Plaits DIY

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Padrat
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Post by Padrat » Wed Dec 04, 2019 5:01 pm

Just finished a Knits and I seem to be having the same trouble as @c0ntr4d1ct10n was having with firmware flashing. Checked the mentioned problem areas but to no avail. That includes the 3.3v, 3.3v A, and did a continuity test between the header pins and the matching pins on the the stm pins. Could it be something to do with the crystal?

crawave
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Re: Plaits DIY

Post by crawave » Tue Jun 02, 2020 2:16 pm

hi, I assembled Plaits. My problem is that the AUX output does not know. using the oscilloscope I discovered that no sound comes out of pin 6 of the dac.I have reflow STM and DAC and all components including the op amp mail problem continues.can someone help me?

atch3000
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Re: Plaits DIY

Post by atch3000 » Tue Jun 09, 2020 4:26 pm

hello hello...
im assembling a Knits at this moment, i am just wondering how i should solder the jack leds and how to determine their polarity ?

Thank you!

atch3000
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Re: Plaits DIY

Post by atch3000 » Fri Jun 12, 2020 3:28 pm

atch3000 wrote:
Tue Jun 09, 2020 4:26 pm
hello hello...
im assembling a Knits at this moment, i am just wondering how i should solder the jack leds and how to determine their polarity ?

Thank you!
i have set them this way, it seemed the most logical, however no light. should i reverse them all?
the menu lights seem to work fine hopefully!
and whats that 2 pin connector on the back actually?



EDIT : found a picture, of course they are all in the wrong direction :guinness:

artparks
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Re: Plaits DIY

Post by artparks » Tue Jun 23, 2020 3:36 pm

I've assembled an Antumbra Knits but have hit a bit of a roadblock. Everything on the brain board appears to work, I've flashed it successfully (as far as I can tell - when pressing menu buttons the LEDs behave as expected, so I can only assume the software is functional), but I have no output and no response from any inputs.

I've traced the inputs through the control board and up through the jumpers onto the brain board and that all seems OK. I've tested that all the ICs are receiving the expected voltages (both 3.3 and 3.3_A where required), and I've checked under a scope for bridges on the ICs and I see nothing wrong. Well, I do have a slightly mangled pad between pins 10/11/12 on the control board 6004 which is bridged (and beyond repair) but these pins all go to ground anyway so it shouldn't matter.

I've reflowed everything and I'm at a loss! What could possibly cause all jacks, both input and output to be unresponsive? I get neither audio output, nor can I, for example, use CV to move between models.

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cnicht
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Re: Plaits DIY

Post by cnicht » Tue Jun 23, 2020 4:29 pm

Have you installed the jack sockets?

artparks
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Re: Plaits DIY

Post by artparks » Tue Jun 23, 2020 5:13 pm

Yep, it's all fully assembled. I really can't understand what would go wrong such that all jacks would be broken. Looking at the schematic, there's no common signal path for all of them (unsurprisingly).

I've never used a Plaits, but presumably it's like any VCO and I should be able to just plug into the output and hear something? I don't have to strike the trig in to make it fire? Not that that works anyway!

artparks
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Re: Plaits DIY

Post by artparks » Tue Jun 23, 2020 5:23 pm

Pictures, for what help they may be:

Image

Image

tele_player
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Re: Plaits DIY

Post by tele_player » Tue Jun 23, 2020 5:32 pm

artparks wrote:
Tue Jun 23, 2020 5:13 pm

I've never used a Plaits, but presumably it's like any VCO and I should be able to just plug into the output and hear something? I don't have to strike the trig in to make it fire? Not that that works anyway!
Yes, without any inputs, Plaits will have output on both outputs.

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cnicht
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Re: Plaits DIY

Post by cnicht » Wed Jun 24, 2020 2:32 am

Are you getting the normalisation signal at the jack inputs?

artparks
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Re: Plaits DIY

Post by artparks » Wed Jun 24, 2020 4:31 am

cnicht wrote:
Wed Jun 24, 2020 2:32 am
Are you getting the normalisation signal at the jack inputs?
Not entirely sure what to look for, but I'm seeing ~1.5v on the switch inputs of jacks 2, 3, 4, 6 and 7, which are those that should be normalised, according to the schematics. I'm not clever enough to work out from them what voltage I'm meant to see!

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cnicht
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Re: Plaits DIY

Post by cnicht » Wed Jun 24, 2020 4:49 am

There should be a PRBS signal generated by the microcontroller on the switched contact of jacks J2 - 4 and J6 - 7.

This should also be present at the outputs of the op amps which are connected, through resistors, to these jacks.

artparks
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Re: Plaits DIY

Post by artparks » Wed Jun 24, 2020 5:37 am

I don't have a scope easily to hand but I see voltages of ~1.5 to 2v on pins 1, 7 & 8 of the 6004, so the op-amp appears to be behaving and sending things though. Tracing things on, those signals should then go into pins 18/19/20 of the MCU but testing that is going to need a whole bunch of messing about running it unassembled and jumper cables between the boards so that'll take a while to set up!

That said, I've tested that the signals are making it from the front board to the brain board, so the only real fault could be in the PCB traces from pins to pads of the MCU which is super unlikely? The MCU appears to be soldered fine.

artparks
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Re: Plaits DIY

Post by artparks » Wed Jun 24, 2020 7:48 am

Checked it, and the same voltages are going into pins 18, 19 & 20. I suspect this thing is getting chucked in the bin!

Edit: some progress, turns out the inputs are most likely working and I'm just an idiot for not realising as I can now make it move between models via CV. So it feels like a fried/broken DAC?

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cnicht
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Re: Plaits DIY

Post by cnicht » Wed Jun 24, 2020 9:46 am

Does the DAC generate its own negative supply?

-3.3V on Pin 5

artparks
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Re: Plaits DIY

Post by artparks » Wed Jun 24, 2020 10:07 am

Nothing at all on pins 5, 6 or 7. I think we may be on to a winner... I've ordered a couple of new DACs.

Thanks so much for your help, hugely appreciated. Hopefully this is it.

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cnicht
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Re: Plaits DIY

Post by cnicht » Wed Jun 24, 2020 1:35 pm

I wouldn’t just assume the DAC is faulty. It may be in sleep mode and in this mode the charge pump which generates the negative voltage turns off.

It would be better to investigate the presence of signals driving it from the microcontroller.

An oscilloscope is needed.

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ntrm
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Re: Plaits DIY

Post by ntrm » Thu Jun 25, 2020 1:52 am

artparks wrote:
Tue Jun 23, 2020 3:36 pm
I've assembled an Antumbra Knits but have hit a bit of a roadblock. Everything on the brain board appears to work, I've flashed it successfully (as far as I can tell - when pressing menu buttons the LEDs behave as expected, so I can only assume the software is functional), but I have no output and no response from any inputs.

I've traced the inputs through the control board and up through the jumpers onto the brain board and that all seems OK. I've tested that all the ICs are receiving the expected voltages (both 3.3 and 3.3_A where required), and I've checked under a scope for bridges on the ICs and I see nothing wrong. Well, I do have a slightly mangled pad between pins 10/11/12 on the control board 6004 which is bridged (and beyond repair) but these pins all go to ground anyway so it shouldn't matter.

I've reflowed everything and I'm at a loss! What could possibly cause all jacks, both input and output to be unresponsive? I get neither audio output, nor can I, for example, use CV to move between models.
Have you calibrated it? Otherwise it could act strangely - although I think mine had sound before calibration.

artparks
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Re: Plaits DIY

Post by artparks » Thu Jun 25, 2020 10:49 am

Argh, trashed the board trying to desolder the DAC. New PCB ordered, fingers crossed I don't destroy this one.

collumn2016
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Re: Plaits DIY

Post by collumn2016 » Thu Jun 25, 2020 12:00 pm

HI, i made a plaits using a board from amazing synth. NO snub to them but they created a different version using has many 0603 as they could. This meant there was some confusion in one specific area of which part was which around the output ic. i bet veterans wouldnt have made the mistake i did but there you go lol!I was wondering how different the layout you have is from the original and whether there was any confusion for you? I swapped a capacitor for a resistor by misreading the labelling, i had little if any output and distortion. I doubted everything i had done up till then but the rest was fine it was a minor mistake and it works brilliantly. One of my favourite modules a single voice in my book. Hope the next board brings you success. I think everyone here has made some howlers of mistakes along the way so dont beat yourself up or loose heart. I trashed my first attempt at clouds by trying to hand solder the mcu without a microscope. I have a microscope now and its all okay now!

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cnicht
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Re: Plaits DIY

Post by cnicht » Thu Jun 25, 2020 12:40 pm

It does take a little working out as to what components are placed where but text orientation and proximity are a good guide.

It’s also a good final check with a continuity meter the pad connectivity.

artparks
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Re: Plaits DIY

Post by artparks » Thu Jul 02, 2020 4:29 pm

artparks wrote:
Thu Jun 25, 2020 10:49 am
Argh, trashed the board trying to desolder the DAC. New PCB ordered, fingers crossed I don't destroy this one.
Success - it was a fried/broken DAC, all working 100% now. Thanks for the help!

Now, up next my broken Clouds build, haha! Need to do a bit more digging myself on that one first.

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