DIY: 4ms RCD

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Post by dude » Mon May 30, 2011 12:48 pm

ack. thanks for checking! 4ms, are there any simple resistor value changes which would/could cut the 12v gates to 5v ish?

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Post by dude » Mon May 30, 2011 12:49 pm

or would it be coding in this case?

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Post by urbanscallywag » Mon May 30, 2011 1:43 pm

definitely not coding. i would probably just do a resistor divide. maybe 4ms can comment
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Post by dude » Mon May 30, 2011 6:17 pm

sduck wrote:
dude wrote: i have a plan for an evil 5u scm/rcd freak panel. they both run on 15 volts right?
Me too! And yes, according to 4ms it'll all run on 15v also. I'm thinking it'll all fit behind a 2U motm size panel, although there may be some squeezing to make it fit.
any chance you could share a fpd file if you arrive at something you like?

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Post by DGTom » Mon May 30, 2011 8:15 pm

RCD works great on 15V here.

@dude

why do you need to drop the pulse voltage so much? Better to have any modules that can't handle over voltage protected than "cripple" a module & run the risk of having to boost mid-patch,

depends on the application I guess

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Post by dude » Mon May 30, 2011 8:20 pm

modcan is why. i am in the land of white where trigs are 5v and thresholds are tickled with the greatest of ease :hihi: 12v is just way too hot for me. it wouldn't be a crippling at all. i am a stickler for voltage range assimilation. it is fetishistic at this point.

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Post by DGTom » Mon May 30, 2011 8:31 pm

fair enough, so _every_ digital out on a Modcan is 5V? :eek:

what a strange & alien landscape :hihi:

this guy;

http://www.raltron.com/cust/tools/voltage_divider.asp

might help, I'd measure the outputs on your supply tho,
just to ensure maximum assimilation.

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Post by dude » Mon May 30, 2011 8:47 pm

yeah, 5v for most everything. even my slope detector seems to put out 5v gates. i live in a 5v bubble and i dig it. all (or almost all)the modulation ins respond fully to 5v so that part is perfect but also, the smaller voltage range helps to scale odd things to use them for 1v/o pitch info. it doesn't make sense for people that use all sorts of different systems, but for 1 system it is amazing. i absolutely love that about modcan. it is one of those things that helped me drop all other formats (aside from diy). when a system gets standardized in that way, a level of freedom is felt, at least for me, that was just not previously possible.

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Post by sduck » Mon May 30, 2011 10:11 pm

dude wrote:
sduck wrote:
dude wrote: i have a plan for an evil 5u scm/rcd freak panel. they both run on 15 volts right?
Me too! And yes, according to 4ms it'll all run on 15v also. I'm thinking it'll all fit behind a 2U motm size panel, although there may be some squeezing to make it fit.
any chance you could share a fpd file if you arrive at something you like?
Absolutely - but it's not in the immediate queue, so maybe you'll come up with something evil first?!?
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Post by dude » Mon May 30, 2011 10:39 pm

it sounds like neither of us working on it for a bit. if i get anything i will be in touch. have you ordered the boards/parts? i am thinking of getting all the kits the next time i come into some money, but that may be a while.

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Post by sduck » Mon May 30, 2011 10:52 pm

I just received the pcbs and chips in the mail. My plan is both the rcd and scm in the middle, with the breakout board components for each on either side. I think that'll all fit, although it's a few more jacks than normal. I need to find some small, especially annoying leds for this one. This project is behind the 258 vco clone, which is behind the motm 410 builds, which is behind some repairs, which is behind finishing this m185 sequencer, so it's some months down the road.
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Post by dude » Mon May 30, 2011 10:57 pm

cool, yeah that sounds like a perfect plan. i was also thinking of normalizing the scm /1 switch-jack style to the rcd konk in. if i remember correctly, the scm starts on its own but the rcd requires clock input. this way, they would always be going unless/until overridden by ext konks. should be simple right?

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Post by dude » Mon May 30, 2011 11:09 pm

also, what leds are you thinking? i am picturing really small 1.8mm diffused all in one color. they will have to be the small ones and be offset as there won't be any panel space where they might normally go in motm-grid land. clearly this won't be motm grid-able.

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Post by urbanscallywag » Mon May 30, 2011 11:20 pm

the multiple colors of the RCD LEDs are really cool :cloud:
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Post by sduck » Mon May 30, 2011 11:22 pm

Yes, some kind of normalization like you're saying would be the plan. And easily do-able. No idea on the leds yet. Probably some variety of 3mm ones. I think the kit comes with 3mm (?). And yes, not on the motm grid, although maybe the center line of jacks would be - dunno yet.
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Post by dude » Mon May 30, 2011 11:31 pm

ah, well if it comes with leds, then i will likely use those. motm grid center sounds good. the knobs of the scm bustout are what concern me. me hopes they be small!

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Post by Scaff » Fri Jun 10, 2011 1:07 pm

the postman rang today and after 2,5 hours soldering i finished the SCM with success. It was my first euro soldering project and it was nice and easy.... I want more :banana: The break out will follow tonight! :tu:
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Post by julianw » Mon May 13, 2013 6:30 am

Well I've built the SCM and RCD boards and expansion, just need the 5U panel and I may be able to shoehorn this into the modular.......

As an aside - you can do some really cool shuffly stuff with CGS burst generators they are a fairly easy build if you use the right rotary switch that solders into the PCB, although you can't use the Bridechamber panel with it.

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Re: DIY: 4ms RCD

Post by Whelm » Fri Mar 20, 2020 2:26 am

Alright DIY gurus. Deep necro on this one as I have yet again run into a problem I'm having trouble solving.

I recently built up an RCD to compliment my SCM+BO. I fucked up and installed 1k bussed arrays instead of isolated, so I had to rip those out and install the proper arrays.

Now the unit is working normally except there is no output or LED activity on the /1 jack (OUT1). All the other outputs function normally. This behaviour is consistent with all jumper combiniations I've tried.

4ms helpfully provided the schem when I reached out to them but since they don't seem to list it publicly I think I'd better not share.

However, I've gone over the circuit for output 1 several times. I can't find any shorts, I can trace continuity from ATMEGA pin 14 through the resistor arrays, the LED, and the transistor. The voltages on the LED and on pin 5 of the 3.9k array are correct. The LED and the transistor are oriented properly. I even reflashed the chip because why not.... ATMEGA pins are showing the proper voltages for +5 and GND.

But still there's no activity on Out1.

So I think maybe the LED is dead, might as well swap that out. Which I do. Now the result is that the LED for OUT1 is on constantly! Still no output on the jack, but the LED is on forever, and now reads around 3.3V instead of 5V... The rest of the outputs are still functioning normally.

Which... I mean... LED is anode in the square hole, just like all the other ones, just like the one I replaced. Did I get a weird batch of blue LEDs from Tayda? Or, as per usual, am I doing something dumb? If the LED wasn't the problem, why did changing the LED result in this slightly different but equivalent malfunction?

OUT1 reads 0.08V constantly regardless of input.

There doesn't seem to be many places where a problem could be, given that all the other outs are working. So presumably the problem is between pin 14 of the ATMEGA and the jack, but I can't find anything wrong there.

Thank you for your insights.
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Re: DIY: 4ms RCD

Post by Whelm » Sun Mar 22, 2020 1:51 am

Further investigation has revealed that pin 14 on the atmega, which corresponds with OUT1, is outputting 0.74V regardless of clock input. The pins corresponding with other outputs vary from 0-5V in accordance with their respective divisions.

Is this indicative of a microcontroller problem?

I flashed the atmega before realizing the problem with the wrong array type. Might I have caused some weird damage to the controller affecting pin 14?

There are so few components between the input and the atmega for anything to be going wrong with... and all the other divisions are functioning as expected.

Perhaps it is time to order a new microcontroller.

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Re: DIY: 4ms RCD

Post by sambell001 » Thu Mar 26, 2020 4:20 pm

Anybody got any idea what might be wrong with my RCD build if, when I feed it a clock, nought happens?
Although all the leds are lit up. :despair:

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Re: DIY: 4ms RCD

Post by BartBral » Thu Mar 26, 2020 5:44 pm

@Whelm,
Further investigation has revealed that pin 14 on the atmega, which corresponds with OUT1, is outputting 0.74V regardless of clock input. The pins corresponding with other outputs vary from 0-5V in accordance with their respective divisions.

Is this indicative of a microcontroller problem?
Remove the ATMEGA and check pin14. Is there still 0.74V on the pin?

I would check for shorts at the first two transistors. (near input and output1)
And check for shorts and cold solder joints at the resistor arrays.

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Re: DIY: 4ms RCD

Post by BartBral » Thu Mar 26, 2020 5:52 pm

@ sambell001,

Loads could be wrong! Hard to see from here.
Did you put in the ATMEGA the right way round? Did you put it in at all? ;)
Do you have the Bussed Resistor Arrays in the right way?

Please make some nice photos, that'll help narrowing down your problem.

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Re: DIY: 4ms RCD

Post by Whelm » Thu Mar 26, 2020 6:30 pm

BartBral wrote:
Thu Mar 26, 2020 5:44 pm
@Whelm,
Further investigation has revealed that pin 14 on the atmega, which corresponds with OUT1, is outputting 0.74V regardless of clock input. The pins corresponding with other outputs vary from 0-5V in accordance with their respective divisions.

Is this indicative of a microcontroller problem?
Remove the ATMEGA and check pin14. Is there still 0.74V on the pin?

I would check for shorts at the first two transistors. (near input and output1)
And check for shorts and cold solder joints at the resistor arrays.
So I've been emailing with Zach from 4ms who has been very helpful. He suggested shorting pins 14 and 13 (which corresponds to Out7). If there was a problem with the pathway from Out1, the expected result would be that there would be the /1 output on Out7. Instead the result is that Out7 behaves as normal, and Out1 mimics Out7.

This suggests that there is no problem with the Out1 pathway, since it is happy to take the output from pin 13. This seems a pretty strong confirmation that the atmega is the problem so I'm just going to order another one with my next Mouser order and see how that goes. Having the wrong arrays installed might have fucked up the IC somehow? Seems strange either way because all the other pins are behaving normally.
Last edited by Whelm on Thu Mar 26, 2020 6:34 pm, edited 2 times in total.

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Re: DIY: 4ms RCD

Post by Whelm » Thu Mar 26, 2020 6:31 pm

sambell001 wrote:
Thu Mar 26, 2020 4:20 pm
Anybody got any idea what might be wrong with my RCD build if, when I feed it a clock, nought happens?
Although all the leds are lit up. :despair:

Did you assemble from a kit or source your own parts?

I made the mistake of installing bussed 1k arrays instead of isolated, and that produced behaviour that sounds like what you're describing.

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