Open Source release of MiSTer Multisystem Console hardware all-in-one I/O design

[emiliom]

I remember changing something important that was included in the readme/documentation files somewhere in the github.

EDIT

I think it was the ENIG finish from the readme "Material to be 1.6mm FR4 4-layer PCB lead-free (RoHS compliant) with an Electroless Nickel Immersion (ENIG) finish.
Green solder resist on both sides including vias."

Yeah I saw that. The solder resist is fine. I chose blue, but I checked and there's no performance difference between colour, it's purely aesthetic.
The finish is my bad. I didn't see that it had to be ENIG finish.

But they are still saying to me those don't fix my problem, so I don't know what the issue is.

Just FYI, they ended up cancelling my order basically because I was asking too many questions. So I reordered again, exactly the same except I selected ENIG, and the second time it went through no problem. So even though they said it didn't make a difference, either it did, or someone just didn't know what they were doing the first time. Ah, well, at least it's gone though ok now.

[LeeW]

Would like to buy a MiSter Mulisystem but that doesn't seem like a possibility, so I thought I would have a go at having an assembled PCB made... But the provided BOM is terrible bordering on useless. I've spent a lot of time trying to decipher this and think I finally have a mostly complete parts list (but take this with a grain of salt as I really can't be sure, PCBWay also have no idea what most of the parts are either): https://pastebin.com/yS43Sz2w

One big problem is that most components seem to be low or no parts available, and while most parts should be easily changeable in terms of functionality, the pin positions and item sizes seem to be drastically different for replacement parts?

Absolutely no idea what J29 is. As mentioned the crystal seems like a challenge because they all look the same but have different electrical specs. The three LEDs next to the push button have different colours from videos I've seen, with the right hand LED (LED1) being green and the left hand LED (LED3) being orange/red, haven't seen the middle light come on in any videos. Not sure if the LEDs have any specific requirements.

To be honest I really have no idea what I'm doing with any of this stuff, really I would rather just buy one outright. However, if I can manage to figure this out it looks like it could be around £50 per assembled board?

[emiliom]

anyone having any luck with finding the parts?

Only the ones where the part codes are listed on the spreadsheet. The resistors and capacitors I've basically guessed at the specs.
The really tough things are the connectors and buttons. I've been trawling through pictures on component websites to try and match them but not a lot of luck, especially with the front push buttons and the vertical HDMI connectors. I'm waiting for my boards to arrive so that I can measure the pin distances and then maybe try and match things up by looking at the datasheets, but I think it's going to be a long job.

The other thing that's a real bugger is the 12MHz crystal. Great, I know it's a 12MHz crystal but without knowing the correct Load Capacitance and max ESR we're a bit stuffed. I spent a lot of time talking to ChatGPT about this - it's actually turned out to be useful for once! Seems that the most common LCs for a 12MHz crystal are 18pF & 20pF, so I'm thinking of buying a couple of each with different ESR values and seeing if they work out. I'm actually in touch with someone at Terminus who make the FE2.1 chip to try and find out what the LC and ESR values are (as the crystal connects to pins 22 and 23 on the chip), so if I get that info I'll post it here.

Problem is if there's more than one wrong component when it eventually gets put together, how you going to know which one/s is/are wrong?

Following on from this, I actually got the spec for the crystal; 12MHz, Load Capacitance:16 ~ 20pF, Tolerance/Stability: 30-50ppm, Package: HC-49S, ESR: 50 ohm Max, Drive Level: 500uW Max

I don't think the package needs to be exactly HC-49S as there seems to be quite a lot of variation on HC-49. Just as long as it's short, through hole, and fits. I found that once you start narrowing the specs the non-relevant packages tend to get automatically weeded out anyway.

[emiliom]

Would like to buy a MiSter Mulisystem but that doesn't seem like a possibility, so I thought I would have a go at having an assembled PCB made... But the provided BOM is terrible bordering on useless. I've spent a lot of time trying to decipher this and think I finally have a mostly complete parts list (but take this with a grain of salt as I really can't be sure, PCBWay also have no idea what most of the parts are either): https://pastebin.com/yS43Sz2w

One big problem is that most components seem to be low or no parts available, and while most parts should be easily changeable in terms of functionality, the pin positions and item sizes seem to be drastically different for replacement parts?

Absolutely no idea what J29 is. As mentioned the crystal seems like a challenge because they all look the same but have different electrical specs. The three LEDs next to the push button have different colours from videos I've seen, with the right hand LED (LED1) being green and the left hand LED (LED3) being orange/red, haven't seen the middle light come on in any videos. Not sure if the LEDs have any specific requirements.

To be honest I really have no idea what I'm doing with any of this stuff, really I would rather just buy one outright. However, if I can manage to figure this out it looks like it could be around £50 per assembled board?

Like you I've spent much time on this (weeks in fact). I've really just done my best to try and match parts based on what bits of product code were in the BOM. I looked at your list and I've got a few of the same components. Like you I nearly have a complete list but I don't know how much of it is right. You did me a huge favour though with the tactile switches, SW3,4 & 5, especially 4 & 5. I spent ages looking for something that looked right and just couldn't find anything - I was really stuck on those. You might want to amend the part slightly as the last character 'P' just seems to mean different types of packaging. You don't need the "embossed taper" so if you just get the bagged version (i.e. no P) it's a bit cheaper. I did have a candidate for SW3 but I think yours is probably right as the button is yellow. The one I found was blue, but the rest of the specs were very similar.

J29 just seems to be empty as far as I can see. From the description it looks like it should be a 2 pin header, and from what I could find it might be a Molex connector from the 'KK' series, but as the component doesn't seem to be on the board I guess we don't need it? The crystal I posted the specs for as per Terminus Tech's instructions (Load Capacitance:16 ~ 20pF, Tolerance/Stability: 30-50ppm, Package: HC-49S, ESR: 50 ohm Max, Drive Level: 500uW Max), so that should be ok to find. The LEDs that didn't say GREEN I assumed to be white, but doesn't sound like it from what you've said. I've not seen any videos, only static pictures. Is there a good one you can link to?

I'm mostly worried about not having specced the MOSFETs, Transistors, Power Load switch etc correctly. I recon with much of the other stuff, if the component isn't quite right it just won't work, but with the MOSFETs etc. I fear something might burn out, or worse damage other components on the board.

What I'm really stuck on now are the 2 vertical HDMI connectors. How did you work out the Amphenol G45A19011002HHR? I can't find a datasheet or even a picture of it!

I think it's going to come to more than £50 for a complete assembled board. I actually got my boards delivered today from JLCPCB so I can check a few things now and try and finish my list. I've got it all on an Excel spreadsheet so when it's done I'll post it. It has what I think are the key specs as well, so might help to find alternative parts if something is out of stock, and it calculates the total cost at the bottom so I'll be able to see it once it's done.

[LeeW]

To be clear, only the following items had enough information in the BOM to identify a part:
SW6 & SW7 (SNAC & VGA switch), SW2 (main power switch), U1 (Inverter), U2 & U3 (SDRAM), U4 (Power switch IC), U5 (USB Hub Controller), F1 (Fuse), P2 (uSDCard slot), P3 & P4 (Horizontal HDMI ports), P5 (MiSTer Multisystem Expansion port), P6 (SCART connector), P7 (SNAC USB port), J5 (Digital audio conn), J6 (5V Power conn), J23 & JP11 (Single horizontal USB 2.0), J27 & J28 (Ethernet conn), JP4 & JP9 & JP10 (Dual stack horizontal USB2.0), D1 (Zener Diode), Q21 & Q20 (MOSFET).

So for all of those parts I'm fairly confident in them being correct in the list I posted, other than U4 which I forgot to note should be an onsemi NCP380LSNAJAAT1G but due to low stock I changed this to a Texas Instruments part which seems to be identical in specs but slightly better. The fuse alternative I found seems to be identical in specs as well, other than being 7mm taller (I figured this should be fine).

The rest honestly are guesses based on visual references and the technical notes. Now that you mention it I think I may have actually given up on the vertical HDMI because nowhere seems to have any in stock and I may have just figured it had a high probability of being amphenol.

I found the following youtube video which shows closeups of the board in 4k resolution, but it is the beta version of the board so there's some small differences but is still a useful reference, useful information from about the 8m:30s mark (at this point it also shows the LED colours): https://www.youtube.com/watch?v=vDIz8WY6zLE

In this video and all of the others I've seen the middle LED doesn't seem to light up so I can't tell what it's supposed to be.

Here are my main sources for visual reference:

mms_board_4__03582.jpg

close_up__92298.jpg

de10_nano__67596.jpg

rear_ports__80084.jpg

Pages 58 and 59 of the multisystem manual pdf are also helpful:
https://www.retrocollective.co.uk/asset ... 2_V__1.pdf

[DeKay]

I'm mostly worried about not having specced the MOSFETs, Transistors, Power Load switch etc correctly. I recon with much of the other stuff, if the component isn't quite right it just won't work, but with the MOSFETs etc. I fear something might burn out, or worse damage other components on the board.

What is it that confuses you about things like the MOSFETs? The 23005.xls file seems to clearly denote these. For example, Q20 and Q21 are DMP2066LSN-7, and DigiKey has 140,499 of them in stock right now.

https://www.digikey.ca/en/products/deta ... -7/1964690

Edit: same information on 23005.pdf. Q20 & 21 are clearly shown at the top of Page 1 of the schematic.

[emiliom]

I'm mostly worried about not having specced the MOSFETs, Transistors, Power Load switch etc correctly. I recon with much of the other stuff, if the component isn't quite right it just won't work, but with the MOSFETs etc. I fear something might burn out, or worse damage other components on the board.

What is it that confuses you about things like the MOSFETs? The 23005.xls file seems to clearly denote these. For example, Q20 and Q21 are DMP2066LSN-7, and DigiKey has 140,499 of them in stock right now.

https://www.digikey.ca/en/products/deta ... -7/1964690

Edit: same information on 23005.pdf. Q20 & 21 are clearly shown at the top of Page 1 of the schematic.

Q21 & Q22 are easy as the exact code is right there, but the others aren't that straight forward. For Q3-10 for example, if you search DigiKey for BSS138 you get 5 components with the exact same code but slightly different specs. For Q1 & Q2 if you search for BC847 & BC848 you get multiple matches on different sites that are variations of these 2 base codes. For Q19, I can find a match for MMSS8550H (MMSS8550-H-TP I guess), but if I search for the LibRef BC856AL you also get multiple matches that are a variation of BC856AL. Not sure what the LibRef means, but for some other components on the list it's been the product code, so I have some doubt. I've found "matches" for all of them but I do have a nagging doubt.

[emiliom]

To be clear, only the following items had enough information in the BOM to identify a part:
SW6 & SW7 (SNAC & VGA switch), SW2 (main power switch), U1 (Inverter), U2 & U3 (SDRAM), U4 (Power switch IC), U5 (USB Hub Controller), F1 (Fuse), P2 (uSDCard slot), P3 & P4 (Horizontal HDMI ports), P5 (MiSTer Multisystem Expansion port), P6 (SCART connector), P7 (SNAC USB port), J5 (Digital audio conn), J6 (5V Power conn), J23 & JP11 (Single horizontal USB 2.0), J27 & J28 (Ethernet conn), JP4 & JP9 & JP10 (Dual stack horizontal USB2.0), D1 (Zener Diode), Q21 & Q20 (MOSFET).

Agree, except with D1 I had a query - I found multiple matches with different power dissipations. In the end after a conversation with ChatGPT I went with the higher power dissipation.

So for all of those parts I'm fairly confident in them being correct in the list I posted, other than U4 which I forgot to note should be an onsemi NCP380LSNAJAAT1G but due to low stock I changed this to a Texas Instruments part which seems to be identical in specs but slightly better. The fuse alternative I found seems to be identical in specs as well, other than being 7mm taller (I figured this should be fine).

I found the OnSemi U4 at Mouser. They've got about 500 right now. It's not a huge amount of stock but it doesn't seem to be dropping rapidly at the mo. The Bourns fuse they also currently have at Mouser (around 2000).

The rest honestly are guesses based on visual references and the technical notes. Now that you mention it I think I may have actually given up on the vertical HDMI because nowhere seems to have any in stock and I may have just figured it had a high probability of being amphenol.

Bugger. I was hoping you'd found the datasheet for the vertical HDMI connector. That's the last one I'm missing. I can't find one where the holes seem to align with the pins. I'm going to have another look just in case. Alternative might have to be a very short HDMI cable to connect the board to the DE-10?

I found the following youtube video which shows closeups of the board in 4k resolution, but it is the beta version of the board so there's some small differences but is still a useful reference, useful information from about the 8m:30s mark (at this point it also shows the LED colours): https://www.youtube.com/watch?v=vDIz8WY6zLE

In this video and all of the others I've seen the middle LED doesn't seem to light up so I can't tell what it's supposed to be.

I recon I probably saw that video on release but forgot about it so thanks for that. LEDs I just marked up as green or white so I'll have to change the relevant ones.

Cheers for the links.

[DeKay]

Bugger. I was hoping you'd found the datasheet for the vertical HDMI connector. That's the last one I'm missing. I can't find one where the holes seem to align with the pins. I'm going to have another look just in case. Alternative might have to be a very short HDMI cable to connect the board to the DE-10?

This vertical HDMI connector at AliExpress looks like it will do the trick. Inexpensive as well. The drawing shows a 1.6mm gap between the two horizontal rows of pins and that seems to more or less agree with what I measured off the PCB layout. The CUI Devices HD03-19 part you are probably looking at seems to show this dimension as 1.2mm, but I think that is actually the gap between the two attachment tabs on either side of the connector body. That doesn't matter for us because the hole for these on the PCB is a single slot vs two holes on each side.

https://www.aliexpress.com/item/1005003278040365.html

The same connector from another seller but the shipping is much more expensive, at least for where I live.

https://www.aliexpress.com/item/1005005178668059.html

[LeeW]

So it turns out that the github repo has some high quality images as well that I must have somehow missed before: https://github.com/Heber-co-uk/Multisys ... ain/images

The 2 HDMI male connections on the PCB is a kind of simple HDMI bridge that you then chop out of the main PCB and use as a bridge from the DE10 to the Multisystem board. Similar to how the official kit also ships with a very short Ethernet cable and USB cable. So you could ignore these and just get a short cable instead.

Okay so this is where I'm at on this:
https://docs.google.com/spreadsheets/d/ ... ingle=true

I believe that the exact capacitors and resistors used shouldn't matter as long as they match the specified capacitance and resistance respectively, right? Or are there other factors I need to consider?

The headers look to be standard 2.54mm pitch square pins and I'm pretty sure they are basically just metal pins and so don't need any special consideration.

As emiliom says Q1 to Q10 are stated as generic MOSFETs (e.g. BC848) is this a similar situation in that basically any (matching the given type) will get the job done? Because there's many variants available, is this just a lower quality vs higher quality thing?

Edit: I'm also thing that D1 specifics don't matter too much. And I found a video showing that the middle LED is also orange/red: https://youtu.be/qx45r-BRHxY?t=576

[DeKay]

Q21 & Q22 are easy as the exact code is right there, but the others aren't that straight forward. For Q3-10 for example, if you search DigiKey for BSS138 you get 5 components with the exact same code but slightly different specs. For Q1 & Q2 if you search for BC847 & BC848 you get multiple matches on different sites that are variations of these 2 base codes. For Q19, I can find a match for MMSS8550H (MMSS8550-H-TP I guess), but if I search for the LibRef BC856AL you also get multiple matches that are a variation of BC856AL. Not sure what the LibRef means, but for some other components on the list it's been the product code, so I have some doubt. I've found "matches" for all of them but I do have a nagging doubt.

LibRef means "Library Reference" and is just a name that they have given to that part in their internally developed library. Use it as a clue but don't expect to find that name at DigiKey or anything. I mean... they misspelled "ZENNER SOT23" for the D1 BZX84C5V1. I don't really know anything about Altium, but I suspect that BC846AL_1 is just a generic name for the BC846/7/8 that have a similar schematic symbol and footprint, just like RES or RESISTOR DIP 4. The specific vendor part number must be specified somewhere else that we don't have access to.

Q1 and Q2 are a wee bit tricky in that the A/B/C variants have different gains on the datasheets. I haven't analyzed the circuit but it might be that the design isn't sensitive to the transistor gain so it might not matter.

I'd say your guess for the MMSS8550H is correct. -TP just means it is provided in "Tape & Reel", 3000 parts per reel for this particular guy. If you need less, places like DigiKey just cut what you need off that reel. The H is more important in that it specifies the gain, so good call.

Taking a very quick look at the BSS138, there are indeed a pile of them on Digikey.

https://www.digikey.com/en/products/fil ... YAMwAObvKA

In this application it seems they are being used as level shifters in a low voltage, low current situation. So whether you order a Diodes Inc BSS138-7-F rated for 200mA or a BSS138K-13 rated for 310mA doesn't matter. About the only difference here is you save ten cents per part on the former. As long as the package type matches here, you are probably ok (SOT23, or SOT23-3 which is generally compatible PCB footprint wise).

[DeKay]

I believe that the exact capacitors and resistors used shouldn't matter as long as they match the specified capacitance and resistance respectively, right? Or are there other factors I need to consider?

Capacitors have a voltage rating. It seems that the maximum voltage used in this design is 5V, so you'll want to make sure that the caps you specify are rated for 2x that. The caps look to be basic decoupling capacitors using in millions of designs, so you'll know you've found the right ones when places like DigiKey show a bazillion of them in stock.

Resistors have a power rating but that is essentially determined by the package size. They also have a tolerance. A 5% tolerance is typically safe, unless you are in a sensitive analog application where the specific value is very important. Schematics will often flag specific resistors that might require a tolerance of 1%, for example.

I was going to say but it looks like you might be a step ahead of me - the VGA connector to circuit board footprint is not a standard. IIRC, TubeTime on Twitter ran into this recently. So double-checking the selected part's footprint to the board is a good idea.

[DeKay]

The 2 HDMI male connections on the PCB is a kind of simple HDMI bridge that you then chop out of the main PCB and use as a bridge from the DE10 to the Multisystem board. Similar to how the official kit also ships with a very short Ethernet cable and USB cable. So you could ignore these and just get a short cable instead.

Could mess things up once you try fit the assembly into a case though, especially those they have designed. See Page 15 of their manual for a picture.

The headers look to be standard 2.54mm pitch square pins and I'm pretty sure they are basically just metal pins and so don't need any special consideration.

Gold plated header pins wouldn't be a bad idea.

[emiliom]

Bugger. I was hoping you'd found the datasheet for the vertical HDMI connector. That's the last one I'm missing. I can't find one where the holes seem to align with the pins. I'm going to have another look just in case. Alternative might have to be a very short HDMI cable to connect the board to the DE-10?

This vertical HDMI connector at AliExpress looks like it will do the trick. Inexpensive as well. The drawing shows a 1.6mm gap between the two horizontal rows of pins and that seems to more or less agree with what I measured off the PCB layout. The CUI Devices HD03-19 part you are probably looking at seems to show this dimension as 1.2mm, but I think that is actually the gap between the two attachment tabs on either side of the connector body. That doesn't matter for us because the hole for these on the PCB is a single slot vs two holes on each side.

https://www.aliexpress.com/item/1005003278040365.html

The same connector from another seller but the shipping is much more expensive, at least for where I live.

https://www.aliexpress.com/item/1005005178668059.html

I'm an idiot. Last night I realised I'd been filtering my search for this by female instead of male...what a muppet! No wonder I couldn't find a match!
Good spot, and the first one is dirt cheap shipping to the UK. I found these as well at LCSC which might be a good option if buying multiple components from them as they have a budget international shipping option which is 2-3 weeks:

https://www.lcsc.com/product-detail/D-S ... 68715.html
https://www.lcsc.com/product-detail/D-S ... 62411.html
https://www.lcsc.com/product-detail/D-S ... 11355.html
https://www.lcsc.com/product-detail/D-S ... 04144.html

[emiliom]

The 2 HDMI male connections on the PCB is a kind of simple HDMI bridge that you then chop out of the main PCB and use as a bridge from the DE10 to the Multisystem board. Similar to how the official kit also ships with a very short Ethernet cable and USB cable. So you could ignore these and just get a short cable instead.

I think we're ok for these now. Could use a short cable but as DeKay said might be an issue packing it in. It does look a bit tight on the right hand side. Regardless it does look like we got multiple options for this now.

The headers look to be standard 2.54mm pitch square pins and I'm pretty sure they are basically just metal pins and so don't need any special consideration.

That's what I went with too. As you say, they all seem to be 2.54mm.

[emiliom]

In this application it seems they are being used as level shifters in a low voltage, low current situation. So whether you order a Diodes Inc BSS138-7-F rated for 200mA or a BSS138K-13 rated for 310mA doesn't matter. About the only difference here is you save ten cents per part on the former. As long as the package type matches here, you are probably ok (SOT23, or SOT23-3 which is generally compatible PCB footprint wise).

I just tried to match the code as exactly as possible as I didn't know which ones to pick. I guess I should be ok from what you've said. I wasn't sure if you had to match the amperage or just had to "cover" it. The ones I found were rated 220mA. Is that a general thing with diodes - as long as you are at or above the minimum required amperage then you're ok?

[emiliom]

I believe that the exact capacitors and resistors used shouldn't matter as long as they match the specified capacitance and resistance respectively, right? Or are there other factors I need to consider?

Capacitors have a voltage rating. It seems that the maximum voltage used in this design is 5V, so you'll want to make sure that the caps you specify are rated for 2x that. The caps look to be basic decoupling capacitors using in millions of designs, so you'll know you've found the right ones when places like DigiKey show a bazillion of them in stock.

When you say 2x, is that 2x or higher, or does it have to be exactly 2x? I think I've gone a bit overkill with mine as I went with higher voltage ratings. Basically I tried to get them all with a 5% tolerance, except for C16/19/22 - the best I could do there was 20%. That one was actually specced in the BOM at 10V, but no voltage mentioned for the others so I thought they might be different.

Resistors have a power rating but that is essentially determined by the package size. They also have a tolerance. A 5% tolerance is typically safe, unless you are in a sensitive analog application where the specific value is very important. Schematics will often flag specific resistors that might require a tolerance of 1%, for example.

I went with 1% on all mine and again I think overspeced the max voltage (75) and power dissipation (330mW). But I guess that just means they cost more.

I was going to say but it looks like you might be a step ahead of me - the VGA connector to circuit board footprint is not a standard. IIRC, TubeTime on Twitter ran into this recently. So double-checking the selected part's footprint to the board is a good idea.

I can confirm that the Wurth 618015330923 definitely fits. Only thing I didn't realise it was rated for 60VAC. But my understanding is that 60VAC = 60V RMS, and as the Multisystem only uses 5V that should be ok. Would my logic be correct here?

[emiliom]

I think I have one last point of confusion. For P3/P4, LeeW has the Amphenol 10029449-001RLF HDMI connector listed, and i have the Amphenol 10029449-111RLF. I can't see any difference in the electrical specs, yet one is nearly half the price of the other. They both have gold plated contacts. Only obvious difference I can see is the minimum operating temperature (-55 vs -20). The datasheet isn't especially helpful as it seems to be the same for both.

Would the operating temp account for such a difference in price? I can't see any real reason to go for one over the other, they look pretty much the same:
https://www.mouser.co.uk/ProductDetail/ ... KSqQ%3D%3D
https://www.mouser.co.uk/ProductDetail/ ... FaXA%3D%3D

[DeKay]

I just tried to match the code as exactly as possible as I didn't know which ones to pick. I guess I should be ok from what you've said. I wasn't sure if you had to match the amperage or just had to "cover" it. The ones I found were rated 220mA. Is that a general thing with diodes - as long as you are at or above the minimum required amperage then you're ok?

These aren't diodes, they are FETs from a company called Diodes Inc. There are a lot of other things to consider when it comes to FETs, like the gate to source turnon voltage. But I would think when you are choosing within the same family, the differences will come down to packaging, current capacity, and maybe operating temperature range. Current-wise, you want to size the device with some margin. Again, something like a minimum 2x safety factor is probably fine.

When you say 2x, is that 2x or higher, or does it have to be exactly 2x? I think I've gone a bit overkill with mine as I went with higher voltage ratings. Basically I tried to get them all with a 5% tolerance, except for C16/19/22 - the best I could do there was 20%. That one was actually specced in the BOM at 10V, but no voltage mentioned for the others so I thought they might be different.

When I said 2x higher, I meant 2x higher minimum for capacitor rated voltage vs. circuit operating voltage. The board takes a 5V input. If the BOM specced a 10V rated part, that is 2x. Makes sense.

When I was talking tolerance, the 5% number I tossed out was the resistance value for resistors. It is a lot harder to buy capacitors that have a tight tolerance for their capacitance, and a tight tolerance (especially for decoupling capacitors) is unnecessary in the first place. A 20% tolerance for capacitors is pretty common. FYI, decoupling capacitors are those you see on schematics that are connected to just power, ground, and maybe other decoupling capacitors. All those on Page 2 and Page 5, for example.

Resistors have a power rating but that is essentially determined by the package size. They also have a tolerance. A 5% tolerance is typically safe, unless you are in a sensitive analog application where the specific value is very important. Schematics will often flag specific resistors that might require a tolerance of 1%, for example.

I went with 1% on all mine and again I think overspeced the max voltage (75) and power dissipation (330mW). But I guess that just means they cost more.

That is overspecced for sure and besides adding cost, it probably makes them a little harder to source. I'd relax your resistor selections to 5% tolerance.

I can confirm that the Wurth 618015330923 definitely fits. Only thing I didn't realise it was rated for 60VAC. But my understanding is that 60VAC = 60V RMS, and as the Multisystem only uses 5V that should be ok. Would my logic be correct here?

That will be fine.

I think I have one last point of confusion. For P3/P4, LeeW has the Amphenol 10029449-001RLF HDMI connector listed, and i have the Amphenol 10029449-111RLF. I can't see any difference in the electrical specs, yet one is nearly half the price of the other. They both have gold plated contacts. Only obvious difference I can see is the minimum operating temperature (-55 vs -20). The datasheet isn't especially helpful as it seems to be the same for both.

Would the operating temp account for such a difference in price? I can't see any real reason to go for one over the other, they look pretty much the same:
https://www.mouser.co.uk/ProductDetail/ ... KSqQ%3D%3D
https://www.mouser.co.uk/ProductDetail/ ... FaXA%3D%3D

I wouldn't even call that a datasheet. I'd call it garbage. It is possible that there is something else besides operating temperature range. The more expensive version might be higher quality and rated for more connect / disconnect cycles. But can't tell from that crappy documentation. I suspect better datasheets for these parts exist somewhere else that would allow you to make a better decision.

[emiliom]

Current-wise, you want to size the device with some margin. Again, something like a minimum 2x safety factor is probably fine.

Thing is I don't know for sure what the '1x' value is. But I suppose, taking BC848 as an example, most of the variants share some common values such as 100mA collector current and 30V emitter / base voltage etc., so we're probably safe with a 'common' variant?

That is overspecced for sure and besides adding cost, it probably makes them a little harder to source. I'd relax your resistor selections to 5% tolerance.

Actually finding them wasn't too much trouble - the filtering selectors on websites really help. What was tricky was trying to get all of them the same tolerance AND the same manufacturer. I thought if they all came from the same manufacturer they'd have the same build quality, similar characteristics etc. But yes, that was a little tricky. And they are about 10 times the price of lower spec resistors for sure! But I did also list some cheaper alternatives.

I wouldn't even call that a datasheet. I'd call it garbage. It is possible that there is something else besides operating temperature range. The more expensive version might be higher quality and rated for more connect / disconnect cycles. But can't tell from that crappy documentation. I suspect better datasheets for these parts exist somewhere else that would allow you to make a better decision.

Yes it was a bit naff. It was more like sales bumf. I found a proper datasheet here:
https://www.amphenol-cs.com/media/wysiw ... 029449.pdf
It looks like the '001' version has brass contacts, 30 microinches gold plated, and a steel shell, and the '111' version is phosphor bronze, only flash plated and a brass shell. Can't say I know if steel is better than brass in this instance but certainly the flash plating is going to be cheaper. It's only 3 microinches. Think I'll go with the '001' Lee found.

[emiliom]

Ok, so I think I've finished my list. It's in an Excel spreadsheet and I've included multiple components of the same part for many of them so that there are alternatives, mainly in case I wanted to purchase from different places. You can get free shipping if you make sure you reach the minimum order value. It's got a lot of stuff people can ignore such as my notes and some of the component specs, but I found it useful when listing multiple components to help deciding on which ones to pick.

It's pre-filtered so that it's currently showing what I've called Main Parts and Preferred parts. So Main means is this an alternative or not. If it's a main part then the cell says 'Yes' and if not it says 'Alt'. The Preferred column allows you to select which 'Main' part (if there are multiple) is the one you would like. This way I can filter as follows:

Main->Yes
Preferred->Yes

...and get one of each part. But you might want to change Preferred parts depending on location, cost, etc., or add your own additional Main parts. For example, I've listed a complete set of more expensive Vishay resistors from Mouser and then some cheaper MultiComp Pro ones from Farnells. You can filter as required. It includes all the manufacturers part numbers and vendor specific part numbers so everything should be relatively easy to find. One thing to note is that even though I have listed prices they do seem to change on an almost daily basis on UK sites and I'm guessing that's because pretty much everything is actually being priced in dollars and just converted based on the exchange rate, but they should be roughly right.

One thing I added was the official Mean Well PSU as well in case people didn't know which one to get.

Please feel free to point out any errors, better parts, etc. I can't guarantee it's 100% right but given the help from the forum members I think it must be close. I guess we'll see when I finish building it.
I can't believe it's finished! I never thought I was going to find those tactile switches or the vertical HDMI connector, so thanks LeeW and DeKay - I would have been totally stuck.

EDIT (01/08/2023): I've changed the BOM to add a couple of extra parts pointed out by LeeW, but most importantly to update the info for SW6 & SW7 which was wrong on the original BOM file. It gave the product code of the vertical version of the switch rather than the right angle version.

EDIT (08/09/2023):
1) Part U1 has been changed because it was incorrect. Fitting the '07' version rather than the correct '04' version results in only half the SDRAM being available to the MiSTer.
2) I've separated out green LED1 onto it's own line as this needs to be a very specific spec it would seem in order to be able to shine though to the top of the hole. A brighter LED with a narrower viewing angle is required.
3) A note has been placed on the 2 x 20 pin headers (JP1, JP7) about having long though hole pins that need to be snipped.

23005 v22-3 - Publish.xlsx

[DeKay]

Let us know how your build goes once all your parts come in! I won't be making one, but that is mostly because I don't have a MiSTer

Not yet anyway.

What would be sweet is if someone were to convert this design to Kicad from Altium. That would really unleash people's ability to modify this design going forward. Altium is a high end tool for a high end price and not very accessible for most hackers.

[emiliom]

Let us know how your build goes once all your parts come in! I won't be making one, but that is mostly because I don't have a MiSTer

Will do. I've placed all my orders now so I just have to wait. I got away with just one shipping cost from LCSC as I had to get the vertical HDMI connectors from there. Could have gone with the Ali Express one but I couldn't wait 2 months for shipping! As it is I shouldn't have to wait more than 2 - 2.5 weeks at most.

What would be sweet is if someone were to convert this design to Kicad from Altium. That would really unleash people's ability to modify this design going forward. Altium is a high end tool for a high end price and not very accessible for most hackers.

Not that I know a lot about circuit design, but I did initially think to myself, "yeah, I should have a look at this Altium software...at least it should let me get a good view of the circuit design". Then I saw the price.

[LeeW]

BTW I'm looking back over the parts again and was trying to find good information about the crystal specifications and finally ended up finding the FE2.1 used in another PCB design which has some recommended crystals, well "reference" parts: https://github.com/MiSTer-devel/Wiki_Mi ... mbly-(DIY)

So... yeah looks like the requirements on the crystal may not be as high as you were told? From the schematics there's nothing in between the crystal and FE2.1 chip in either design, and the two crystals recommended above only have a max drive level of 200 and 300, and both have an ESR of 80 Ohms. The VGA connector also looks like the reference one from the above link, the Omron XM4L-1542-132.

And I've noticed that the BOM code for SW6 & SW7 is wrong! Although I guess the pins/footprint is correct. It has the part number for the vertical switch, while the correct part is the horizontal/right-angle switch C&K OS102011MA1QN1. This is the non-shorting switch which is also specified on the above PCB, but there is a also a shorting version (OS102011MA1QS1) available which could work as well? Not sure on the implications of shorting vs non-shorting here.

Also after looking into it more I'm pretty sure that the headphone port on the Multisystem is the KLBR 4 if you were trying to exactly match the official board.

[emiliom]

...looks like the requirements on the crystal may not be as high as you were told? From the schematics there's nothing in between the crystal and FE2.1 chip in either design, and the two crystals recommended above only have a max drive level of 200 and 300, and both have an ESR of 80 Ohms.

Those specs came straight from Terminus so I think I'm going to stick with those. But if it is higher spec, a higher max drive level and lower ESR I would think would be ok? Bit like over speccing the resistors? Also I think that I should be able to spot quite quickly if my USB devices are having issues so that should be quite easy to test.

The VGA connector also looks like the reference one from the above link, the Omron XM4L-1542-132.

I haven't added the Omron to my list because I can't find it anywhere. DigiKey, Mouser, Farnell, LCSC... all got nothing, and DigiKey shows it as obsolete.

And I've noticed that the BOM code for SW6 & SW7 is wrong! Although I guess the pins/footprint is correct. It has the part number for the vertical switch, while the correct part is the horizontal/right-angle switch C&K OS102011MA1QN1. This is the non-shorting switch which is also specified on the above PCB, but there is a also a shorting version (OS102011MA1QS1) available which could work as well? Not sure on the implications of shorting vs non-shorting here.

Good catch! I have updated my spreadsheet accordingly. I think it makes sense to go with the non-shorting version as the original BOM had the non shorting version (albeit the wrong switch), and as you say other designs also use non shorting.

Also after looking into it more I'm pretty sure that the headphone port on the Multisystem is the KLBR 4 if you were trying to exactly match the official board.

From the pictures I've seen of the KLBR 4 the outside of the socket is smooth while the one on the Heber board is ribbed (screw thread?) like the 4832.2320. It does take up to 1A though. I've added the KLBR 4 to the spreadsheet as well, although there isn't much stock that I could find. Farnell has 30, but I couldn't find it at all on DigiKey, Mouser and LCSC. Farnell has more coming soon, but it has a very long lead time if it goes out of stock.

[DeKay]

In this application it seems they are being used as level shifters in a low voltage, low current situation. So whether you order a Diodes Inc BSS138-7-F rated for 200mA or a BSS138K-13 rated for 310mA doesn't matter. About the only difference here is you save ten cents per part on the former. As long as the package type matches here, you are probably ok (SOT23, or SOT23-3 which is generally compatible PCB footprint wise).

I just tried to match the code as exactly as possible as I didn't know which ones to pick. I guess I should be ok from what you've said. I wasn't sure if you had to match the amperage or just had to "cover" it. The ones I found were rated 220mA. Is that a general thing with diodes - as long as you are at or above the minimum required amperage then you're ok?

Looked at this circuit further and can confirm that the lower current rated BSS138 good for 200mA will be fine. This circuit is inline with the FPGA that itself can only handle 40 mA per pin absolute max..

[LeeW]

From the pictures I've seen of the KLBR 4 the outside of the socket is smooth while the one on the Heber board is ribbed (screw thread?) like the 4832.2320. It does take up to 1A though. I've added the KLBR 4 to the spreadsheet as well, although there isn't much stock that I could find. Farnell has 30, but I couldn't find it at all on DigiKey, Mouser and LCSC. Farnell has more coming soon, but it has a very long lead time if it goes out of stock.

Hmm... You may be right, I could have sworn it was smooth but now I look back and it does have a thread. Could have been looking at different pictures. Other than that they seem to be virtually identical in appearance and pin placement.

Any updates on your boards?

Looked at this circuit further and can confirm that the lower current rated BSS138 good for 200mA will be fine. This circuit is inline with the FPGA that itself can only handle 40 mA per pin absolute max..

Thanks for the clarification. Do you have any insight into the crystal? As mentioned the same chip is used in the MiSTer FPGA stack but has a different specs to what emiliom was told.

[emiliom]

From the pictures I've seen of the KLBR 4 the outside of the socket is smooth while the one on the Heber board is ribbed (screw thread?) like the 4832.2320. It does take up to 1A though. I've added the KLBR 4 to the spreadsheet as well, although there isn't much stock that I could find. Farnell has 30, but I couldn't find it at all on DigiKey, Mouser and LCSC. Farnell has more coming soon, but it has a very long lead time if it goes out of stock.

Hmm... You may be right, I could have sworn it was smooth but now I look back and it does have a thread. Could have been looking at different pictures. Other than that they seem to be virtually identical in appearance and pin placement.

Yep. I tried the 4832.2320 on the PCB and it fits exactly. It comes with a little...well I'd have to call it either a spacer or a round nut that screws onto the thread. I can't say I'm sure what it's for. Certainly on the Heber board it's not present. It's not shown on the Farnell page but you can see it on the Mouser page: https://www.mouser.co.uk/ProductDetail/ ... KNAA%3D%3D
But without that it does look identical to the one on the Heber board.

Any updates on your boards?

Only that I'm waiting for parts now. PCBs are here. I expect to get most of my components over the next 2 or 3 days, but I have a few coming on an LCSC order from China that only shipped yesterday so it'll take a couple of weeks to get here yet I think.

[DeKay]

Looked at this circuit further and can confirm that the lower current rated BSS138 good for 200mA will be fine. This circuit is inline with the FPGA that itself can only handle 40 mA per pin absolute max..

Thanks for the clarification. Do you have any insight into the crystal? As mentioned the same chip is used in the MiSTer FPGA stack but has a different specs to what emiliom was told.

I don't know where emiliom got his information from. Perhaps he contacted the vendor directly? Anyhoo, the Terminus Tech datasheet is poor in that it doesn't spec the requirements for the crystal. It would seem to me that we would be safe in just copying what was used on the MiSTer USB Hub Assembly (DIY) design. We know that works. I suspect the Heber folks did the same.

Quite possible that the chip will work with either type of crystal. We'll know soon!

[emiliom]

Do you have any insight into the crystal? As mentioned the same chip is used in the MiSTer FPGA stack but has a different specs to what emiliom was told.

I don't know where emiliom got his information from. Perhaps he contacted the vendor directly?

Yes, crystal specs came direct from Terminus. I contacted them when I couldn’t find the specs in the data sheet.