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[BACK AGAIN] Eurorack: Haible Living VCOs by R*S
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2, 3 ... 12, 13, 14, 15  Next [all]
Author [BACK AGAIN] Eurorack: Haible Living VCOs by R*S
Starspawn
Lemmy wrote:
Ah! You're a genius! My print out is of the 2016 board with the resistors reversed. d'oh!
Though I did match the resistors in the lower part of the board to the 2017 update for the HF trimmer bypass.

I will do some desoldering and see what happens.


Im not so sure about this. I have the 2016 version, and although Ive yet to do the panel wiring, I can clearly see that the righmost resistor is R30 going straight from the transistor, and R32 is the leftmost.
This is also correct from the updated designator and values from 2015 PCB (2016 mark was just 2nd run of the 2015 ones as far as I can tell.)

So 6.2K right and 1M left should be right going from Jurgens Schematic, but your non 10K R34 might have been the culprit if youre running on 12V
303ish
Thanks man, I swapped R30 and R32 again and got a perfect square! So in the end I just changed R34 to 10K and kept the trimmers (they are adjusted fully ccw tho), everything else is matching the 2016 instructions.

PW knob and PWM CV now go full range but never fade away, exactly as it should be.

Everything calibrated and running, just the oct up/down trimmers seems to do nothing...
Starspawn
Thats good smile
R140 was also changed and is relevant to the octave switch, that part isnt complicated, the 100K trimmers is just to finetune the octave jumps.
If main tune works its just a few parts to check.
If they do nothing Id think a change of R140 to 150K should help.

Edit: Another clarification for anyone soon to power up theirs. BOTH power connectors have negative bottom and positive top. I see theres been some confusion about that since the picture is of the leftmost.
prune
HI, I just got my living vco's setup, I have a few problems

My PWM section isn't working - on all three of the VCOs. Ive been trying to debug it, but the original schematic on Jurgen Haible's site doesn't seem to match the board from R*S - for example, the pulse output (I have found through digging around on the PCB) comes from an op amp, not straight off the diodes. The schematic also doesn't match the designators on my board

it's quite hard to debug when neither the schematic is the same nor the designators. Does anyone have an up-to-date schematic? Did I miss something? I feel like there should be another piece of information here somewhere

EDIT: Just read the thread and changed the resistors 30 and 32 and have a good square wave. However I am also trying to resolve the spikes..
Starspawn
While Im here.
Just finished wiring up mine and all works as it should.
However the vibrato LFO is waay to slow for my taste, has anyone experimented with changing the 47nf capacitor?
sduck
Is your Vib speed knob not working? What range are you getting from it?
Starspawn
Sloooow to some vibrato, nothing like what I would consider fast, not even 200ms Id think.

I do however have my own panel, and my rate pot is B10K like the original schematics. I dont know what designators the pots are in RS frontpanel as I dont have it, but as its not mentioned in any change schematic I can only assume its the same.
sduck
Mine goes from 1.75 hz to 10.6 hz, which seems like a good musical range to me.
DabiDabDab
Just built mine. Lin detune control doesnt change the pitch at all, at all, not a cent, on any of the 3 oscillators.. any idea what i could check? Everything else works fine so it shouldnt be so hard to isolate the issue, i wager!? The original schematics is hardly of any help here sad

Thanx for the input!
CliffordMilk
I’m halfway through my Euro version build. My main board has 2015 printed on it.

Reading through this thread, I’m now a little unsure as to the correct orientation of the transistors. Do I follow the PCB design and line up the curved markings with the curved surface of the component or is there another indicator? If there is, I can’t see it seriously, i just don't get it
Lemmy
I don't know about the 2015 board, but on mine there was an E next to where the emitter pin should be. The curve shape on my PCB was misleading and I installed the transistors the wrong way at first because of that.
2015 board is probably different though - do you have a pic?
CliffordMilk
Thanks - I’ve just seen the ‘E’ is marked on the PDF of the board with the component layout. It looks slightly different to mine but close enough that it should be good.
pix
I got asked by another wiggler if I had solved my issue with with vibrato and it was because I forgot to solder one of the pins of the IC.
CliffordMilk
Just finished my build and all seems good apart from the Drive pot doesn’t seem to affect the sound at all. It may be a stupid question but does a signal need to be patched into the VCA for this to have an effect?

If not, I have some debugging to do. Any suggestions?
nurbivore
CliffordMilk wrote:
Just finished my build and all seems good apart from the Drive pot doesn’t seem to affect the sound at all. It may be a stupid question but does a signal need to be patched into the VCA for this to have an effect?


Yeah, the drive knob only affects the signal coming out of the VCA.
schwittersplayspop
Here's my almost but not really working build using the 2017 PCB:




Right now on all three oscillators I've got fairly unsatisfactory waveforms. The pulse and saw waves are about 0.25V pp, while the triangle and sine are a bit better, at 3V pp. The pulse and saw waveforms look roughly OK, but the triangle and sine look more like square waves than triangle/sine. They're both almost the same waveform, though to the ear, the sine is slightly softer.

(Although I think I had the Q7 NPNs the wrong way around initially, changing their orientation didn't change the sound. The picture shows them after the change of orientation.)

I've played with the 2x triangle and 2x sine trimmers but haven't found them capable of getting me away from this basically square-ish waveform.
schwittersplayspop
Here are the outputs of one oscillator (the other two are the same as this on all four outputs: very weak saw and pulse, stronger triangle and sine that look square-ish).

If anyone has ideas about what could be shared across all three oscillators causing these problems I'd be grateful. Thanks!

Sine:



Triangle:



Saw:



Pulse:

Leverkusen
I find your soldering and the way the components are placed looking a bit casual und would check for components that might accidentally touch each other with their legs first, then go over the joints again.

It sounds as if it is the same fault on all three oscillators so chances are you have one or more components placed wrongly on all three while populating. So you might check every component.

When I built mine I used the schematics to look for points where I could grab the signal with a scope to narrow down the parts of the circuit I had to check more sorrowly.

I had some problems with leaving out the trimpot you bridged too, but cannot really remember. It got better though when I installed the trimmer.

Also I don't think that I put a wire link to what looks like R397.
schwittersplayspop
Thanks for your reply, Leverkusen. My soldering technique needs some improvement, though I can say I've managed to build dozens of modules successfully. Although certainly sometimes a bit of reflow has been necessary!

Given the systematic issue across all three oscillators, I agree with your prediction that one or more components is wrongly placed. Or perhaps just as likely in this case, misreading the current BOM PDF has led to me using an incorrect component.

I went for 12v values as described in the BOM, and used the Mouser cart posted early in this thread. That required some supplementary ordering as certain values seem to be for older versions of the board.

I also followed the instructions for PWM here:

http://randomsource.net/haible/lvcos/Living_VCOs_PWM.png

Which is why I have a link across R39X, R39Y and R39Z.

The trimpot bridging is currently recommended as well.

I'll begin the per-component checks.
CliffordMilk
Could someone please tell me which way round R30 and R32 go on a 2015 board?

Everything is working well but I’m getting micro spikes on all waveforms on all three oscillators.

Perhaps someone else has used boards marked 2015 and solved this another way?

Any help would be much appreciated.
Starspawn
schwittersplayspop wrote:


Given the systematic issue across all three oscillators, I agree with your prediction that one or more components is wrongly placed. Or perhaps just as likely in this case, misreading the current BOM PDF has led to me using an incorrect component.


I think it is more likely that one of the ICs are bad and used in all sections, did you source any of the opamps or ICs on Ebay?
schwittersplayspop
Starspawn wrote:
schwittersplayspop wrote:


Given the systematic issue across all three oscillators, I agree with your prediction that one or more components is wrongly placed. Or perhaps just as likely in this case, misreading the current BOM PDF has led to me using an incorrect component.


I think it is more likely that one of the ICs are bad and used in all sections, did you source any of the opamps or ICs on Ebay?


Everything is from Mouser, and was installed into a pre-soldered socket.

I am not using as many OPA2134s as is currently suggested, though. I have some TL072s because of the older cart I used. In the oscillator sections I have OP2134 in IC1A, IC1B, and IC1C and TL072 in IC7A, IC7B, and iC7C. But am I right that OP2134 and TL072 are equivalent enough to not be the issue here?

Still, I am happy to follow up any line of thinking at this point. I'm curious why you think the opamps and ICs would be the most likely issue? Thanks.
mcbinc
I haven't built a living vco yet (have built other JH designs) but... assembly is an issue. Trim the leads - from the shadows, it looks like some are half as long as the header pins. Then clean the flux and post some higher resolution and better lit photos here. I'd swear there was a short at the top of the middle VCO on the component side and a lot of possibles elsewhere.
schwittersplayspop
Current work in progress pics posted. No appreciable change in the waveforms after a lot of re-flow work. I haven't got anything around to clean flux, but I'm still going to post pics as I feel I've done a further round of work here with several sessions of re-flow and lead trimming (I didn't find any shorts in that process).

I still have the dubious re-placed Q7 NPNs (you can see them looming up tall from the board), which I had reversed at first (before I made my first post). I realize this is dodgy but I don't want to re-work that part of the board too much more before being sure it is the likely issue, as I'm worried about damaging it.

Given the consistency of the problem across all three oscs I'm still inclined to think it's bad chips or a bad/wrong component placed consistently.





I'll get something to clean the PCB in places if I need to post pics again. But in the meantime I'll probably order some more chips to test, and possibly also try to do a better job on the Q7 NPNs.
woodster
Have you checked for continuity between the top and bottom pcb's via the headers, to make sure the pin header soldering is OK ?

I know that some of the pcb interconnect pads for some Random Source PCB's can be very hard to get decent solder wetting without using additional flux, and bumping up the soldering iron temperature a bit.
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