Amiga 600 schematics nearly put into Kicad

[Mick]

I need to get a real board and check the dimensions for holes first but if you could build one and test one out once it's finished that would make things a lot easier for me.

I was hoping to offload the rest of the work to someone else but I'm fairly bored to be honest and I'm not 100% sure if he'll have the time or inclination to do it, he could have just been humouring me and didn't want to say no so if I work on the assumption that he won't there's a bigger chance of it being finished by at least one of us.

[hese]

Originally Posted by Mick

I was hoping to offload the rest of the work to someone else but I'm fairly bored to be honest and I'm not 100% sure if he'll have the time or inclination to do it, he could have just been humouring me and didn't want to say no so if I work on the assumption that he won't there's a bigger chance of it being finished by at least one of us.

As I said to you, I'll start working on the board designs (A600 and A1200) when I can. I wasn't humoring you. I did mention that I'm currently very busy with other things and can't start working on them just yet. All the spare time since the spring has gone to the service backlog cleared and there's still plenty of work to be done. Sorry that I haven't been able to work on the designs as fast as you liked but I simply don't have the time to do that just yet.

Are you bored because the dimensions and drill holes of the A600 board haven't been verified yet? Or because the A1200 board hasn't been routed? If it's the A600, I can verify these this weekend unless someone else wants to chime in before that. But if it's the A1200, that will have to wait a bit longer.

If you want to assign these to someone else, that's also alright with me.

[Mick]

Hi hese, I just meant I'm bored generally (hence my doing this whole thing in the first place) and so I was going to have a go finishing it myself since I have nothing better to do and wasn't 100% sure if you would, it's nothing personal just that people don't always do what they say they are going to do.

I hadn't even mentioned you by name because I didn't want to put any expectancy on you but as you've reassured us I'll send you some newer files since I've spent the last few days re-arranging the A600 components as I found a way to measure their location more accurately (using GIMP), plus I've polished a few things up (fixed silkscreen on modulator going over holes etc) and I hadn't finished arranging reference labels on A1200.

Like I said before I think you can do a much better job so I'm happy to leave it to you and actually feel a lot more comfortable in doing so.

[DJBase]

Its always nice to see new boards which will be also open and not closed but I always prefer 100% original designs to restore broken boards. Everyone tries to change something (that doesn't mean it would make no sense) but for me I would like to see more 1:1 original board designs as replacement which are open for everyone.

So great work Mick! Go ahead!

[Acill]

Mick,
I would be happy to build one up at my expense for you. I am currently out in Japan doing a job for the Japanese but get home on the 28th. If Hese or some of the other guys are easier for you to have do it I understand that too. Just let me know. You can find me at my site acill.com

[Mick]

I'll wait and see what hese does first, like I said it was my preference to let him finish it since he has already brought a few excellent boards to fruition. My specialty is just doing the CAD part of it more than anything else.

[hese]

Here are the board dimensions, drill hole locations and diameters of the A600 rev 1.5 motherboard. These are measured with a digital caliper by hand so they may not be 100% accurate but should be very close. All measurements are in inches.

Board dimensions:
A = 12.45"
B = 7.6215"
C = 6.475"
D = 2.9035"
E = 0.786"
F = 2.045"
G = 1.578"
H = 1.450"
I = 1.475"
J = 2.795"
K = 3.380"

Indent between J and K is 0.100".

Drill holes:
hole 1: x = 0.195"   y = 0.200"  d = 0.125"  (x,y from the bottom left corner)
hole 2: x = 0.235"   y = 0.250"  d = 0.135"  (x,y from the bottom middle corner)
hole 3: x = 1.208"   y = 0.250"  d = 0.125"  (x,y from the bottom right corner)
hole 4: x = 1.5675"  y = 2.400"  d = 0.135"  (x,y from the bottom right corner)
hole 5: x = 0.1925"  y = 0.865"  d = 0.125"  (x,y from the top right corner)

hole 6: x = 2.450"   y = 1.250"              (x,y from the top left corner)
hole 7: x = 2.450"   y = 4.175"              (x,y from the top left corner)
hole 8: x = 6.125"   y = 1.250"              (x,y from the top left corner)
hole 9: x = 6.125"   y = 4.175"              (x,y from the top left corner)

Holes 6-9 are 0.135" wide and 0.065" tall.

d = hole diameter

top left corner      = where A and B cross
bottom left corner   = where B and C cross
bottom middle corner = where C and D cross
bottom right corner  = where I and J cross
top right corner     = where A and K cross

This is all I can do for now, I haven't had time to check the KiCad designs. Hope this helps.

[Mick]

That's great, I'll update my files. I noticed earlier that the edge connectors have angled corners as well so I'll do that while I'm at it.

[Mick]

If you could find the time to measure pin 1 locations of all of the external connectors that would be excellent but no rush.

[Mick]

Just a quick update as I've had a few PM's, the files I uploaded were a sort of snapshot of a work in progress, they aren't finished. I'd like to perfect it as much as possible and test it out before releasing the files again.

I'm currently manually routing the power again as it seems to give autorouting a hernia, I'm doing it a bit more accurately this time like I recently did the components. When I started laying out the A600 originally it was very much a learning process for me and after doing the A1200 I've become a bit better so I pretty much redid the A600 layout. I'll finish manually routing the power/polishing over the next few days and then resend the files to hese so he can look over the schematics and maybe check layout aspects when he has finished all of his work, once the schematics are checked and external connectors look okay in terms of alignments it should be nearly good to go with a bit of autorouting. If hese wants to be a guinea pig and maybe sell some PCB's as a thanks for helping me he has first dibs otherwise I'll have to arrange something myself.

Here it is as of right now:
https://i.postimg.cc/XJHh7f7p/Untitled.jpg

It probably looks much the same as before but it should be a bit more accurate now and I'm somewhat of a perfectionist so I feel better about it.

It's not a 100% identical reproduction but it's close enough for me and in terms of functionality it should be identical with the added bonus of the newer DAC that doesn't need the external band-pass filters and delay lines.

edit: the A600 keyboard chip is still a big problem for anyone looking to build from scratch, I think it would be better if you could use the A1200 one (is it possible?) as they're more readily available, it's beyond my ability though...

[Acill]

Nice work! I look forward to seeing if this will work to revive several bad A600 boards I have here. I have become quite good and doing board swaps now with the A1200, A2000, 3000 and 4000! This should be quick and easy once ready.

[Stedy]

Originally Posted by Mick

Just a quick update as I've had a few PM's, the files I uploaded were a sort of snapshot of a work in progress, they aren't finished. I'd like to perfect it as much as possible and test it out before releasing the files again.

I'm currently manually routing the power again as it seems to give autorouting a hernia, I'm doing it a bit more accurately this time like I recently did the components. When I started laying out the A600 originally it was very much a learning process for me and after doing the A1200 I've become a bit better so I pretty much redid the A600 layout. I'll finish manually routing the power/polishing over the next few days and then resend the files to hese so he can look over the schematics and maybe check layout aspects when he has finished all of his work, once the schematics are checked and external connectors look okay in terms of alignments it should be nearly good to go with a bit of autorouting. If hese wants to be a guinea pig and maybe sell some PCB's as a thanks for helping me he has first dibs otherwise I'll have to arrange something myself.

Here it is as of right now:
https://i.postimg.cc/XJHh7f7p/Untitled.jpg

It probably looks much the same as before but it should be a bit more accurate now and I'm somewhat of a perfectionist so I feel better about it.

It's not a 100% identical reproduction but it's close enough for me and in terms of functionality it should be identical with the added bonus of the newer DAC that doesn't need the external band-pass filters and delay lines.

edit: the A600 keyboard chip is still a big problem for anyone looking to build from scratch, I think it would be better if you could use the A1200 one (is it possible?) as they're more readily available, it's beyond my ability though...

Is there anything else you need from me?
The original Amiga schematics have a weird oscillator device, it is exceptionally rare that the enable pin is connected to ground to enable the device, the default is to leave the enable pin floating or pull it up to enable.

You might be able to use the same keyboard hack that the A1200 uses, you connect the KB_CLK and KB_DAT of the PC/Amiga keyboard device to the ODD CIA. Would need to think about this a bit more.

Sorry for not checking in earlier and answering the question on the oscillator, I'm on holiday so have many beers to try

[Mick]

Hi Stedy, I'm working with hese to try and get it released as I don't want to let the neglected A600 fans down.

I remember when I finished placing components there were two capacitors connected to the output pin of the oscillator and ground but they aren't present on the commercially released boards, I figured it was best to leave them in and maybe just not install anything there but I've since removed them altogether to keep things close to original.

hese is going to look at dimensions and get some boards manufactured and he'll either build one for me or Acill can be guinea pig. I'm more interested in the A1200 myself but the A600 proved to be a good stepping stone for me. I didn't even think I'd be able to do A600 at the start.

Thanks for your help.

[Acill]

Looking forward to seeing this get completed! I'm off once again on a work trip for a couple of weeks, but I am more than willing to help out if you need it.

[Mick]

Hi Acill, I have bought a motherboard off Ebay which will hopefully arrive in the next few days and I will try to use it to get the external connectors and holes as accurate as possible. hese has been a great help to me but I don't want to keep him from his own work. I will get some boards made myself and probably send you both one if they look okay, otherwise I fear this is going to get expensive.

What board manufacturer do people use? is pcbway any good? I need one who will harden the edge connector.

With hese's help I've almost fully auto-routed the board:

1st layer - vertical signals
2nd layer - ground plane
3rd layer - vcc plane
4th layer - horizontal signals

I've also removed solder mask from the edge connector, didn't realise that needed to be done.

One thing I wonder about is some boards have a leaded capacitor across the CXA1145 DAC, should I add an SMD footprint for it on the back or just leave it? my board is based on 2D schematics.

[SteveMoody]

I've not tried pcbway but i've used https://jlcpcb.com to get a large 4 layer board made. Decently priced and good quality.

I don't know if they have any options for a hardened edge connector but there is an option on the quote page for gold plated fingers.

Edit: Added some photos

[Stedy]

Mick,

Using PCBShopper, a 4 layer board with gold fingers/hardened edge connector can be yours for the princely sum of £74, for a quantity of 5. These boards are Electroless Nickel Immersion Gold (ENIG) finished so they are harder (for the edge connector and flatter, ideal for SMT reflow using solder paste. The downside is they are tricky to hand solder as they are gold plated. You need to wet the pads (with solder) first to get a good joint when hand soldering.

If you don't want the gold fingers, you can get the boards for £60. Prices were from JLPCB. If you just want to check mechanical fit and test a basic 1MB A600 design, consider the cheaper option.

The leaded capacitor across the CXA1145 was probably a supply decoupling capacitor. Would need to see a photo to confirm.

[Mick]

This board has the capacitor (rev. 1.5), it may be that rev 2 fixed it?
http://amiga.resource.cx/photos/phot...res=hi&lang=en

edit: I think they fixed it with rev 2 by adding C461, is that right?

I looked at JLPCB before because kipper suggested it previously but they say on their website that they only do up to 300mmx300mm on more than 2 layers, unless their website is out of date ot something? How big was your board SteveMoody? I will look into the other suggestions. I'd rather take the gamble and get the edge connector hardened to begin with.

My ROM damaged board hasn't arrived from Ebay yet so I'm still in limbo.

edit: also, anyone know what C201 is for? I've not seen it installed on any boards.

[SteveMoody]

Originally Posted by Mick

I looked at JLPCB before because kipper suggested it previously but they say on their website that they only do up to 300mmx300mm on more than 2 layers, unless their website is out of date ot something? How big was your board SteveMoody?

I hadn't noticed the limit on 4 layer boards before i uploded the gerber files for it but they didn't have any issues.
My board is 360x240mm

[Mick]

Oh great, I'll probably use JLPCB then. Thanks.

This is the page where they say 300x300mm, guess they need to update it.
https://jlcpcb.com/capabilities/Capabilities

My board for checking measurements is at the post office will get it tomorrow then I'll try to route it and order before the weekend.