[BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

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StrangeAttraction
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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by StrangeAttraction » Tue Feb 11, 2020 7:21 am

Hi,
Hope you can help.

I bought a some-dude-built version of the Humpback and it's been working fine for a while...until quite recently when it developed issues.
In short, the filter appears to be stuck in a high resonance setting, in that unstable Waspy territory.
I've made a video showing this odd behaviour. Below are the screenshots of the build.

The only thing about the build that looks off to me is that piece of wire connecting 10uF capacitor with a solder in the last picture (shown with a yellow arrow).
Don't know why it's there, but it's been there while the module was working fine.
Any suggestions on what the issue might be?


Images:
Image
Image
Image
Image
Image

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cnicht
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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by cnicht » Tue Feb 11, 2020 7:50 am

It's probable that the wire link was put in because of a broken track.

There seems be some poor soldering of the long board to board connector by the power connector, worth going over the joints with a little more solder.

Also try removing the black jumper from the back of the board it may tame the resonance, I do not have it placed on my two.

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Re:

Post by Galv » Thu May 14, 2020 5:05 pm

JP8 wrote:
Sun Dec 30, 2018 7:55 am
I finished my build. First it didn’t work. I only got a soft sound passing through without any filter action. So I took it apart, resoldered all joints and double checked the headers as suggested in this thread. I also replaced all the ICs. I put it back together but still no change. The frequency knob seems to act like a volume pot...

Any help would be appreciated. Picture of the build enclosed.

Cheers,
Ricardo[/img]
I have this same problem, as mentioned by a few others too.

Freq. knob acting a bit like a volume control, no filtering. Resonance knob doesn't do anything; with the jumper on and turned up to max it resonates with a harsh square wave sound.

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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by etsuko92 » Thu May 21, 2020 3:47 am

Hey, I've received the panel and pcb from Thonk this week. I'm buying the other components from Mouser. The BOM states mouser no. ECQ-V1J334JM for a 0.33uF poly film capacitor, but this product isn't made anymore. I wonder if I could use ECQ-E2334JB as a replacement?

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sir stony
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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by sir stony » Thu May 21, 2020 3:52 am

Electrically, yes, but the size, man! I doubt you'll manage to fit it in there. Look for polyester capacitors with lower voltage.

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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by etsuko92 » Fri May 22, 2020 5:39 am

Thanks! Hadn't looked at the size... I've found a few other options:

598-334MMR100K

This one has 10% tolerance instead of 5%. I'm not sure how that affects the circuit.

75-MKT1818433014

This one has short legs, not sure if easy to solder. Also not sure if "AC and Pulse Film Capacitors" is the right product type?

There's also some more options but they have 5mm lead spacing instead of 7.5mm which might not fit.

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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by sir stony » Fri May 22, 2020 1:41 pm


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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by _marrs » Sun May 24, 2020 5:43 am

Hello. I just built the DIY kit of the Humpback and as lovely as it was to build and I'm pretty sure (and double checked) that my build is correct as the kit was beautifully put together for an idiot like me I seem to be having some problems. The Cutoff filter is acting more like a volume knob instead of a filter. The res knob is ok then all of a sudden brutal. The jumper pin on the rear is on.
Here are some images of my build and (hopefully a video)
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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by cranleigh » Wed May 27, 2020 5:03 pm

When I built mine, the LP and BP modes didn't pass signal, and the other modes just acted like a volume control. The answer was to replace a dodgy CA3080, so that might be worth a try? The first one I had looked legit but it turned out to be defective or a fake and replacing it brought the filter to life.
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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by _marrs » Thu May 28, 2020 1:34 pm

Thanks for the reply.
I'll have to have a dig around to see if I've got any and give it a try.

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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by _aghughes94 » Wed Jun 03, 2020 7:01 am

_marrs wrote:
Sun May 24, 2020 5:43 am
Hello. I just built the DIY kit of the Humpback and as lovely as it was to build and I'm pretty sure (and double checked) that my build is correct as the kit was beautifully put together for an idiot like me I seem to be having some problems. The Cutoff filter is acting more like a volume knob instead of a filter. The res knob is ok then all of a sudden brutal. The jumper pin on the rear is on.
Here are some images of my build and (hopefully a video)
I've just finished building one and have exactly the same issue. Did you purchase from thonk's latest batch? Wondering if we share the same faulty chip potentially.

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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by _aghughes94 » Wed Jun 03, 2020 4:42 pm

Contacted Thonk regarding the issue and was passed on to God’s Box and they’ve suggested removing the FET’s and putting back in the wrong way round, I’ve just knackered one of the legs desoldering though so waiting on a replacement before I can test but worth a try if we’ve got the same problem.

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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by jonny_w » Thu Jun 04, 2020 10:04 pm

I just ordered the kit from Thonk...I'm eager to see what you guys find.

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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by GodsBox » Fri Jun 05, 2020 5:19 am

Hi everyone, we are working on a solution to this problem. On the run of kits starting in May 2020 it looks like we got a dodgy batch of 2n3819 FETs

I fixed one of these boards and I replaced the FETs with new ones and it worked fine - if it's an option for you to get some new FETs, then it's the ON semiconductor pinout, NOT the Fairchild pinout. I understand that sourcing them and ordering them is a pain and I only suggest it in case you order parts regularly and want a quick fix

Please hold tight while we try and think of the easiest thing we can do
Last edited by GodsBox on Wed Jun 10, 2020 2:58 am, edited 1 time in total.

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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by jonny_w » Sun Jun 07, 2020 11:43 pm

Thank you for letting us know. I haven't received the kit from Thonk yet, so I'll try reversing the FET's and report back on the forum post if it works.

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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by Naenyn » Tue Jun 09, 2020 11:58 pm

Man, wish I would have read this thread before building mine tonight. Now to see if I can get those FETs turned around...

EDIT:
GodsBox wrote:
Fri Jun 05, 2020 5:19 am
So, in the short term please try reversing the FETs.
I was able to reverse my FETs. The module sounds .. better than before. However, it still isn't right. As others mentioned, I'm experiencing what sounds (and looks, in a scope) like a square wave with an open LPF with max resonance.

I guess the next step is finding new FETs? Hopefully that's all that is wrong with my build...

EDIT #2:

So, Mouser shows that the ON Semiconductor version is obsolete. The only one they list in stock is from Central Semiconductor. Will that one work? I have no idea on this sort of thing...

EDIT #3: :goo:
There's also one from NTE Electronics at digikey... :despair:
-n :ninja:

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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by Thonk Support » Wed Jun 10, 2020 2:47 am

Hi all,

It looks like the reverse FET idea isn't actually the case and that we were sold simply defective parts. Please note this only affects kits ordered since March 2020, we think 12 kits in total possibly affected. We're contacting everyone affected to resolve. The good news is regardless of fitting these parts, we've not seen any damage caused elsewhere in the circuit and refitting the correct parts will solve the issue.

See the photo below to identify the possibly problematic kits, all from batch 1287.25

Cheers

Steve
Screenshot_20200610-093528.jpg
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Last edited by Thonk Support on Wed Jun 10, 2020 4:07 am, edited 3 times in total.
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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by Thonk Support » Wed Jun 10, 2020 2:48 am

Naenyn wrote:
Tue Jun 09, 2020 11:58 pm
Man, wish I would have read this thread before building mine tonight. Now to see if I can get those FETs turned around..
Naenyn, we'll send you the correct parts DM us, this won't have broken anything don't worry.
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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by GodsBox » Wed Jun 10, 2020 2:59 am

Ive now edited my previous post now we know that the batch of FETs is in fact defective

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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by Thonk Support » Wed Jun 10, 2020 4:05 am

More info on the kits affected by the defective 2N3819, I now have worked out it's only 12 kits in total possibly affected. Emailing everyone who could be affected now.
Screenshot_20200610-093528.jpg
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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by Naenyn » Wed Jun 10, 2020 1:08 pm

Monobass wrote:
Wed Jun 10, 2020 2:48 am
Naenyn, we'll send you the correct parts DM us, this won't have broken anything don't worry.
You've got me sorted via email. Thank you!!
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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by jimlacube » Sat Jun 27, 2020 11:55 am

Hi,
I just finished building the filter and it doesn't seem to be functioning as expected. It seems to be constantly self-oscillating and doesn't seem to be affected by the input.

Does anyone know how I can fix this issue?
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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by Thonk Support » Sat Jun 27, 2020 12:11 pm

jimlacube wrote:
Sat Jun 27, 2020 11:55 am
Hi,
I just finished building the filter and it doesn't seem to be functioning as expected. It seems to be constantly self-oscillating and doesn't seem to be affected by the input.
First thing I noticed is it looks like there is an unsoldered connection on one of the minijacks

Screenshot 2020-06-27 18.01.14.png

Also a warning sign for cold solder joints is there are a LOT of components where the solder isn't making it even half way through the board and you can see these unfilled holes, like on these resistors.

Screenshot 2020-06-27 18.03.07.png

This would suggest either your tip is quite worn out, or your iron isn't hot enough for the solder you're using or that it might be worth a refresh on your technique.

Dull rough solder joints like this, rather than smooth and shiny are typical of cold joints too.

Screenshot 2020-06-27 18.05.50.png

The Adafruit guide to Excellent soldering is a really good resource
https://learn.adafruit.com/adafruit-gui ... n-problems

Image

The key thing you can see from this image is that you should be seeing solder getting through to the other side, boards can still work if there are some joints which don't look like this, but when there are so many that don't it sets the alarm bells ringing.

Image

You should probably remove the IC's and look at reflowing all the joints to be honest, but you might want to consider whether this is an issue with your tools (need a new tip for example) before diving into that.
You do not have the required permissions to view the files attached to this post.
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AS of October 2020 this account which used to go by the name of Monobass is now manned by various staff at Thonk.

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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by jimlacube » Sun Jun 28, 2020 6:58 am

Monobass wrote:
Sat Jun 27, 2020 12:11 pm
jimlacube wrote:
Sat Jun 27, 2020 11:55 am
Hi,
I just finished building the filter and it doesn't seem to be functioning as expected. It seems to be constantly self-oscillating and doesn't seem to be affected by the input.
First thing I noticed is it looks like there is an unsoldered connection on one of the minijacks

Screenshot 2020-06-27 18.01.14.png

Also a warning sign for cold solder joints is there are a LOT of components where the solder isn't making it even half way through the board and you can see these unfilled holes, like on these resistors.

Screenshot 2020-06-27 18.03.07.png

This would suggest either your tip is quite worn out, or your iron isn't hot enough for the solder you're using or that it might be worth a refresh on your technique.

Dull rough solder joints like this, rather than smooth and shiny are typical of cold joints too.

Screenshot 2020-06-27 18.05.50.png

The Adafruit guide to Excellent soldering is a really good resource
https://learn.adafruit.com/adafruit-gui ... n-problems

Image

The key thing you can see from this image is that you should be seeing solder getting through to the other side, boards can still work if there are some joints which don't look like this, but when there are so many that don't it sets the alarm bells ringing.

Image

You should probably remove the IC's and look at reflowing all the joints to be honest, but you might want to consider whether this is an issue with your tools (need a new tip for example) before diving into that.
Thank you for the advice. I resoldered all of the pads and the module is working perfectly now. Cheers!

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Re: [BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by Thonk Support » Sun Jun 28, 2020 11:42 am

jimlacube wrote:
Sun Jun 28, 2020 6:58 am
Thank you for the advice. I resoldered all of the pads and the module is working perfectly now. Cheers!
Great news :sb: :goo:
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