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Re: A2000 Replica Build

Posted: Sat Apr 18, 2020 6:19 am
by Olem
Looks really good! Great job, love your plain, classic setup there. I'm getting one of those black PCBs from Rob, can't wait to get my hands on it. I might also...accidentially...have bought a defective A2000 :D . I blame the brandy and all the amiga love that's flowing in here <3

Re: A2000 Replica Build

Posted: Sat Apr 18, 2020 6:44 am
by grshaw
Buying a defective A2000 is a cost effective way of getting a case, power supply and floppy disk drives. Good thinking. :D

Re: A2000 Replica Build

Posted: Sun May 03, 2020 8:17 am
by Zippy Zapp
My board came in from the UK a few days ago. Now the fun task of ordering all the components. While I have most of the chips and sockets already, some connectors will be fun to source as I don't want to salvage them from my repaired A2000. I see the Floppie209 Amiga 2000 Remake has a BOM text file. Also the other project has an interactive HTML based BOM, which seems to be more helpful.

I am really excited to get this going and I hope it works.

Edit:
Does anyone that built one of these have the part numbers for the Zorro, Video and CPU Card Slots? Also if you have a part number for the 5 Pin DIN Keyboard connector that would be really helpful. Thanks!

Re: A2000 Replica Build

Posted: Mon May 04, 2020 6:23 am
by grshaw
Glad to see you are excited. It is a really fun project.

"I see the Floppie209 Amiga 2000 Remake has a BOM text file. Also the other project has an interactive HTML based BOM, which seems to be more helpful."

In fact, neither of these is 100%. I'm on a Discord Channel called Retro Tinkerers and a guy on there called Rob Krenicki has done a great job of puting together a BOM for the A2000 build. If you bought from Rob Taylor's Tindie shop then you may already be on there. You can download from Google Docs on this link:

https://docs.google.com/spreadsheets/d/ ... sp=sharing

Mouser part numbers are all in there.

zorro_sockets 571-2-5530843-2
ISA16 and Video Slots 571-5530843-3
CO-PROCESSOR_SLOT 571-1-5530843-0
KEYBOARD 806-KCDX-5S-S2

There is also this Component Locator, which is up to date with the most recent revision of the PCB from Floppie209. Really useful for working out where to place all the components.

http://locator.reamiga.info/locator.php?project=A2000

Re: A2000 Replica Build

Posted: Mon May 04, 2020 7:44 am
by Zippy Zapp
Awesome! Thanks @grshaw! I guessed on the expansion slots and fortunately I ordered the exact ones you listed.

I am only missing a few components now, like the crystal and a couple of connectors that I think I can salvage from a dead A500 board that I have. Buster chip may be a little different but I suppose I can borrow it from my other working A2000 since the board is going to go into that case anyway,

Now I just need to go through my huge Mouser order and compare it to the list you posted to make sure I didn't order some wrong components since I used the BOM.HTML in one of the other lists. LOL

Thanks for the help, most appreciated!

Re: A2000 Replica Build

Posted: Mon May 04, 2020 8:58 am
by grshaw
Now I just need to go through my huge Mouser order and compare it to the list you posted to make sure I didn't order some wrong components since I used the BOM.HTML in one of the other lists
I think the component list is pretty much the same, so you should be okay. There are some differences between the names of locations, for example, the newest revision of the board switches R1 + R2. The Kicad ibom.html has not been updated with that change for example. Rob Krenicki has also gone for different capacitor types too, but either type should be fine.

The new revision of the board supports SMD power leds on the +12V and +5V rails, so you will likely be missing those and the corresponding SMD resistors too. ( D402 + 403 and R402 + 403 ).

Re: A2000 Replica Build

Posted: Mon May 04, 2020 1:13 pm
by Zippy Zapp
grshaw wrote:
Mon May 04, 2020 8:58 am

The new revision of the board supports SMD power leds on the +12V and +5V rails, so you will likely be missing those and the corresponding SMD resistors too. ( D402 + 403 and R402 + 403 ).
I was wondering what those were for when I saw them on the board. My board is 1.8.5 so I think that is the latest. Its a nice option I will probably add. I missed a couple of Resistor Networks, like RP603-1 and a few of the components were out of stock at both Digi-Key and Mouser so I had to find alternatives which was pretty easy thanks to data sheets and product codes.

Re: A2000 Replica Build

Posted: Fri May 22, 2020 10:25 am
by Zippy Zapp
Hello. What RTC chip did you use and is your clock working correctly? I noticed in your latest picture you don't have the clock crystal or the VC800 trimmer capacitor installed. I have been reading the datasheets to the various RTC chips and what I don't understand is why the crystal and trimmer cap were necessary. According to the Oki and Epson RTC datasheets all the RTCs that were used have a built in clock crystal. And most use two 22pf caps for the clock. The EPSON chip that is listed on the BOM shows that the pins 16 and 17 are (Vdd) linked to pin 18 Vdd and state they should be left open circuit. That to me means there shouldn't be any thing connected to them.

The Oki MSM6242 chip (Original Spec chip from the schematics from Commodore) show that 16,17 to be XT and that a Crystal should be connected to these pins. I wish I completely understood this stuff because the chip datasheet also states that a crystal is built-in to the RTC Chip. Confused.

I got all the components on my build and should I start a new thread so as not to cloud up yours?

I tried to purchase new 23 pin motherboard Dsubs from iComp, as well as a couple other items and they are charging 47 Euros for shipping via DHL. Which is more then the items I was ordering and extortion level shipping, IMO. I have bought many things from them in the past and it is usually no more then 7-10 euros even for a motherboard. :cry: Oh well I have a few borked A500s that will need to be used. Those and a Buster is all I really need. I think the Vidiot is the same on the A500.

Re: A2000 Replica Build

Posted: Sun May 24, 2020 12:20 pm
by grshaw
What RTC chip did you use and is your clock working correctly? I noticed in your latest picture you don't have the clock crystal or the VC800 trimmer capacitor installed.
At the time of the previous photo in this thread, the Real Time Clock wasn't working. I have since got it working using a RTC-72421B from Epson https://www.mouser.co.uk/ProductDetail/ ... ApgA%3D%3D
I have been reading the datasheets to the various RTC chips and what I don't understand is why the crystal and trimmer cap were necessary. According to the Oki and Epson RTC datasheets all the RTCs that were used have a built in clock crystal. And most use two 22pf caps for the clock.
You are absolutely correct. If you are using a modern RTC chip, then the trimmer capacitor and the crystal are completely surplus to requirements. They were required back in the 80's and they have not been removed from the PCB.
The Oki MSM6242 chip (Original Spec chip from the schematics from Commodore) show that 16,17 to be XT and that a Crystal should be connected to these pins. I wish I completely understood this stuff because the chip datasheet also states that a crystal is built-in to the RTC Chip. Confused.
Definitely, the thing to go for is the Epson chip above and leave the trimmer capacitor and the crystal in VC800 and Y800 respectively unpopulated. The Epson chip is a pin for pin replacement for the 6242 but with those components included inside the package.
I tried to purchase new 23 pin motherboard Dsubs from iComp, as well as a couple other items and they are charging 47 Euros for shipping via DHL.
Yeah - that sounds like daylight robbery.
I think the Vidiot is the same on the A500.
Yes it is. I also used a Video Hybrid from an A500 and it worked absolutely fine.

Re: A2000 Replica Build

Posted: Sun May 24, 2020 2:36 pm
by Zippy Zapp
Right on, thanks for confirming all those bits, most appreciated.

I indeed did buy the Epson RTC 72421B so I will use that and am glad to not have to fiddle with a trimmer cap and oscilloscope to get it adjusted, what a hassle that would be.

I removed all the necessary bits from a borked A500 so I am good to go. The 23-pin RGB connector was the most difficult thing to remove since the pins are much thicker then the 23-pin floppy connector. I had to use a combination of desoldering station and hot air rework to get the sucker out. Major pain but it is good to go now. It would have been nice to use new connectors but yeah, I am not paying those kind of shipping charges. They put a note on the shipping page that some shippers where including "Danger Pay" in the rates because of the Pandemic. 7-8 times the previous rate is absurd.

Have you seen a note or a site or anything that shows what Mods were made to the floppie209 A2000 boards? All the revisions say with mods, I am just curious to know what mods they made beyond what is in the release notes. I know they added a diode and coin cell footprint to 1.8.5. But not sure what else they fixed from the 6.2 Base.

How is your system running? I hope it is still going strong.