New mini xoxbox in development

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Post by guest » Tue Jan 10, 2017 8:20 pm

my apologies for the very frustrating tuning it requires. i had designed the x0x-heart without intending to do the pacemaker, so when i when made the pacemaker, nothing lined up.

the fastest way to do TM3 might just be to tweak it a bit, reassemble, test, open it up, tweak again. otherwise you need to run jumpers for J6, J8, RES1, and CUTOFF.
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Post by DabiDabDab » Tue Jan 10, 2017 8:30 pm

Ok, will see how to deal with this. Another problem i have is that my decay knob suddenly stopped working. It still functions as attenuator to the decay CV in jack but it doesnt function on its own, changing the decay value of the envelope with direct pot turn. What could be wrong, can u give me some heads up on what to probe, thanx!

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Post by guest » Tue Jan 10, 2017 10:26 pm

is the decay stuck at short or long decay times? if its stuck short, it could be that accent is triggered, or that the normalisation on the decay CV jack isnt connecting to +5V like it should be. sometimes those contacts are dirty.
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Post by DabiDabDab » Sun Jan 15, 2017 11:53 pm

So yeah, it was a problem with the switching mechanism of the jack, but now i suddenly got a new problem, the filter wont close to the end at fully CCW. This is with env mod and decay also fully CCW. I havent turned the case up for a few days, but its was fully closed with the pot position being fully CCW the last time i have played with it, so that is after i have repaired the env mod jack. This is getting tiresome. Does the TM3 change the position of the cutoff range? I have tried trimming it but it just tames the filter, it doesnt fully close it with decay and env mod fully CCW, that is.

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Post by guest » Mon Jan 16, 2017 12:27 am

check the cutoff CV control input jack, and make sure its normaling properly as well. envmod shouldnt have too much effect. how open is it? TM3 will have an effect, but if its more than 50% open, then its not a TM3 issue (at least if TM3 is not fully down).
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Post by DabiDabDab » Mon Jan 30, 2017 8:40 pm

This module.. i don't know what to say. I'm building a second now, since the first one fizzled out. Regarding the last inquiry, i have recognized that filter does not close totally by design so that was fine. But consistency here in general is very hard to get by judging by my experience (i have myself to blame probably).

With this second build, my VCA output is half lower than the VCF output, what was in reverse on the first build. This is when cutoff is on 100% and reso on 0%. And if i start increasing the resonance it becomes even more pronounced. Maybe there's even something more happening, namely that resonance has more pronounced effect on the VCA output when increased, meaning it lowers the amplitude more then on the VCF out, but its pretty hard to conclude that since the VCA out put gets considerably low with rising resonance so that i cant conclude if its still in same relation as is resonance to the VCF out. Lets for the ease of things say that VCA out is consistently lower then the VCF out through out its whole range and this is not affected by other knob positions. What can I do? Everything else works ok. I have exchanged the TL072 and checked the R27 and R28 which are 1K and 103K respectively.

Thanx for your help.

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Post by guest » Mon Jan 30, 2017 11:04 pm

the VCA and VCF both recieve a mix of two signals. one of them is the filter output signal, and the other is the resonance signal. it is done this way to attempt to compensate for the change in volume as resonance is modified. its possible that this mix is messed up. The VCF out is mixed on the pacemaker via R30 and R34, so maybe check the solder joints around those parts. The VCA out is mixed on the x0x-heart via C20,21 and R212,122. im not sure how those would have gotten damaged, but it sort of sounds like that is the problem (the resonance mix is disconnected). maybe have a look at them under a magnifying glass and check that they are soldered well. you can also measure resistance from the resonance pot to C20,21. is this the same x0x-heart as before, but new pacemaker? can you try swapping them around to see if its one or the other thats the issue?
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Post by DabiDabDab » Mon Jan 30, 2017 11:52 pm

I have two pacemakers and two hearts, i have tried the heart from the first module on this pacemaker and it works exactly the same as the second heart so this leads me to conclusion that heart is not a problem or that both of them are a problem. For now I have reflowed the R30 and R34 and measured resistance between res pot and C20,21 on the heart - both are 0. No change.

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Post by guest » Tue Jan 31, 2017 9:19 am

how does the gain compare between the 2 pacemakers? with the volume knob in the middle, do the 2 VCFs give the same level, but the VCAs not, or vice versa? aslo, check R29, that sets the gain on the output. should be 2.2k.
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Post by DabiDabDab » Tue Jan 31, 2017 1:45 pm

It was the R29, thanx!!

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Post by guest » Tue Jan 31, 2017 4:55 pm

cool, glad you got it fixed. i should have mentioned that earlier, but i got confused about which resistors were which, and you mentioned you had looked at the ones around the gain section.
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Post by Schizopilz » Mon Feb 27, 2017 3:20 pm

Hi, I look to buy what it takes to do the project, in the near future.
I have a volt meter which make reading only two decimal after point.
I speak for adjusted 5.333 dcV if I adjust to 5.33 V is it correct?

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Post by guest » Mon Feb 27, 2017 5:34 pm

its ok if you only have 2 decimal places. the 5.333V isnt too critical to the sound (it being 5.33V wont change how it sounds). the 5.333V was only necessary for setting the 1V/octave in the original synth because if its DAC. the x0x-heart doesnt use a DAC, so this isnt a problem.
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Post by Schizopilz » Tue Feb 28, 2017 1:24 pm

guest Thank you for the quick reply.
I spoke too fast, I realized that I had a DCV counter on my oscilloscope.

I have a question for the pacemacer mods, even if I take the LM555 Fairchild I can make the VCF gain changes '' R26 '' and VCF Mix '' R30 ''?

I want no compromise on the exit I want it to strike. :twisted:

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Post by guest » Tue Feb 28, 2017 2:22 pm

the R26 and R30 mods can be done independent of each other or the LM555.
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switch

Post by midirobot » Fri Apr 14, 2017 1:43 pm

hello : )
do you think those switch will fit the pacemaker ?
https://www.banzaimusic.com/taiway-dpdt ... ature.html
or somebody maybe have a mouser part number because must order to them soon.

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Post by Schizopilz » Fri Apr 14, 2017 2:11 pm

It takes absolutely Multicomp 2MD6T1B5M2RE
http://www.mcmelectronics.com/product/26-2160

Mouser they do not have this piece

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switch

Post by midirobot » Fri Apr 14, 2017 2:24 pm

thanks for the quick reply !!
out of stock or super expansive everywhere i can order from France : (
will wait back in stock at farnell (or maybe somebody have 2 spares ?? )

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Post by Schizopilz » Fri Apr 14, 2017 2:29 pm

http://www.cafr.ebay.ca/itm/13195532503 ... 1436.l2649

This is really a good module! It sounds loud. When you go build do not forget to sleep the two capacitors C12, C13

midirobot
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switch

Post by midirobot » Fri Apr 14, 2017 2:52 pm

ordered,thanks !

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Post by Brueckenstein » Sat Apr 29, 2017 5:41 am

You also think the VCA output is causing too much noise?

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Post by nicdro » Sun Jun 18, 2017 3:16 am

Hi,
I had several problems getting the right voltages. The regulator on the pacemaker was getting hot and on the lm358 of the power circuit i got 35-40V which was crazy. I remounted the LM and got at least 2.5V on the 5.33V rail and 1.4V on the +12 rail. So i took off the LM again and wired +5V and +12V directly from euro. I have popped D31 and replaced it with a 4148 Diode but with a different footprint. Nevertheless all voltages are fine now (except +5.333V is +5V) but i still dont get it working. There is a really quiet 40Hz sound coming out of both the VCF and VCA output which is volume-adjustable by the RES pot. Any Ideas? I wait to reinstall a new LM in the power circuit and the right footprint of the D31 but there might be other issues on any other sections. Any idea where to look at? Where do i check the output on the heart itself to be sure it is not the pacemaker not working.
Thanks!

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Post by Altitude909 » Sun Jun 18, 2017 7:07 am

if you actually put 40V on it I'd assume you killed everything that was connected to that rail

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Post by guest » Sun Jun 18, 2017 7:30 am

its very likely the switching regulator is blown. its possible that one of the feedback resistors on the regulator isnt soldered well, and the regulator railed high. this would blow out the LM358 in the power supply section. is this a recent purchase from synthcube?

its possible that a lot of the downstream components are also fried at this point. but, you can scope it out if you want. be sure to aplly a >1V CV to the CV input. then verify that this appears at the CV out (J5 pin2). next, check for VCO functionality at J6 pin1. there should be a sawtooth here going from 5V to 12V.
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Post by nicdro » Wed Aug 02, 2017 12:59 pm

Now i had time to get back to this little one.
No it is not a board bought from synthcube.
I swapped all Caps to 50V as they were much lower.
I get 5V at L1 (input and output) so U1 gets and send 5V - is this right?
U2 sends 3.3 to V+ and 3V to +5V. I dont get it. Replacing U1 or U2? What do you think?
Thanks for your help.
Regulator on the Pacemaker still gets hot and after a while L1 as well.

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