new project: small home recording console
- Thread starter Dimitree
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Dimitree
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so almost two months later, I started laying out the PCB for the input channels.
I'm using SMD resistors and ICs, but through hole (bipolar) electrolytic caps, and potentiometers and switches are PCB mount too.
I used a 20 pins Micro-Match connector with flat cable that will go to the jack PCB and will carry all the balanced signals for that channel (line input, daw input, balanced send and return, direct out).
I still haven't decided what connector to use for the fader, probably just a couple of shielded wires.
This is a preview of a single channel PCB (front and back layers), and once completed, the design will be duplicated multiple times on the same PCB (a single PCB will cover multiple channels, probably 4 channels or maybe up to 8 channels).
For the summing buses, I'm running perpendicular traces along the PCB, instead of using a flat cable like many larger consoles do.
Between every bus, there is a ground pour separating each other. I believe it could improve crosstalk?
Actually all the board is filled with a ground pour on both sides, and connected with many vias everywhere there is space for them.
This is more or less what I mean to do (the buses are highlighted in orange)
View attachment Untitled-1.png
This is a Photoshop preview of how I imagined the front panel (200mm * 31mm).
I haven't labeled the front panel yet, but essentially it is like this: trim (+/-10dB) potentiometer, insert ON-OFF switch, line/daw input selector switch, 3x AUXes with pre-post fader switch, PFL button (yellow), 4 routing bus buttons, pan potentiometer, SIP and CUT buttons.
I hope it will not turn out to be a disaster
I'm using SMD resistors and ICs, but through hole (bipolar) electrolytic caps, and potentiometers and switches are PCB mount too.
I used a 20 pins Micro-Match connector with flat cable that will go to the jack PCB and will carry all the balanced signals for that channel (line input, daw input, balanced send and return, direct out).
I still haven't decided what connector to use for the fader, probably just a couple of shielded wires.
This is a preview of a single channel PCB (front and back layers), and once completed, the design will be duplicated multiple times on the same PCB (a single PCB will cover multiple channels, probably 4 channels or maybe up to 8 channels).
For the summing buses, I'm running perpendicular traces along the PCB, instead of using a flat cable like many larger consoles do.
Between every bus, there is a ground pour separating each other. I believe it could improve crosstalk?
Actually all the board is filled with a ground pour on both sides, and connected with many vias everywhere there is space for them.
This is more or less what I mean to do (the buses are highlighted in orange)
View attachment Untitled-1.png
This is a Photoshop preview of how I imagined the front panel (200mm * 31mm).
I haven't labeled the front panel yet, but essentially it is like this: trim (+/-10dB) potentiometer, insert ON-OFF switch, line/daw input selector switch, 3x AUXes with pre-post fader switch, PFL button (yellow), 4 routing bus buttons, pan potentiometer, SIP and CUT buttons.
I hope it will not turn out to be a disaster
MidnightArrakis
Well-known member
>> You want to avoid -- entering/exiting -- a pad with angled-routing such as this:This is more or less what I mean to do (the buses are highlighted in orange)
I hope it will not turn out to be a disaster
-----------------↑↑↑--------
These are known as "Acid Traps" during the PCB-fabrication process and can create issues with your finished board later on down-the-road.
I have a $4,200 "GERBER & N/C Drill" analyzing and editing program that I run all of my GERBER and N/C Drill data files through before I send my files out for fabrication. Should you send me the GERBER and N/C Drill files of your PCB's, I will process them for you and let you know what issues it finds and reports. This program will find "Isolated Copper", "Invalid Annular Ring", "Insufficient Soldermask", "Silkscreen Over Pad" and several other PCB-fabrication issues. It's always better to be "Safe, Than Sorry"!!!
Another forum member had sent me their GERBER and N/C Drill files of a PCB of theirs asking me to -- fix -- a couple of items for them. However, they were -- shocked -- when I told them that my program had found at least 7 other issues with their files that they were completely and totally unaware of!!! I went through their files and fixed everything for them. They then had 100 PCB's fabricated from the > NEW < GERBER and N/C Drill files that I had generated after my repairs. This member then wrote back to me to let me know that their new batch of PCB's were the -- BEST LOOKING -- PCB's that they had ever had made!!! And.....they were made by the same fabricator they had always used before!!!
Just sayin'.....
/
warpie
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MidnightArrakis, would you like to share the name of the program with us?
With all the boards having active heat producing parts component side down and no ventilation could lead to heat buildup and failures - capacitor life reduces exponentially with increase in operating temperature. Vertical board orientation allows for airflow between channel boards whereas it seems you are envisaging a flat plane which may need fan assisted cooling.
Dimitree
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Thank you, will fix those right now!
Thanks, I didn’t consider this aspect, I will study the matter.
Another consideration is the replacement of failed components when using SMD (also the actual build) - for such a low populated board I’d be considering through hole especially for IC’s where socketed chips make for easy replacement when they fail. I service a lot of audio gear and multi-pin IC’s in surface mount format require a bit of work to remove and especially to solder the replacement back onto the board without solder bridging - resistors and capacitors are also very small and fiddly to refit.
Dimitree
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- Joined
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thanks for those tips, I actually don't fear replacing ICs in SMD format, I'm use to the removing and replacing of even smaller formats like those used by many microcontrollers, it becomes really fast and easy when you get used to it
Socketed IC’s make for minimum downtime 
MidnightArrakis
Well-known member
[would you like to share the name of the program] -- May your clicking on the link below "set you free"!!!
https://www.downstreamtech.com/products/cam350/
[with us?] -- Who or what is "us"?
/
MidnightArrakis
Well-known member
>> I found a few potential "disasters":so almost two months later, I started laying out the PCB for the input channels.
View attachment 124134
I hope it will not turn out to be a disaster
-- OOPS!!! --
Well.....the "blue on blue" makes it next
to impossible to see, but if you look at
this closely enough, you have another
"acute angle" bit of routing here:
------------------↓↓↓---------------------
>> Where does this route go???
>> And.....where does this route go???
>> Do these little "isolated copper islands" actually
connect to anything? Without being able to see the
composite-image of both of the GERBER-file routing-layers
together to see if these pads are connected on the
"other side", these -- could be -- just "isolated copper
islands". My CAM350 program can detect if these are
connected or if they are isolated!!!--------↓↓↓↓↓----------
------------------------------------------------↑↑↑↑↑↑↑↑-------------
>> Another -- possible -- "isolated copper island" area:
>> Going back to my comment in Post #54, if you would want to send me either your Eagle schematic & PCB-design files so I can import them into my CADENCE/OrCAD "PCB Editor" program, I will give your layout a "once over" to see if I can find any other obvious issues. Then, by importing your GERBER and N/C Drill data files into my CAM350 program, I can then check for a whole separate set of "fabrication" issues, which are of course, different than what the layout issues would be. I'm here to help.....................................................................................................................................only if you want it!!!
/
Last edited:
MidnightArrakis
Well-known member
>> Try designing a PCB that is only 1.25" square (31.75mm square) that had about -- 205 -- "0201-size" Surface-Mount capacitors and resistors on -- BOTH SIDES -- of the 0.032" thick (0.813mm thick) laminate, that not only had a 256-Pin micro-BGA that required using 4-mil tracks and spacing, but also needed 8-layers with multiple split "Power & Ground" layers!!! This PCB was for a Department of Homeland Security "covert intelligence-gathering and surveillance" project!!!
TALK ABOUT "VERY SMALL AND FIDDLY"!!!.....
/
warpie
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ruffrecords
Well-known member
The want a helluva lot of information just so you can download a demo. Not a good way to win business.
Cheers
Ian
I would hope you will do component numbering/marking on the PCB to enable servicing later on down the track. Yamaha for example label everything with clever ways of bracketing rows of components in very small layouts. Even when you’ve designed and built something yourself you will forget what went where.
MidnightArrakis
Well-known member
The number of members on this forum who design PCBs with their REF DES indicators (C3, R8, IC5, etc.) placed within the component silkscreen, so they are "hidden" after you place a component over it, astonishes me!!! How does THAT even make any sense??? It is no wonder -- WHY -- aliens have never landed here. They have concluded that THERE ARE NO INTELLIGENT LIFE FORMS HERE!!!
/
ruffrecords
Well-known member
As often as not I do not have a ref des on the silk screen at all. When populating a board I do not want to have to look at the ref des on the board then look up the value on schematic/BOM, then get the part and fit it. Instead I write the component value on the silk screen. I just read the silk screen, get the part and stick it in. Very handy when you have several parts with the same value as you can easily fit them in one go.
It is worth remembering that DIY is not the same as volume manufacturing.
Cheers
Ian
MidnightArrakis
Well-known member
While I certainly do understand what it is that you explained about how you populate your PCB's, that is a completely different and separate issue than the one I was griping about in my comment. Once you cover-up a REF DES with a component part and a few hours or a few months later when you need to find "R8" on your board, you can't because the actual part is covering the REF DES silkscreen.
However, by placing the component values in silkscreen instead of a REF DES and you have 8 separate 10K resistors in your circuit that you are needing to troubleshoot, I am certain that trying to locate a specific 10K resistor becomes more difficult simply because there is no REF DES to reference. But.....maybe that's just me!!! Dunno.....
One aspect that I have noticed by being on this forum when it comes to designing and building electronic equipment for your own personal use is that.....whether I am designing a new product for a defense contractor or a medical electronics firm or for myself here-at-home.....I do everything for everybody the same way, whether it is sheet-metal chassis designs and/or the PCB-designs. In other words, how I design something for myself is how I would design something for a defense contractor. I don't know how to do things any differently.
>> In "other" news.....I'm putting in the finishing touches and creating the final "Fabrication Drawings". Upon doing a close scrutiny of my "final" designs, I came across a couple of "hidden" errors, but I now have everything worked out. All CAD-design files and PDF fabrication files will be e-mailed shortly. Hang-on!!!
/
MidnightArrakis
Well-known member
>> I sent their Sales Dept. a message to let them know that. I will let you know if they respond back to me.
When tracking faults on a board and referring to a schematic which usually also has the value next to the component ID# it makes it easier for service to have the ref des on the board. Some manufacturers in their service manual parts lists also have the board drawing number or schematic page and a location grid reference - eg. P9 A7. In some of the manuals I use they have active links for things like cable connections to take you to the next diagram directly by clicking on the connector end with the mouse, components like listed IC’s when you click on them that takes you to the locations that these are used in the schematics.
