs have now been replaced for fully working ones, so i really think the issue may be somewhere between the MIDI port and main PIC, but I simply don’t know enough to test.

I am trying to go through the troubleshooting page on the wiki at the moment, but if i’m completely honest i’ve lost heart in the project. 

 

So, If anyone one can help me, Please do!

4

At the moment I am fighting with my MB6582…

I flashed lots of PICs in the past, but the 4 guys in the MB6582 are making me crazy!

 

If the problem is HW, I would be happy to help you.

Unfortunately I am quite far from UK (Italy)…

5

Hi Kai,

 

Do you want me to have another look at it?

 

Have you still got my address?

6

Hi Rowan,

 

I do still have your details, It would be amazing if you could have another look at it for me, I would be really really grateful.

 

I can get it packaged up and posted up to you this weekend if that’s ok?

 

Goes without saying, but I am more than happy to pay for all shipping, parts and time.

 

Many Thanks,

 

Kai.

7

HI Kai,

 

No problem.

 

Just get in the post and I’ll have a look when I get a chance, just don’t expect me to be super fast as I’ve got loads on at the moment.

 

Cheers,

 

Rowan

8

Hi Kai, The sammichSID arrived today. I’ll try and have a look at it over the weekend.

9

Hi Rowan,

Thank you very much :slight_smile:

I appreciate your time and there is no rush my end for it.

You probably noticed I included all the cables I’ve been using.

Please let me know as and when if there are any parts or time costs and I will of course reimburse you :slight_smile:

10

It was the opto-coupler again…I’ve got it working fine now after replacing it.

11

Hi Rowan,

Thanks for letting me know, that is a bit weird as I bought 2 new ones and tried it with them both? One of which was in the sammich as sent, and the other I put in the box in a sealy bag. Is it possible I got duff optocouplers?

Are they are being fried somehow?

Does it work with the usb to midi cable as well?

I’m at a bit of a loss as to why that would happen again?

Thank you for having a look, and confirming that was the fault.

Any ideas why it might be going through optocouplers?

Thanks,

Kai.

12

Any ideas why it might be going through optocouplers?

Optocouplers are part of the MIDI specs - every MIDI device has to have them in the MIDI ins. And yes, they do happen to go bad. Having three bad ones in a row is somewhat unusual, though…

13

It does seem a bit odd, and possibly indicative of a problem somewhere else, maybe too much current is getting to it, it’s being spiked somehow?

 

I am wondering if a higher quality optocoupler might be in order, i’ve spent a few hours looking at datasheets etc this morning, and am wondering if the toshiba one listed below may be better than the replacements i bought?

 

I know they all pretty much do the same thing, but i’m wondering if a higher quality part might be a bit more resilient/tollerent?

 

Of course this is pure speculation, and I don’t actually know.

 

http://www.amazon.co.uk/OPTOCOUPLER-DARLINGTON-6N138-TOSHIBA-Square/dp/B008AHIHY6/ref=sr_1_1?ie=UTF8&qid=1434966817&sr=8-1&keywords=6N138

 

http://www.ebay.co.uk/itm/OPTOCOUPLER-DARLINGTON-O-P-Part-TOSHIBA-6N138-/390813577029?pt=LH_DefaultDomain_3&hash=item5afe4def45

14

I haven’t had a chance to look into this further yet but there must be something else causing the optocoupler to fail.

As I noted last time I had a look at the sammichSID, the backlight is not working correctly. The screen is very dull. Maybe there is a problem witht the backlight circuit that is causing problems with the optocoupler as the two are right next to each other on the PCB.

15

Hi Rowan,

 

That could be an issue, the guy i had look at it here said the same thing, he has taken the schematics and had look, and the only thing h has said so far is that lots of parts are very close to their tolerances based on the circuit diagram and components.

 

I really appreciate you taking the time to look at it for me Rowan, I hope that it’s repairable and nothing too major wrong with it.

 

Thanks,

 

Kai.

16

Hi

Did you repaired it?

17

@C_04,

 

Rowan has disabled the backlight on the LCD and has said that the box is now functioning correctly, so Im looking at getting a new LCD display, as that may be the issue.

I found an OLED which has identical specs and have had it confirmed by one of my friends who’s into electronics hardware, which should draw less power as well, so once I have the box back I’m gonna try that and see if it helps. 

 

Ill post back once i have the box and have replaced the display.

18

Hi

Then im asking Rowan now: What you can say about this backlight? Its shorted somewhere on LCD or maybe something wrong with sammichSID circuit? Did you tryied supply backlight directly using 5V? Did you measured it? Im really interrested:)

Ill explain it why im so interrested - once ive had similar issue and reason was that wires soldered to lcd started to separate because i often bend them and one of them make a short. Maybe it wasnt exactly one of separated wires but definitely it was something like a hair. My lcd was then dull, blinking, restarting uC etc etc etc.

I would like to know that LCD is damaged and need to be replaced or its repairable. OLEDs are not so cheap but if someone is rich then… hehehe

Anyway LCD backlight may be powered directly from 12V via resistor maybe 1,2k - i would use that in first way. If too dark then 1k. sammichSID has some resistor to change backlight current, unfortunatelly i cant say which one because i dont have any pics with layout right now.

Cheers

G

19

Hi All,

 

Just thought i should write an update to this topic.

I have had an electronics engineer look at the sammich, and i am really happy to say that it now work perfectly as far as i can tell :slight_smile:

I have it hooked up to my AN1X making all kinds of awesome sounds and sequences.

The problem turned out to be a very elusive one to track down, The guy that looked at it tested the optocouplers and they were all fine, even the ones i had that were thought to be blown.

In the end it turned out to be a trace on the PCB about 2-3mm long that simply wasn’t there to begin with, so its a possible PCB manufacture fault on my board.

The trace has been traced and to end now and a jumper cable fitted in between, and the sammich is now functioning normally! the only thing thats not so great now is my MIDI knowledge, as it was nearly 6 years ago when i started the build, and i knew a lot more and used more MIDI devices back then and even had a little home studio, but life changes and now i dont, but i guess i now have the fun of trying to learn all over again, hopefully it won’t be too hard!

Anyway, i am delighted to finally have it working after al this time, what an awesome little machine it is.

 

Thanks to everyone thats helped me out in the thread and RL trying to get this little box going. :slight_smile: