Soma - LYRA-8 DIY Kit

[neilarmstrongmuseum]

I asked Vlad about it back when I was putting together my Lyra-4. This was his reply:

"This is a choke 220 - 470 mkH
you need one with low internal impedance < 1.5 Ohm
Or you can easy short it if you have a good PSU"

Awesome. Thanks so much!
What is "mkH"? Is that Russian for millihenry or microhenry? or megahertz?

[Flounderguts]

Vlad uses m instead of u for mu.

I think the k is a typo

[modifikator]

https://cloud.mail.ru/public/FRZa/kUBkLsrVi
https://cloud.mail.ru/public/7RuN/KpcCdu2th

There is a chip on the left from the Lira-8 DIY Kit and the chip on the right one bought by me in the store. There is no dot on the chip on the left, dot here on the chip on the right! Perhaps this will help someone when installing the chip on the board in the correct way

If I understand everything correctly

[Flounderguts]

https://cloud.mail.ru/public/FRZa/kUBkLsrVi
https://cloud.mail.ru/public/7RuN/KpcCdu2th

There is a chip on the left from the Lira-8 DIY Kit and the chip on the right one bought by me in the store. There is no dot on the chip on the left, dot here on the chip on the right! Perhaps this will help someone when installing the chip on the board in the correct way

If I understand everything correctly

The bevel is always on the pin 1 side...

[Flounderguts]

Standard Lyra panels are in stock at flundrton.com! New versions as well, pix posted on the expansion panels thread.

I need to take better pix and upload the products, but they should be available for purchase within 24 hours! Also, any orders that people were waiting on were shipped as soon as I woke up today

[Flounderguts]

Panels tested and put into inventory! The Mandala and Helix touchpads are awesome. I like them better than the thumbscrews, TBH.

I had an idea about making a 2 part touchpad, with the lower part as usual, and the top part using the AT42QT1012 chip for a capacitive touch toggle switch. It will drive an LED as well...that would be pretty tidy, wouldn't it?

Maybe I'll implement that on the gate upgrade, which needs its own 5V power rail, anyway...

[mutronic]

I just finished putting together my Lyra 8 board and the only issue I've encountered is the voice 2 pad is non responsive when pressed. Voice 2 is on hold by default and when I do press the pad it sounds like an aux cord being unplugged. When I was working on the expansion mods, I mistakenly soldered in the wrong capacitors, so the ground on the voice 2 capacitor was pulled from the bottom end of the board when I pulled it out to insert the wiring instead. But I soldered the expansion wires from the top of the board so the range potentiometer for voice 2 works fine, and pretty much everything about it is functional, including the attack/release section and vibrato on the expansions. Has anyone had any similar experiences with pads malfunctioning and found any solutions?

[edited for more concise explanation]

[mutronic]

I just finished putting together my Lyra 8 board and the only issue I've encountered is the voice 2 pad is non responsive when pressed. Voice 2 is on hold by default and when I do press the pad it sounds like an aux cord being unplugged. It is a cap I had to pull up because I mistakenly soldered in the wrong capacitors as I was building it with the expansions, so the ground on the voice 2 capacitor was pulled from the bottom end of the board. But the range potentiometer for voice 2 works fine, and pretty much everything about it is functional, including the attack/release section and vibrato on the expansions. Has anyone had any similar experiences with pads malfunctioning and found any solutions?

Also, all the voltages check out on the board.

[citizensmurf]

I've been mulling this build over for a while and reading through the thread has got me excited. Soma just put me on the waiting list, and they said "within a month or so" they should have more pcbs to sell. This long cold winter has led me to finish up some projects, so I'm looking for something else to dig my teeth into.

[Flounderguts]

Malfunctioning pads: check 3 things...the board to board connections at "pad 2," the switch connections at the "fast" switch, and the ground connections at the lower pad.

If the switch is always on, check that the upper pad or pad 2 traces aren't grounding somwhere. Easy to check with a continuity test from top to bottom pad.

[mutronic]

Malfunctioning pads: check 3 things...the board to board connections at "pad 2," the switch connections at the "fast" switch, and the ground connections at the lower pad.

If the switch is always on, check that the upper pad or pad 2 traces aren't grounding somwhere. Easy to check with a continuity test from top to bottom pad.

Thank you! I will look into this.

[mutronic]

So I checked the fast switch and everything is soldered in properly. All the connectors are connected accordingly. Ground connections on the pads are good. One thing I noticed when checking continuity was all the pads go up to around 5.7-6V, which I think is standard across the board except for pad 2, which reads at 9V.

[mutronic]

Got it! It was a top-side connection wire that was mis-matched. Thanks again for the help.

[mutronic]

OK the last thing I've noticed is voice 1 is lower in volume than the other voices, and if I turn the sharp knob all the way up it cuts it off. The sharp knob works fine with voice 2, and the voice 2 volume is the same as all the other voices.

[mutronic]

Starting to think it's just the nature of the device itself and not really a problem.

[autodafe]

I am a bit puzzled by the build guide, regarding the "Shields"

it says:
Install the shields on the bottom side of the main PCB after soldering of all other parts. Places for installation - see PCBs/Place for shields.jpg
Use UP holes for upper PCB part and DWN holes for lower one.

what do they mean by "UP for upper PCB and DWN for lower one" ????

[Flounderguts]

I am a bit puzzled by the build guide, regarding the "Shields"

it says:
Install the shields on the bottom side of the main PCB after soldering of all other parts. Places for installation - see PCBs/Place for shields.jpg
Use UP holes for upper PCB part and DWN holes for lower one.

what do they mean by "UP for upper PCB and DWN for lower one" ????

There should be 2 small bits of pcb material with your kit, so main board, control board, IO board, and 2 identical blank rectangular boards (and 2 nxp 4093's)

When you were assembling your Lyra main board, you probably noticed some through holes that were not connected to anything...near 2 of the TL074 chips. That is where these blank pcb "shields" go. The UP holes match one, and the DWN match the other. Both get mounted below the main and control boards, attached to the main.

It's not intuitive.

[autodafe]

OK, thanks a lot. Yes, I have the two small rectangular PCBs for "Shields", I just was not sure why they called them UP and DWN when they are actually one on th eleft and one on the right. Thanks for clarifying ;-)

[threedaymonk]

Vlad uses m instead of u for mu.

I think the k is a typo

I think mk is intended to mean micro.

The Russian prefix for micro is "мк", which is "mk" in the Latin alphabet. You see "mc" as a prefix for micro in English sometimes, e.g. mcg in medicine.

[autodafe]

I have finished building mine.
I have an issue on the PITCH knob for voices 5-6-7-8 (first four voices are OK)
If I turn the PITCH knob up at about '9 o clock it starts "holding" voices 5-6-7-8, and they all play together (the HOLD knob is at zero). Opening the PITCH knob more changes the pitch of the four voices as expected, but also raises their volume a bit.
Any idea on what to check? PICTH for voices 1-2-3-4 works perfectly, no "bleeding" of the voices when PITCH is moved...

[Flounderguts]

I have finished building mine.
I have an issue on the PITCH knob for voices 5-6-7-8 (first four voices are OK)
If I turn the PITCH knob up at about '9 o clock it starts "holding" voices 5-6-7-8, and they all play together (the HOLD knob is at zero). Opening the PITCH knob more changes the pitch of the four voices as expected, but also raises their volume a bit.
Any idea on what to check? PICTH for voices 1-2-3-4 works perfectly, no "bleeding" of the voices when PITCH is moved...

1st, check your board to board connections at TRNS2.
2nd, check the soldering on the #2 NXP 4093, and make sure it's not backwards or has any bridged connections.
3rd, near that NXP chip there is a 547 transistor, check the connections and the orientation of that transistor.
4th, as the voices are sounding together, with the hold pot off, check for a grounding issue last...an upside down chip would do that, but there may be a different issue. Check for continuity to gnd from the pch connections and also the TRNS2.

The voices sound when the current flows to ground...

Hope that helps.

I'm currently troubleshooting a similar issue where the pitch pot for 1-4 only has effect in the last 1/4 turn, and voice 1 is operating muted or nonexistent...seems to be a connection issue. I'm waiting for parts to try a new way of connecting the main and control boards. In the troubleshooting I have done, 99% of issues happens because of bad board to board connex, and the other 1% seems to be issues developing from the multiple rebuilds my main board has from the experiments I do!

[mutronic]

After resoldering some of the connections on voice 1, I got it working at an equal volume of all the other voices, but there are still two things that affect the voice unlike voice 2. When I turn the sharp knob all the way up, it mutes the voice, and the "fast" switch does not affect the voice at all.

[Flounderguts]

After resoldering some of the connections on voice 1, I got it working at an equal volume of all the other voices, but there are still two things that affect the voice unlike voice 2. When I turn the sharp knob all the way up, it mutes the voice, and the "fast" switch does not affect the voice at all.

The fast switch allows the 12V rail power through the release section. Check joins on all 39K resistors, I think. I don't have a board in front of me right now (I'm at work), but I think that's where you would look. I'll have to take a look at stuff when I get home.

[autodafe]

1st, check your board to board connections at TRNS2.
2nd, check the soldering on the #2 NXP 4093, and make sure it's not backwards or has any bridged connections.
3rd, near that NXP chip there is a 547 transistor, check the connections and the orientation of that transistor.
4th, as the voices are sounding together, with the hold pot off, check for a grounding issue last...an upside down chip would do that, but there may be a different issue. Check for continuity to gnd from the pch connections and also the TRNS2.

Thanks for taking the time to reply

1) board to board connection at TRNS2 seems OK, I have continuity between the control board, connector pins and the TRNS2 labeled on the main board (I have used dupont cables with one side soldered to the control board and the dupont side connected to pins on the main board)
2) the NXP 4093 are in the same exact orientation, with the slant towards the top of the main board
3) all transitors are in the right direction, already checked 1000th times
4) no grounindg apparently. I have tested all of the connection pin points and none is shorting to GND (except GND pins of course).Trns2 is not shorted. IC are all in the correct orientation...

Some more testing and troubleshooting:
I noticed that when PITCH fori voices 5-8 is turned on, voices 5 and 8 are very loud, while voices 6 and 7 are barely audible.

I have some SUSPECTS (can you confirm if they are right or not?)
1) I salvaged the 4x DPDT ON-OFF-ON swicthes from (very) old audio gear. Maybe they are not the right ones or there's a broken/shorted one?
2) at some point I am pretty sure I connected the IO Board in the opposite way, possibly shorting VCC+ and VCC-. Maybe some IC got burnt? (I have plenty of TL074 and some spare 4093, doesn't cost anything to swap them)

Other ideas are welcome ;-)

[mutronic]

After resoldering some of the connections on voice 1, I got it working at an equal volume of all the other voices, but there are still two things that affect the voice unlike voice 2. When I turn the sharp knob all the way up, it mutes the voice, and the "fast" switch does not affect the voice at all.

The fast switch allows the 12V rail power through the release section. Check joins on all 39K resistors, I think. I don't have a board in front of me right now (I'm at work), but I think that's where you would look. I'll have to take a look at stuff when I get home.

Just checked the 12v rail and it reads out 11.5v or so, but so does all the other 39ks that line up next to the attack/release area of the voices. I reflowed the top of the 39k resistor on voice 1 for the heck of it, but it didn't seem to affect the fast switch for voice 1. Also something I noticed when I measure the voltage in the designated areas, I get 5.76v for all the areas that are supposed to be 5.87v, but the 6v and 2.5v are fine. Not sure if that's far enough off to actually make a difference.