Presenting: Crowminius

p4rancesc0 · Post by **p4rancesc0** » Mon May 29, 2017 10:49 am

Godric wrote:For what it's worth here is a pic of my crowminius build - a bit of a pig's ear but there we are.

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very nice build !! where did yuo get the pitch and mod wheel if I may ask ?

johnnyquest · Post by **johnnyquest** » Thu Jun 01, 2017 12:31 pm

Yes, I second that question and agree a very nice build! Good Job!

Troubleshooter · Post by **Troubleshooter** » Thu Jun 08, 2017 2:00 am

Hi all, ordered a bare board last week. Looking forward building it.

Planning to do an as good as possible scale replica (woodwork, panel, keys, left hand). I have a real D for measuring up things. I hope the board will fit it there somewhere (maby underneath the keys). I have a hobby cnc for engraving, milling the plastic mod wheels and so on.

I hate to solder wires directly on the board so I am allready looking for a connector to mimmic the slide switches. 2mm standard 2x3 connectors are out there but the switches seem to be a mix of 2mm and 2,5mm. Any suggestions? Maby I have to go for a seperate pair of 1x3.

Also a 44 keybed will be a challenge...Anyone experience with cutting down a larger keybed?

Godric · Post by **Godric** » Wed Jun 14, 2017 6:06 am

A very well-known (almost ubiquitous) digital synth from the early 80s donated the wheels for my Crowminius build.

While we are on the subject I am a bit puzzled by the spec for the modulation wheel VR16.

The BOM says '50k linear taper' however the digikey part number referenced is actually for a log taper pot. The PCB overlay say B5k, which is different again, a 5k linear.

Anyone built this section already? What works/is correct?

Regards

Godric

Godric · Post by **Godric** » Wed Jun 14, 2017 6:13 am

Godric wrote:A very well-known (almost ubiquitous) digital synth from the early 80s donated the wheels for my Crowminius build.

While we are on the subject I am a bit puzzled by the spec for the modulation wheel VR16.

The BOM says '50k linear taper' however the digikey part number referenced is actually for a log taper pot. The PCB overlay say B5k, which is different again, a 5k linear.

Anyone built this section already? What works/is correct?

Regards

Godric

PS the minimoog manual suggests "50k Audio" - by which I take to mean log taper.

Troubleshooter · Post by **Troubleshooter** » Thu Jun 15, 2017 8:29 am

HI, still waiting for the board to get shipped, didn't receive any update since I ordered 2 weeks ago. Iguess the old crow is a busy man. In the meanwhile I vectorized an original frontpanel layout that I will engrave on me hobby cnc.
Since I never found any good Moog font in vector format I will compromize into something diffrent. Never mind the colors thats just for multiple layering.

I still have to change it for the extra bells and whistles found on the crowminius. Any sugestions on the location for the PWM's without changing the total size? I can use the layout from the reissue for the modulation switches (LFO and VCFEG).

Troubleshooter · Post by **Troubleshooter** » Thu Jun 15, 2017 12:18 pm

This is what I got so far:

Troubleshooter · Post by **Troubleshooter** » Fri Jun 16, 2017 12:21 pm

A question, some half of the crowminius fronts I have seen have the reverse saw on OSC3 the other half have the 3 times the same saw/tri mixed waveform. Wich one should I engrave for the rev.3 board?

oldcrow · Post by **oldcrow** » Sat Jun 17, 2017 3:15 am

Hi, I am awaiting delivery of the boards which were delayed three weeks from the board house. I will be sending out a notice for boards currently on order.

To answer this question this was me forgetting to change the panel graphic to the reverse saw on osc3. This is only on a few of my early panels.

Crow
/**/

Troubleshooter wrote:A question, some half of the crowminius fronts I have seen have the reverse saw on OSC3 the other half have the 3 times the same saw/tri mixed waveform. Wich one should I engrave for the rev.3 board?

Troubleshooter · Post by **Troubleshooter** » Sun Jun 18, 2017 10:40 am

Finished the faceplate and measured and milled out some mod wheels

Godric · Post by **Godric** » Mon Jun 19, 2017 11:18 am

Troubleshooter · Post by **Troubleshooter** » Mon Jun 19, 2017 4:26 pm

Godric wrote:

Nice desktop build man!

Troubleshooter · Post by **Troubleshooter** » Tue Jun 20, 2017 7:57 am

Left hand controller taking shape.

Godric · Post by **Godric** » Thu Jun 22, 2017 5:44 am

I think I'll call it the coffin, as that's what it looks like from the side:

Troubleshooter wrote:
Godric wrote:
Nice desktop build man!

JanneI · Post by **JanneI** » Fri Jun 30, 2017 4:05 pm

Help needed troubleshooting my crowminius build.

Oscillators work, but no sound after the mix bus. I get all the waveforms from all the oscillators, PW&PWM works. Octave switches have -5v at "2, -4,5v at 4" etc, but after the cv-summer scaling is way off. Pitch wheel has to be more at the +10v end to get the oscillators audible rate and then octave switch at only 4" will drop the pitch under the audible rate. I still see oscillation happening on the scope..

I put jumpers (T-TS) at J2, J3, J13, J14 (jacks not mounted). Midi/usb not yet mounted. I get the proper +-10v, phase led ok. I get a quiet 440hz from the main output, so atmega should work? VCA makes a click sound when triggered (VCA offset I guess), so env's and VCA should work?

It still could be my wiring, but I did take time building and double checked everything. I now even tested it with only the neccessary switches and pots for osc1 and the it behaved the same way.

Could someone point me to the right direction? Proper voltages? Crow's schematic page3 is a little bit over my league, so it's hard trying to isolate things to make sure whats ok and whats not.. And why I'm not getting anything through on the main output?

Thanks!

oldcrow · Post by **oldcrow** » Fri Jun 30, 2017 8:39 pm

Make sure you have the switch lug of the external loudness jack taken to +10V through a 33K resistor. The VCA will be off otherwise. --Crow

JanneI wrote:Help needed troubleshooting my crowminius build.

Oscillators work, but no sound after the mix bus.

JanneI · Post by **JanneI** » Sat Jul 01, 2017 12:37 am

Thanks, that jumper (loudness jack) gives me +7,7V, so it should be ok, right?

I get a really quiet 440Hz (from the ATMEGA) from hi output and phones and either of the VCA balance trimmers don't have any effect, should they? How could I first make sure that the VCA works?

oldcrow wrote:Make sure you have the switch lug of the external loudness jack taken to +10V through a 33K resistor. The VCA will be off otherwise. --Crow

JanneI wrote:Help needed troubleshooting my crowminius build.

Oscillators work, but no sound after the mix bus.

JanneI · Post by **JanneI** » Sat Jul 01, 2017 1:04 am

I have approx 3v peak-to-peak from the oscillator out switch pin2, this should be ok?

R177 - C22 junction is the vca input, right? Could I insert the osc output directly there (disable the filter completely)?

p4rancesc0 · Post by **p4rancesc0** » Fri Jul 07, 2017 10:04 am

Wow, the panel looks amazing!

Where did you get the mod and pitch wheels ?
Are you going to share the project files ?

Thanks
BR

Troubleshooter wrote:Finished the faceplate and measured and milled out some mod wheels

JanneI · Post by **JanneI** » Mon Jul 10, 2017 1:43 pm

I think my problem is the VCA, because I do get a proper sound out of the filter after the R177. 440hz can be heard very very quietly but nothing else comes through the VCA. I soldered a jumper to loudness jack (J2), switch to tip. I checked the transistors for mixing npn pnp, but they are all correct. Any idea how to solve this? Voltages to measure?

JanneI · Post by **JanneI** » Tue Jul 11, 2017 12:36 pm

Some progress. I grounded the S-trig and got the envelopes working, yay! So VCF&VCA are ok. Gate from the midi in started triggering the envelopes after I soldered the tx led. J2, J3, J12, J13, J14, J16 jumper from the T to TN (no jacks).

Still, CV from the midi is totally out of control. IC25 pin 5 (LF398, 6A_KBD) gives me reasonable good voltages when playing the midi keyboard, but oscillators go way, way off, on the limits of the hearing area. Octave switches make the -5v with 0,5v steps on IC2B pin7, pin8, pin14, but oscillators make hearable sound only at 2feet, highest octave setting on all oscillators. Pitch wheel and tune have a way too wide range (from LFO area to "not hearing anything anymore").

I guess i tried to be too clever with the "I can leave that unsoldered for now". Anyway, progress happening even thought not quiet there yet...

JanneI · Post by **JanneI** » Tue Jul 11, 2017 5:25 pm

After reading this whole thread, I measured the R24A, R64A, R102A, just to be sure, and found out that osc1 did give me a proper 1k ohms but the osc2 and osc3 gave 100k

So I guess that needs to be fixed tomorrow. Hopefully this will make things all good.

JanneI · Post by **JanneI** » Wed Jul 12, 2017 5:17 am

Tempco's fixed now, but one more thing still remains.

I'm using midi, R4 is 102k, but still playing just 2 octaves gives me "LFO clicks -> "so high that I'm not hearing anything anymore"-area". R4 gives me voltage steps that I consider to be correct. Octave switches have way too large scale, only switching to one step lower makes oscillator go to LFO area, even though I get -5V (and 0,5V steps) from the LM348 (7,8,14 pins). Pitch wheel is set to middle, +5V. Scale trimmers R16,R55,R91 works in a way that both ends (low and high keys) move to higher or lower, which I found a little strange...shouldn't this make lows go lower and highs go higher?

here's a video:

Troubleshooter · Post by **Troubleshooter** » Tue Jul 18, 2017 7:23 pm

Getting there slowly. Board on the way, fingers crossed for import taxes

Gonne mount the crowminius board underneeth the keybed upsidedown and clamp the cables into the right bending angle towards the rotating knob surface.

p4rancesc0 · Post by **p4rancesc0** » Fri Jul 28, 2017 10:06 am

Hi,
sorry to bother but is there any chance to get in Europe (Italy) this opto coupler ?

PC900V0NSZXF

Even a replacement would be fine if there's any...

Thx

MUFF WIGGLER

MUFF WIGGLER

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