MB808 PCB

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piccl
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MB808 PCB

Post by piccl » Tue Sep 22, 2015 8:29 am

After searching the forums for updates on this project, I stumbled across what appears to be the Eagle files. They have been around for a couple of years, so somebody must know about them.

http://www.subatomicglue.com/808l0g/bui ... %20boards/

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Post by Jarno » Tue Sep 22, 2015 9:20 am

Pretty good, these are the files that Moogah did, and which somebody else took over (not to a very high degree of success, see Dougster debacle).

By no means finished projects, but you can start from the schematic in eagle, it will save time since the schematic is already done. Problem some work on triggers and accents is needed to get this into separate modules. For some reason they have pulled it apart into the separate sections.

Good find!

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Post by Altitude909 » Tue Sep 22, 2015 9:51 am

Those are the individual voice parts from rev 1. They were made for debugging purposes and are far from complete. I really think you're barking up the wrong tree here, all the documentation for the MB808 is permanently destroyed so you would be on your own starting this from scratch. Just get the Yocto and be done with it, I have both and the yocto is just as good.

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Post by piccl » Tue Sep 22, 2015 10:01 am

xpmtl wrote:Sight, this project is a mess :eek:

So i've researched a bit in all the infos available...

1. Eight-o-Eight.org schematics are not complete (lacks instrument encoder pinout, discrepancies between schematic SRs denominators and SRs pinout sheet) ^^
2. Original Firmware (on ucapps) requires 6 Shift Registers for DIns so it won't work with Doug's schematics.... (V3 has 5 SRs)

Conclusion : Either i use 6 SRs and i make new schematic or we'd need to compile a new firmware.

Problem : Don't know if I can do that :) i'm on mac, have to see if i can use Parallels to run MLab and compile and make the Hex file needed. Needless to say I have zero experience in that domain :mrgreen:


Sneak-Thief, some questions :
- I presume your version is equivalent to Doug's V2 (batch 2?) PCB? Does your's use original FW and do you still have schematics for Dins and Douts?
- Would the Accent circuit need to be on the sequencer part or on the voices part. It requires +15V and i'd rather avoid to have a +15v regulator on the sequencer pcb as all the sequencer needs is +5V
- Can you confirm that the Instruments Encoder is tied to D6 & D7 on Shift register #1
- Thanks

More later

EDIT : Kanji might have used original firmware. Reading his post on midibox forum, he says he used the second pdf that he posted which i think corresponds to the original FW.
https://www.muffwiggler.com/forum/viewt ... ?p=1335452

I also came across this. I am not sure if he was referring to the same schematics. I will PM xpmtl later to find if he knows anything about these.

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Post by BugBrand » Tue Sep 22, 2015 10:29 am

I've been chatting a bit with Piccl about this 'cos I took on someone's 'nearly' (ha) done MB808 a few years back..

I was passed the same files, but had only had a cursory look at them before.
Noted that they were quite messy/chaotic - getting your head around it all would take some time!

Yesterday I had a quick check -> could I 'combine' the individual .brd files (they all appeared to have the same outline/overlay) - it seemed to be going well, but.. some bits are def. not right or there are discrepancies or I made a boo-boo. (didn't try combing the schems..). And the resulting composite board file behaves very unwieldy - doing the ratsnest gives super slow 'calculating polygons' and there are a few air-wires.

Today did a quick comparison with the MB808 board I have - there's some kludges to the board (which maybe were documented on the old forum).

I had a look at the DIN/DOUT midibox bits a little - again, schems are messy and maybe have errors..

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Post by BugBrand » Tue Sep 22, 2015 10:33 am

Altitude909 wrote: Just get the Yocto and be done with it, I have both and the yocto is just as good.
But isn't the Midibox808 sequencer a lot more powerful? It seems to be pretty darn amazing/deep.

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Post by Jarno » Tue Sep 22, 2015 10:49 am

Not straying to far from eurorack myself, so individual modules would definitely my use for the files.

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Post by piccl » Tue Sep 22, 2015 11:28 am

Altitude909 wrote:Those are the individual voice parts from rev 1. They were made for debugging purposes and are far from complete.
It looks like there are files for the core, D-in, D-out and PSU. It might not be complete but definitely not just the voice parts. Is Moogah still around? Or did he disappear too.
BugBrand wrote:
Altitude909 wrote: Just get the Yocto and be done with it, I have both and the yocto is just as good.
But isn't the Midibox808 sequencer a lot more powerful? It seems to be pretty darn amazing/deep.
I agree. The yocto sequencer seems boring. And it isn't open source either.

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Post by BugBrand » Tue Sep 22, 2015 11:38 am

This is what the composite of the .brd files looks like..
So, yes, it contains everything, but it is an unusable mess.. (even if there weren't the errors, what the fff is up with the pots etc not being lined up?!)
Oh, also noted that the board I have has footprints on the PCB in the area mid-to-top right (not sure what these are for though..)
Image

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Post by Altitude909 » Tue Sep 22, 2015 1:28 pm

MB808 has too many button combos and it's hard to use without a screen. MBseq is great but it's easy to get lost in the interface with just buttons

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Post by piccl » Tue Sep 22, 2015 11:33 pm

BugBrand wrote:This is what the composite of the .brd files looks like..
So, yes, it contains everything, but it is an unusable mess.. (even if there weren't the errors, what the fff is up with the pots etc not being lined up?!)
Oh, also noted that the board I have has footprints on the PCB in the area mid-to-top right (not sure what these are for though..)
That's great you put them all together. It seems possible that this might work after some adjustments. Do you which member here might know more about this? I would really like a have a couple boards printed.

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Post by jarvis » Tue Sep 22, 2015 11:43 pm

BugBrand wrote:This is what the composite of the .brd files looks like..
So, yes, it contains everything, but it is an unusable mess.. (even if there weren't the errors, what the fff is up with the pots etc not being lined up?!)
Oh, also noted that the board I have has footprints on the PCB in the area mid-to-top right (not sure what these are for though..)
I don't recall what the footprints were originally for but I used them as alternative locations for the accent and master volume knobs.

it looks like your composite is missing the mixer and power supply?

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Post by piccl » Wed Sep 23, 2015 12:29 am

Is that the psu in the mid-to-bottom left? Where the toroidal transformer connects, or is it incomplete?

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Post by Jarno » Wed Sep 23, 2015 2:44 am

BugBrand wrote:This is what the composite of the .brd files looks like..
So, yes, it contains everything, but it is an unusable mess.. (even if there weren't the errors, what the fff is up with the pots etc not being lined up?!)
Oh, also noted that the board I have has footprints on the PCB in the area mid-to-top right (not sure what these are for though..)
Image
Agreed, you'd need to start over, too many opportunities for errors, and with boards that size, errors in PCB's are costly.

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Post by BugBrand » Wed Sep 23, 2015 5:26 am

Yes, 'PSU' section is on the composite board image - slightly down from mid-right. This takes transformer input to generate +/-15V rails and +5V rail.

'output mixer' is missing from the composite - you can see the small traces that should join to this, top-right. On my board these go to summing resistors, then a dual opamp mixer (not examined it)

Here are some board shots in case anyone is interested - top & bottom.. (9 pics, attached as zip)
[I did not build this board - just took it on.]
You do not have the required permissions to view the files attached to this post.

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Post by Altitude909 » Wed Sep 23, 2015 5:46 am

I dont suppose you have any of the documentation? I need the fix for the crash where the dual pot was wired incorrectly, I have a very short decay on mine

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Post by BugBrand » Wed Sep 23, 2015 5:53 am

I don't have details of kludges, no, sorry.. (guess there was lots of 8oh8 forum posts which got lost.)

Just checked my board and there are no kludges around the dual pot for the cymbal (decay) so..
What is the problem? I didn't notice any problem when I had a play, but didn't check that in particular detail.

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Post by Luka » Wed Sep 23, 2015 6:30 am

bugs (formally my) board was a v2 edition and the kludges were documented on the forum (except the messy psu kludges). sorry i don't have those files unfortunately. from memory there were some isolated ground planes and some misrouted traces in the sequencer section.

moogah used to be on the muff - he might have more info

the drum machine is really capable but would be hard to use with no lcd.

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Post by Altitude909 » Wed Sep 23, 2015 7:06 am

BugBrand wrote:I don't have details of kludges, no, sorry.. (guess there was lots of 8oh8 forum posts which got lost.)

Just checked my board and there are no kludges around the dual pot for the cymbal (decay) so..
What is the problem? I didn't notice any problem when I had a play, but didn't check that in particular detail.
The decay is too short compared to the 808, the fix was a jumper wire between the taps but but that's all that I remember (possibly a resistor swap as well). I'm not going to hump Jeff's leg over it since he washed his hands of this when he passed it to Doug. It's not a big deal but I'd like to fix it.

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Post by piccl » Wed Sep 23, 2015 12:04 pm

Bug by looking at your board and comparing it to the composite they look to be quite similar. It's too bad the composite is missing the mixer I was getting kind of excited.

I have found images of the mixer doug had for v3. I wish I understood electrical engineering more so I could get this to work. I wonder if I asked EE university student, if they would be able to help me.



Last edited by piccl on Wed Sep 30, 2015 12:23 pm, edited 1 time in total.

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Post by mOBiTh » Wed Sep 23, 2015 4:09 pm

The Yocto source code *is* open source and I'm definitely going to be adding to it (when I have time...)

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Post by piccl » Tue Sep 29, 2015 2:05 am

A quick update if anyone is interested.

I actually managed to contact Moogah. He gave me his email address and said that he would be happy to help. I have sent him several emails now, but I haven't received a response.

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Post by ganchan » Wed Dec 23, 2015 9:24 am

piccl wrote:A quick update if anyone is interested.

I actually managed to contact Moogah. He gave me his email address and said that he would be happy to help. I have sent him several emails now, but I haven't received a response.
I've reworked the entire project based on some infos, i've checked the schematics with the original one but they need more controls.
Quite all parts are palced on the board mimating the last Doug release that i liked more in the sequencer part.

https://www.dropbox.com/s/qpkjvw54dneec ... 7.png?dl=0

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Post by jarvis » Wed Dec 23, 2015 10:58 am

Looks great, ganchan! I'm interested to see how that works out for you.

And the pots line up! It's the little things... :hihi:

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Post by Barcode » Wed Dec 23, 2015 11:18 am

Really nice ganchan. Do you plan on adding a LCD to your board?

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