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hatmoose

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The case is coming along nicely, I printed the initial prototype to make sure all the holes were aligned (spoiler, they werent).

Then fixed it up for mechanical strength so now the top and bottom look like this.
revised bottom.pngREVISED TOP.png

And after printing it looks like this.
IMG_7302.jpegIMG_7295.jpegIMG_7303.jpeg

The bottom bit is a tub for component leg clearance, the board sits on 4 extruded pegs that align with the holes for the bolts. The top bit clamps down with 4 x M3 20MM cuphead bolts and the board is held in place by 4 pegs extruded from the bottom that also align with the holes for the bolts.

The mechanical stress relief on the BNC and SCART connectors was already good so I didnt worry too much about that. The mechanical stress relief on the RCA jacks was very poor so I put a hole at the top for an M3 bolt or screw (any length is fine).

Now that I have a "complete" project case I can do a quick design study on how to attach it to various PVM's and BVM's. Not ruling out velcro at this stage, but something a little more sophisticated would be nice...

IMG_7301.jpegIMG_7300.jpegIMG_7299.jpeg
 

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hatmoose

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The design study for the "universal" mounting bracket started out really well, then I got a sore back from moving PVM/BVM's, got to about half of them and stopped - The mounting bracket will be "universal-ish"

IMG_7310.jpeg

In all cases I wasnted to keep the co-ax cables to 1 foot or shorter, this could be tighter with right angle BNC connectors, but i didnt have any right angle BNC crimp plug, and right angle BNC couplers are an unnecessary connection. So I stuch with the standard ones

Also in all cases I wanted this to be non-destructive - would be super simple to just drill some 3mm holes and use panel screws, but this needs to be 100% reversable without damage. Shoud work with zip-ties, 8mm M3 button head bolts (for metal) and 12mm M3 button head bolts (for plastic)

Tonnes of good mounting options on BVM's - the cases are all metal and all modular (this is a BVM-1416 and a BVM-E1U)
IMG_7315.jpegIMG_7312.jpeg

The PVM's were a bit tricker - I'm not really a fan of using the plastic parts of the case for mechanical strain relief but for the 14" and 20" PVM's there is no other option but (thick) placstic for back-mounting, side and top mounting can go into metal. The PVM 8/9 series were the hardest because the back panel is really crowded (this is a PVM-8040, PVM-9L2, PVM-14M2, PVM-20M4, PVM-2054)

IMG_7328.jpegIMG_7325.jpegIMG_7330.jpeg

After a few hours of measuring and placing this was the result.
bottom bracket.png

I'll get this printed up, do some test fittings, and call it "done"
 

hatmoose

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TL;DR none whatsoever - mechanically competent RG59 co-ax cable perfoms exactly the same regardless how beautiful your crimp tool is, especially when it's only a few feet long

This was my test rig for the BNC cables. HP54600A, Sega Dreamcast with GDemu clone rnning 204p test suite, CHeap dreamcast SCART cable, Voultar SCART to RGBS adaptor, Sony PVM9L2 w/129x clone card (the close card is what kicked this whole thing off in the first place)
IMG_7382.jpeg

I'm loving the hell out of the HP54600A scope - I bought it for quite a lot of money off a local auction site (because everyhing in NZ costs quite a lot of money). I came with a bunch of sophisticated and expensive PC interface "stuff" and test automation "stuff" that i have never learned to use - as you can see from these photos it is probably time :) It was "cheap" (by NZ standards) because the CRT had failed. Luckily I happen to be quite good with CRT's, now works perfectly.

However I'm starting to butt up against the the limits of what it can do now - 4 channels would be amazing, it only does 20msa/s so it's really only good up to 20mhz (despite being advertised as 100mhz), and the volts/div go from 20ms all the way to 50ms with nothing in the middle, and the onboard memory is 4k. For what I'm currently doing it's awesome, and I love the HP software, but I can see the end of the road...

Ideally I want the same software, but with more capable hardware - if anyone has a HP54602B, HP54624A or the like selling cheap in NZ I would love to know :)

Anyhoo, for this test I was using the plain color screens and the plain white screens out of 240p test suite because I know how those are susposed to look on a scope. On a plain white screen all three color chanels should look like this
IMG_7388.jpeg

Anaalogue video is low enough bandwidth that I could store the signal and zoom in all the way in on that rising edge. There is absolutely no diference whatsoever between a 1 foot BNC cable crimped with a $400 criming set and a $20 criming set. But it was fun testing
IMG_7427.jpegIMG_7426.jpegIMG_7412.jpegIMG_7430.jpeg

Since I had all the testing gear set up I also had a look at the diffeence between heavily shielded RG59 cable with BNC connectors, and rubbish cheap audio cable with RCA connectors. this was actually quite interesting

There is a tiny tick at the top of the rising edge, this is basically when the line is drawn, the gun is off, the retrace is done and the gun needs to go on again to draw the next line. Here it is in "normal" scale, and zoomed in a bit on that leading edge
Chanel 1 (top) is standard RCA cable
Channel 2 (bottol) is RG59 co-ax cable
You can probably already see the problem
IMG_7388.jpegIMG_7385.jpeg

Here it is zoomed in (a lot) more - I had to put the co-ax cable at the top and the RCA cable at the bottom on these screens to fit it all in. As you can see the cheap RCA cables mangle the "tick" at the top of the leading edge. Ideally this would be a straight up spike, but in analogue electronics such a thing is not possible.
IMG_7403.jpegIMG_7403.jpeg

Shielded co-ax comes up sharply to energise, then drops to "on" and stays there. It's not a perfect spike, but it's close. So the signaling voltage is done by the time the gun starts drawing the beam on the phosphor
Unshielded RCA comes up but not that sharply, then drops, then comes back up again, then drops again to "on". It's nothing like a spike, it's more like a wobble. The signaling voltage that gets to the monitor is all over the show.

I was actually realy pleased that the scope let me "see" the snake oil that those cable sellers have been peddling for years. Does it make a difference to image quality? Probably none at all, but it is actually a really thing, and you actually can see it if you look for it.
 

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hatmoose

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Did some more work on the cases today.

Unfortunately I have not yet broken my unfortunate addiction to sketchup, so all the models throw up errors in Cura.

Anyhoo, I wanted to round off the corner of the cases to male them feel a bit more human. How to do this? With the plugin named "RoundCorner" of course!
https://sketchucation.com/plugin/1173-roundcorner

I also put the Voultar RGBS logo on the top, and "PCB by Voultar" on the bottom to recognise his work. Voultar - if you ever read this thank you very much! What you do is valued and appreciated. There is actually a really cool RGBS easter egg on the board itself, I saw it and the artistry made me happy, thankyou...

Top and bottom now look like this - if you let the slicer generate supports it messes up the lettering, but if you dont generate supports it messes up the holes (too many hanging intricate edges) What to do?
I drew my own supports for the screw holes in the top of the case - they are "hanging" not attached to anything, but should provide the structure needed to print the complex intersection of the lettering and the screw holes

This is how they look, printing now
RGBS final.pngFinal bottom.png
 

hatmoose

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This was a good example of how the picture in the CAD software is not the product in the real world.

I wanted the Voultar "RGBS" logo across the top of the case, and I wanted the screw holes to line up with the screw holes in the PCB. This meant that the letters and the holes occupied the same space

FDM 3D printers have big problems with this kind of shape - they can print things cut into a surface really nicely in both X and Y, but they can only print one surface cut into another surface in Y. Because the Filament is Deposited it can only stick if there is something underneath. Makes perfect sense when you watch how the printer actually works, but easy to forget in the CAD program.

This is how it looked in CAD - very nice!
nocuf.png

This is how it looks in real life. The top holes that intersect with the letters and are set back off the surface look like a dogs breakfast
IMG_7472.jpegIMG_7470.jpeg
If this was a resin printer this would not be a problem, but I dont have a resin printer...

The solution is to draw a "cuff" around the top of the hole to give the the filament something to stick to. I guess I could have made this .1mm wide and manually picked it out afterwards, but I really wanted to get the tool to do the whole job - so I drew a cuff like this.
cuff.png

So the finished case looks like this - again it is clear that I'm no product photographer :) I really like the color of this filament, it's CPS2 blue. But it doesnt melt at quite the same temp as my other filaments
I printed this this at 60/195, 20% infill, .16mm layer height, no supports
IMG_7481.jpegIMG_7478.jpegIMG_7479.jpegIMG_7480.jpeg
This time it really is done, no more changes.

Getting nuts and bolts that are "dimensionally accurate" out of china is a massive pain. Also there is no QC and no lot number, no batch number, no serial number. So just because they have been good the last 10 times does not mean they are going to be good the 11th time. Ali at your own risk

BOM to assemble the case is
4 x M3 20mm cup head bolts - these have to be 20mm in order to engage the nut fully but not stick out the top or bottom of the case
https://www.aliexpress.com/item/4000784829771.html
4 x M3 nuts (5.5mm in diameter face to face, 2.5mm high)
https://www.aliexpress.com/item/4000602853448.html
1 x M3 10mm button head bolt
https://www.aliexpress.com/item/4000038065691.html
 

hatmoose

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I realised that I hadnt done any work on the full sized cards for a while - these seem to be Martins perfered versions - they are feature complete now. Awesome!

BKM-129x SCART-VGA edition is here https://github.com/skumlos/bkm-129x-scart-vga - with contributions from our very own @bodgit !!!!!!
BKA-129x full sized edition is here https://github.com/skumlos/bkm-129x-simple-full
I've already written about the "small" board above. Will start work on the full sized ones

I got the small board done in red, the VGA in yellow, and the full size done in green to keep it simple.

I'm particuarly interested in the "VGA" board as it allows you to use the 480p PVM's (20L5 and 14L5) as VGA monitors. I dont have an L5, but several of my friends do - I'm sure they will love this idea. And having a SCART port in my PVM will be one less connection needed. The Full sized card has outputs as well as inputs - I often use my L9 as a kind of crash test dummy to make sure that rotten video signals are not going to destroy one of my "good" PVM's - having the passthrough will allow me to have them all hooked up at the same time. Lots of fun use cases with these guys.
IMG_7738.jpegIMG_7739.jpeg

The BOM is written on the card, from that I've generated this orderable BOM with options from Mouser and Digikey - the global component shortage is biting hard, have noted where stock is hard to get

CSV for both is attached - Both Mouser and Digikey will process this into a cart without too much fuss

This is the VGA/SCART BOM
1632103493566.png


And this is the Full sized clone BOM
1632103554861.png
 

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hatmoose

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Edit: Ooops, nearly forgot the VGA, SCART and backplane connectors - I couldn't find these on either Mouser or Digikey. So you pays your money and you takes your chances with Aliexpress. These are all just bent pins in plastic shells, surely even Ali cant screw this up, right... right?

VGA/SCART version
J1 - this is the (female) VGA connector - the spacing to the edge of the board is a bit funky, Way longer than I've seen on any other VGA connector. This one should do it
https://www.aliexpress.com/item/4000075603010.html
J2 - this is the (female) SCART connector - The ones that clip to the PCB are quite hard to find at the moment..
https://www.aliexpress.com/item/4000771556293.html
J5 - this is the backplane connector
https://www.aliexpress.com/item/4000113049761.html

Full sized clone version
J1, J11, J2, J21, J3, J31, J4, J41 - BNC connectors
https://www.aliexpress.com/item/32888289661.html
J5 - this is the backplane connector
https://www.aliexpress.com/item/4000113049761.html
 

bodgit

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Edit: Ooops, nearly forgot the VGA, SCART and backplane connectors - I couldn't find these on either Mouser or Digikey. So you pays your money and you takes your chances with Aliexpress. These are all just bent pins in plastic shells, surely even Ali cant screw this up, right... right?

VGA/SCART version
J1 - this is the (female) VGA connector - the spacing to the edge of the board is a bit funky, Way longer than I've seen on any other VGA connector. This one should do it
https://www.aliexpress.com/item/4000075603010.html
This is the VGA connector I used from Mouser: https://www.mouser.co.uk/ProductDetail/806-K66X-E15S-NJVESA

It sits flush against the edge of the PCB. I notice it is now out of stock, but the model number might be useful to find it elsewhere.
 

bodgit

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I finally managed to finish off and test my two BKM-129X cards, (needed to wait for the ADG1611 chips from China, Mouser shows those unavailable until November 2022!). I built both the SCART & VGA version as well as the full BNC clone. The former is great for the input support, the latter is handy so I can use the passthrough to chain in my Oscilloscope and use external BNC terminators.

You can spot the deliberate solder bridge on the BNC version to apply the missing low pass filter fix on the THS7374, should I ever be in a position to test 720p:

IMG_2898.jpg

IMG_2899.jpg


My little 9L3 PVM now has RGB:

IMG_2902.jpg


All that I need now are some 3D printed brackets to keep the cards secure in the PVM; there's a decent enough BNC version that Martin created, but I could do with one for the SCART & VGA version. I found one but it looks like its for an older revision of the PCB so it might need tweaking.
 

hatmoose

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Just came here to say that I am super-jealous of your sweet, sweel L3 and its 450TVL
My L2 has a mere 250TVL and I miss those extra lines every time I look at it :)

Edit: Whoops, also, do you have part numbers for the push switches and the audio connector on the VGA version please?
Edit: Edit - never mind, found it (written right on the PCB)
 
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