New mini xoxbox in development

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nicdro
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Post by nicdro » Fri Aug 04, 2017 4:33 am

guest wrote:yes, those pins will short through the inductor. but, you might want to remove the inductor and make sure there is no short with it out.
yes i checked this as well. I guess i better wait for the new parts and try it again.
I removed R5 as well - is this ok?

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guest
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Post by guest » Fri Aug 04, 2017 4:44 am

yeah, removing R5 is ok.
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nicdro
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Post by nicdro » Fri Aug 04, 2017 4:47 am

I have 107k between GND and LX.
Around 8k between GND and FB.

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Luka
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Post by Luka » Fri Aug 04, 2017 8:02 am

has anyone used this board as a 2nd voice in a x0xb0x? thinking it would be pretty cool, shared controls for filter, envmod, decay, accent, but independent tune control so you can set the voices intervals apart.

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guest
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Post by guest » Fri Aug 04, 2017 11:25 pm

that would be good, but perhaps a bit difficult if you wanted all the remaining parameters to be identical. just a second, detuned VCO would probably be easier. then use the filter and VCA of the first.
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nicdro
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Post by nicdro » Sat Aug 12, 2017 4:14 am

Ok so i replaced L1 and U1 again and no changes at all.
Must be the board then. anything else i can try?

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guest
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Post by guest » Sun Aug 13, 2017 6:19 pm

you can remove all the parts from the powersupply, and measure the resistance between all pads, just to make sure that everthing that should be connected is, and everything that shouldnt be connected isnt.
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X15
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Post by X15 » Tue Sep 19, 2017 9:18 pm

I bought one of these modules here some year ago, it does not track at all really.. If i tune it to C2 then C3 will be way off, it is still in C-range but too off to not hear that it's totally out of tune.

So this is where you tune it (though i know its TM5 i should probably go for?):

Image

It really does not look like anything that would be tunable to me with a screwdriver, but i have never DIY'ed anything like this so i don't know what i'm looking at here, but it doesn't look like any trim pot i've seen on other modules. Am i out of luck?

also since you have to take it apart this board is not connected to the other, i guess i need some small cables to connect these two together if i'm gonna be able to tune it.. what are these cables called?

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Post by guest » Tue Sep 19, 2017 9:41 pm

there are some short tuning instructions here:
http://wiki.openmusiclabs.com/wiki/EuroAdapter

and more detailed ones in the manual.

the vco is tuned with TM5 and TM4. first adjust TM5 so that a note at 1V CV is half the frequency of a note at 2V CV. sometimes its easier to do this varying btween 1V and 3V and look for a 2 octave shift. either way, the important thing is that the notes are an octave (or 2) apart, and not the actual note. once you get the width set right, you can then adjust TM4 to set the pitch right for 1V CV.

the trimmers are a bit small, and a small phillips screwdriver is needed. go easy on them, as they are not meant to handle a lot of force. youll need jumper wires to get the top board off yet stay connected.
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X15
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Post by X15 » Tue Sep 19, 2017 11:00 pm

I think the middle of these trim pots looks totally round, at least in the photos i took.. but i'll give it a shot once i have located some cables. thanks!

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Post by guest » Wed Sep 20, 2017 1:50 am

so, its the outside part that moves (or trims), and that has a small + on it. the inside metal is a rounded dish, but that doesnt move. they are pretty finicky, and it takes just the right sized phillips head screwdriver. if you cant get something to catch, try a small flathead that fits well on one of the axes of the +. the trimpots are sort of bad, and i dont think id use them again.
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X15
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Post by X15 » Wed Sep 20, 2017 1:54 am

Ok then i understand, to me those "+"-things looked like they were completely locked in place.

Thanks again!

Selstrom
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Post by Selstrom » Wed Nov 01, 2017 7:55 pm

Completed the crowd supply kit this evening.

Turned on and no sound what so ever :-(

Have been over and checked all soldering etc. Made sure all jumpers are in the correct position, cleaned board etc etc. But no joy, just seems dead.

Thought it was going to be pretty straight forward as all the SMT is already competed for me.

Any tips on what I should check now?

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Post by guest » Wed Nov 01, 2017 9:02 pm

how are you testing it? it needs a CV and a gate to make sound.

debug:

1. check powersupplies. J4 pin1 = 5.3V, pin3 = 12V
2. check VCO - apply a CV and check for square wave at J6 pin3
3. check VCF - check for signal at VCF OUT.

if the VCO doesnt work, apply an external signal to VCF IN, and check if the VCF OUT has signal.
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Selstrom
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Post by Selstrom » Thu Nov 02, 2017 5:41 am

guest wrote:how are you testing it? it needs a CV and a gate to make sound.

debug:

1. check powersupplies. J4 pin1 = 5.3V, pin3 = 12V
2. check VCO - apply a CV and check for square wave at J6 pin3
3. check VCF - check for signal at VCF OUT.

if the VCO doesnt work, apply an external signal to VCF IN, and check if the VCF OUT has signal.
Thanks for the reply.

Yeah, I've tried cv and gate from a stepper acid and also from beatstep pro and hear nothing.

Also tried 2 separate signals to VCF in, and nothing.

Thinking it must be a power issue. Will check the pins now as you suggest.

Thanks again

Selstrom
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Post by Selstrom » Thu Nov 02, 2017 9:20 am

Success!

Followed steps 1 and 2 and everything fine. Which I was surprised at as thought it was s power issue.

Then checked for signal on VCF out and nothing. Resoldered the outputs and it is working thank you. Must be down to my poor soldering skills.

Sounds awesome, just need to tune it now.

Thanks again.

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Post by guest » Thu Nov 02, 2017 11:28 am

glad to hear its working
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teambanzai
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Post by teambanzai » Fri Mar 23, 2018 2:25 am

Just got done building and calibrating the kit. Had no issues calibrating using a trimmer tool. Sounds really damn good! I set the VCF to be a bit more squelchy and this little module screams.

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jgoney
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I done goofed...

Post by jgoney » Tue Sep 18, 2018 5:26 pm

Let's say hypothetically that you had built one of these (x0x-heart + pacemaker), and everything was working fine. Then, you rigged it up to calibrate it (as per the docs), but your brain stopped working and you plugged the power supply in backwards. :-( C12 on Pacemaker exploded and now you're really sad. After cleaning things up, and replacing C12 and U1 (the TL072), everything seems to work aside from the VCA output. What might be the culprit?

There's nothing coming through on J7. U1 is amplifying noise if I had to guess; pin 7 is outputting ~212mV. On the x0x-heart side, I'm able to trace a signal (the VCF output I guess) until R121, but then I get lost after that. I'm out of my league with regards to debugging that transistor network.

Any advice on how I can debug this to get it working again? It sounded awesome before I blew it up. :-(

EDIT: I subbed in a 47uF cap for C12 because I was out of 100uF. That shouldn't make a difference, should it? I mean, it's just a filtering cap, right?

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Post by guest » Wed Sep 19, 2018 9:20 am

first off, id like to apologize for that. for some reason i didnt design any reverse voltage protection into the pacemaker board, and i have no idea why, either. so perhaps tossing a few high current shottkey diodes, reverse biased, from the power rails to ground would be a good safety measure for the future. then just your powersupply fuses go, rather than the pcb.

first off, are all of the powersupply rails solid? check both the pacemaker and the x0xheart, as they have seperate supplies.

second, is there a strong signal coming out of the VCF out jack? does the filter sweep work as it should? is it triggered by incoming gates, do accent and slide work? does the tune, cutoff, envmod, and resonance work as they should? does the CV change the pitch? both saw and square work?

if all of that is good, then check for signal on the volume pot, pin1. if there is signal here, then its the mixer stage. if there isnt signal here, then its either the VCA or envelope generator. turn on accents, and set accent and decay to maximum, and then listen at the VCA output. is there any signal? if not, then its probably the VCA core, and i can walk you through that. are you good with SMT rework? those transistors are tiny.
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jgoney
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Post by jgoney » Wed Sep 19, 2018 10:59 am

guest wrote:first off, id like to apologize for that. for some reason i didnt design any reverse voltage protection into the pacemaker board, and i have no idea why, either. so perhaps tossing a few high current shottkey diodes, reverse biased, from the power rails to ground would be a good safety measure for the future. then just your powersupply fuses go, rather than the pcb.
No problem, dude :-) It's my own carelessness at fault, and I'm guessing I'll be more careful in the future. Thank you for the huge amount of time you've put into this project, especially with regards to "tech support". I, for one, certainly don't take it for granted. :tu:
guest wrote: first off, are all of the powersupply rails solid? check both the pacemaker and the x0xheart, as they have seperate supplies.

second, is there a strong signal coming out of the VCF out jack? does the filter sweep work as it should? is it triggered by incoming gates, do accent and slide work? does the tune, cutoff, envmod, and resonance work as they should? does the CV change the pitch? both saw and square work?
Everything seems to work fine aside from the VCA output (and maybe glide, but I'm not sure if that even worked before "the incident").
guest wrote: if all of that is good, then check for signal on the volume pot, pin1. if there is signal here, then its the mixer stage. if there isnt signal here, then its either the VCA or envelope generator. turn on accents, and set accent and decay to maximum, and then listen at the VCA output. is there any signal? if not, then its probably the VCA core, and i can walk you through that. are you good with SMT rework? those transistors are tiny.
Volume pot, pin 1 has no signal normally, but does receive the pulse when I turn on accents. And there's VCA output when accents are on! And the volume pot properly attenuates it! So there's progress. What would you recommend I check next? What kinds of readings/signals should I see on J7 and J9? J9 pin 1 reads a constant 5.333v (accent on and off both). J9 pin 3 outputs the signal I hear at VCA out as long as accent is on. Otherwise there's no signal.

Here's a scope screencap. Yellow is J7, pin 1, and blue is VCF out.
Image

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jgoney
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Post by jgoney » Wed Sep 19, 2018 11:08 am

One other thing I noticed: when listening at VCF out and feeding gates into accent on, the VCF output turns off when there's an accent. That's with accent->VCA turned up and accent->VCF turned down. It's like when accent is on, the envelope decay pot is ignored. I don't guess that behavior is normal.

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Post by guest » Wed Sep 19, 2018 6:05 pm

yes, accent sets the decay to minimum.

good news: the problem is in the envelope section, not the VCA. might be easier to fix. the envelope and accent run in parallel, but feed the same node. check for a gate out signal on J10, pin3 of the x0xheart. this should replicate the gate in. if you have it there, look for it again on either side of D35 on the x0xheart. if thats good, look for a short (2ms) pulse on J10, pin1. if thats good, look for it again on either side of D36 on the x0xheart.
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jgoney
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A winner is you!

Post by jgoney » Thu Sep 20, 2018 2:52 pm

Success!

I changed out Q11 and now it works! Hopefully this time I can get it calibrated without almost losing a finger :-)

Thanks again for your help! :-)

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Post by guest » Thu Sep 20, 2018 5:51 pm

wow, congrats on that. and my kudos for desoldering and resoldering that speck of dust! im suprised q11 went, its pretty well protected with that input diode.
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