Trouble with mutant hi-hats.

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neandrewthal
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Trouble with mutant hi-hats.

Post by neandrewthal » Mon Aug 26, 2013 10:01 pm

I'm stumped trying to get my hi-hats working. All they do is make the tiniest click when triggered. Most obvious things: The 4069 is not oscillating, despite being powered properly. I only checked that really quick so far because I've been concentrating on trying to figure out why the decay tuning LED is always lit no matter what.

The instructions say to set T1 so the LED just starts to light when you turn down the decay knob. I've got it set so the output of IC6B swings from about 11v to -2.5v when the decay knob is turned down. That should turn the LED from off to on shouldn't it, but it's always on.

The weird thing is that the other side of R86, the one connected from the output output of IC6B and the base of Q18 is always about +10v while turning the knob. So that would explain why the LED is stuck but shouldn't it be stuck off, not on?

I've tested Q18 ok with the diode check on my multimeter, popped in a new one anyway that I tested first with the hFE function, pinout's ok. Still the same thing. Tested for obvious shorts, the base of Q17 is about 300K ohms to ground, +v and -v. The emitter of Q18 is 567 ohms to ground (I'm running on 15v)

Any ideas? :help:
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Re: Trouble with mutant hi-hats.

Post by hexinverter » Tue Aug 27, 2013 5:57 am

neandrewthal wrote:I'm stumped trying to get my hi-hats working. All they do is make the tiniest click when triggered. Most obvious things: The 4069 is not oscillating, despite being powered properly. I only checked that really quick so far because I've been concentrating on trying to figure out why the decay tuning LED is always lit no matter what.

The instructions say to set T1 so the LED just starts to light when you turn down the decay knob. I've got it set so the output of IC6B swings from about 11v to -2.5v when the decay knob is turned down. That should turn the LED from off to on shouldn't it, but it's always on.

The weird thing is that the other side of R86, the one connected from the output output of IC6B and the base of Q18 is always about +10v while turning the knob. So that would explain why the LED is stuck but shouldn't it be stuck off, not on?

I've tested Q18 ok with the diode check on my multimeter, popped in a new one anyway that I tested first with the hFE function, pinout's ok. Still the same thing. Tested for obvious shorts, the base of Q17 is about 300K ohms to ground, +v and -v. The emitter of Q18 is 567 ohms to ground (I'm running on 15v)

Any ideas? :help:
Hiya!

When you say they only make the "tiniest click", do you mean it sounds like a hihat and it's short, or it's a clicking sound (not a hihat)?

If the latter, your problem is most likely not in the vactrol driver section. Even at the shortest decay times, you should still hear a very distinctly hihat sound out of the open hihat. So no matter the state of the vactrol circuit you should be getting sound.

Does the closed hihat work? It is unaffected by the vactrol circuit.

The decay indicator LED should turn off when it is maxed out. What voltage are you reading at the centre pin of the decay tuning trim pot? It should be around the Vf of the vactrol LED + the indicator LED but then negative, so something like -4V or so. Keep turning the trim pot until it starts to turn off, when the decay control is at its maximum. It sounds like you have tried to tune the decay vactrol with the knob at its minimum, which is wrong.

EDIT: Just re-read your post. It's not wonder the 4069 is not oscillating...the circuit calls for a 40106 :tu: The 4069 lacks the Schmitt triggers needed to make oscillation occur.
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Post by neandrewthal » Tue Aug 27, 2013 4:54 pm

Oh, derp. I meant to say 40106. I got it mixed up with the 4069 in my 909 snare. I actually had a 4016 in there, not a 40106 or a 4069 :doh: I swapped out my "broken" 40106 for one from a fresh tube and didn't even realize I had a 4016 until I was inspecting my "bad batch" of 40106s.

Now it sounds great, except the open hihat wont do anything but short decay because of my LED problem.

I actually did try to tune it the way it says in the instructions but it is impossible if the light never goes out, so I tuned it how I thought it should be by measuring the voltage on IC6B pin 7.

I just retuned it so the voltage on the center pin of the trimpot is -4v but the LED still wont go off. The real disturbing thing is that no matter what, the voltage on the base of Q18 is always 10v. If it is to ever turn off the base would have to go negative, right?

I don't see what this could be except a fucked up transistor, but I tested it before I put it in and checked the pinout on the actual transistor, not just the datasheet and it matches the silkscreen on the board. Is it possible that Q18 is supposed to go backwards to what it shows on the schematic?

Image
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Post by neandrewthal » Tue Aug 27, 2013 7:12 pm

neandrewthal wrote: Is it possible that Q18 is supposed to go backwards to what it shows on the schematic?
Ok, so I removed Q18 again and put in a socket so I can try out different things. Backwards operates pretty much the same.

With the transistor removed I get the light off and long decay on the open hat, obviously with no control over the time. On the base pin I measure +4v when the decay is at max and -10v when it is at min. Pop in the transistor again and the base is always 10v again no matter what :hmm:
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Post by neandrewthal » Tue Aug 27, 2013 9:26 pm

I started thinking differently about Q18. I was seeing the base as neutral and any negative voltage coming out of IC6b should make it conduct and any positive voltage should make it stop conducting.

Well, since the base seems to insist on always being 10 volts I realized I need more than that out of the IC to make it stop conducting. I re-tuned the trimmer so I have no more negative offset and turning up the decay knob makes the output go over 10v. Still no luck. Reversed the transistor and it works...but with a catch.

The decay pot is EXTREMELY sensitive with all the action happening around 3 o'clock.
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Post by hexinverter » Wed Aug 28, 2013 6:36 am

neandrewthal wrote:I started thinking differently about Q18. I was seeing the base as neutral and any negative voltage coming out of IC6b should make it conduct and any positive voltage should make it stop conducting.

Well, since the base seems to insist on always being 10 volts I realized I need more than that out of the IC to make it stop conducting. I re-tuned the trimmer so I have no more negative offset and turning up the decay knob makes the output go over 10v. Still no luck. Reversed the transistor and it works...but with a catch.

The decay pot is EXTREMELY sensitive with all the action happening around 3 o'clock.
Ah yes. Your trimmer was tuned the wrong way then. You got it working now!

It is quite sensitive, so you know it's working right now! I'd suggest changing the base resistor going to Q18 to get better control if you don't like it. It will greatly improve the response. Change R86 to 470k or 1M. This is a change I realised after designing the module. :tu:
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Post by neandrewthal » Thu Aug 29, 2013 1:03 pm

hexinverter wrote: Ah yes. Your trimmer was tuned the wrong way then. You got it working now!
But the strange thing was that it wouldn't work no matter how I set the trimmer or the knob, to either extreme, until I put the transistor in backwards.

I changed R86 to 1m and it's still sensitive but much more manageable.

Thanks for making this awesome projects! I'm having lots of fun as you've already seen. It's amazing the variations in rhythm you can get out of this thing while changing the decay, having some hits cut short by the closed hat and some triggering together.
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Post by hexinverter » Thu Aug 29, 2013 2:08 pm

neandrewthal wrote:
hexinverter wrote: Ah yes. Your trimmer was tuned the wrong way then. You got it working now!
But the strange thing was that it wouldn't work no matter how I set the trimmer or the knob, to either extreme, until I put the transistor in backwards.

I changed R86 to 1m and it's still sensitive but much more manageable.

Thanks for making this awesome projects! I'm having lots of fun as you've already seen. It's amazing the variations in rhythm you can get out of this thing while changing the decay, having some hits cut short by the closed hat and some triggering together.
Hmm...what type of transistor did you use? If you substituted out the BC-series for, say, 2N3906, the pinout is completely different!

The schematic and PCB silkscreen are most definitely correct :tu:

You're welcome! It was a fun project to make, and yeah, it is really enjoyable to play with!!! :D
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Post by neandrewthal » Thu Aug 29, 2013 3:40 pm

I used BC560 and I verified the pinout. If the pinout on the board is correct then my Hi-hat is technically broken but I bypassed the problem by reversing it and not making use of the trimpot at all. It's tuned to apply no offset to IC6Band if I tuned it to more than a couple of volts the light would never go of again. Anyway, works for me :mrgreen:
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Post by The Big Ear » Sat Aug 31, 2013 5:30 pm

neandrewthal wrote:I used BC560 and I verified the pinout. If the pinout on the board is correct then my Hi-hat is technically broken but I bypassed the problem by reversing it and not making use of the trimpot at all. It's tuned to apply no offset to IC6Band if I tuned it to more than a couple of volts the light would never go of again. Anyway, works for me :mrgreen:
I had the same problem. So I just tried what neandrewthal did, reversing the transistor, and now it's working.
Very strange...
Thanks neandrewthal, this post of yours saved me some time troubleshooting.

Cheers,

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Post by hexinverter » Sun Sep 01, 2013 3:54 am

The Big Ear wrote:
neandrewthal wrote:I used BC560 and I verified the pinout. If the pinout on the board is correct then my Hi-hat is technically broken but I bypassed the problem by reversing it and not making use of the trimpot at all. It's tuned to apply no offset to IC6Band if I tuned it to more than a couple of volts the light would never go of again. Anyway, works for me :mrgreen:
I had the same problem. So I just tried what neandrewthal did, reversing the transistor, and now it's working.
Very strange...
Thanks neandrewthal, this post of yours saved me some time troubleshooting.

Cheers,
Now that is intriguing x___x mine works fine with the schematic specified, but maybe this will require some further investigation... :woah: :deadbanana:
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Post by billieblaze » Sat Sep 28, 2013 12:46 pm

I'm having a similar problem with my open hihat, but a little different..

OHH presents a "click" on trigger.. OHH audible on CHH track w/o envelope control (PSSSSSSSSSSSSHHHH).. CHH works fine (exceot for the 2nd bit about OHH playing on that output)..

I've tried reversing the q18 (i'm using 559).. and fwiw, i'm at 15v and have replaced the relevant resistor as spec'd by the instructions.

thoughts?

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Hex Inverter Mutant Hats - DIY Issues Fizzing Open Hat

Post by nickmccall » Wed Nov 12, 2014 3:56 pm

Hi, Newbie DIYer (and modular!) here.

Having issues with my newly built hats module, the closed hat seems to work ok but the open has a noise (sometimes constant) over it, a horrible fizzing clipping sort of sound and the LED (acc) seems to flash even with no trig input?

I have't a clue which components to start checking. They all look correct and the correct way round etc.

Any ideas genius wigglers?

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Sorted! Thanks Hex...

Post by nickmccall » Fri Nov 14, 2014 9:38 am

Was a dodgy little short on one of the headers. Working now :)

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Post by recognizr » Wed Feb 03, 2016 5:32 pm

I've been trying to find what's going wrong with the open hihat without any luck.

https://dl.dropboxusercontent.com/u/379 ... broken.mp3

The sample plays CH without filter, CH with filter, OH with filter and OH without filter. Sounds like the shared noise generator and variable
band pass filter works somewhat as the CH sounds good to me. This lead me to believe that it's the second fixed and unique
band pass filter that is the problem. However, I've tried to change the parts that could be potentially broken there without any luck.

I've had some problems with the connection between the layers that I think I've fixed (among them an unreliable ground pin that made the
voltage regulator output too high voltages).
Anyone suffered from the same issue?

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