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Assembly and Installation
A complete Bill Of Materials is not available at the moment, but Richard Körber put together this very nice document (Thanks!).
The community-maintained BOM for the A500++ should also be a close match.
Following are a few general indications.
Let's start with the items that are the hardest to obtain, since they are custom parts that were built on commission for Commodore and are no longer into production. You will either need to recover these from a failed board or buy them from someone.
The first thing you will need to recover are all the custom Commodore ICs, of course. You can use either a SuperDenise (MOS 8373) as on the A500+ (a PLCC chip from an A600 will also work with an adapter) or an "ordinary" Denise (MOS 8362Rx). As for the Agnus, an 8375 Agnus is required but there are different "models" of those and only the following ones are compatible:
- 390544-01 (PAL)
- 390544-02 (NTSC)
- 318069-10 (PAL)
- 318069-11 (NTSC)
These were used on A500+ and A600 computers. Other 8375 chips were used on A3000s and those are NOT compatible.
Only populate C99 if you are using a 318069-10 or -11 Agnus, otherwise do NOT solder anything in that position.
It would be relatively trivial to add support for older Agnuses. As with any other improvement, feel free to do it and open a Pull Request.
The Video and Floppy connectors are non-standard DB-23.
Maybe it was not a custom part, but the power connector is nowhere to be found today. Although, the board also accepts cheaper DIN-6 or DIN-8 connectors, but make sure to wire them properly.
While you are at it, you should recover the line filter (LF1) too, but you can also replace it with a modern equivalent (Laird Z131B-10).
Probably you will also need to recover the original oscillator, as it has an uncommon frequency (PAL: 28.37516 MHz, NTSC: 28.63636 MHz), but it seems to be available from some Chinese sources. You can also try replacing it with a DFO: this would actually be a nice upgrade, since with a properly-programmed one you should even be able to support both PAL and NTSC Agnus chips at the flick of a switch.
You can recover the original Video Hybrid, but you can also build a new one.
You will probably want to install all new components on this, for those that can be bought. Most passives should be easy to find, except maybe for the axial caps and EMI filters.
Apart from the above, the connectors are all on the market.
CPUs can be found second-hand cheaply. Every serious electronics shop should have all the 7400-series chips.
I think RAM chips cannot be bought new, but second-hand ones should be easy to find.
I would suggest using sockets for all ICs. Get new good-quality ones. 48-pin are hard to obtain, but you can easily replace them with two 24-pin side by side. Be careful with the RAM chips: if you socket them, they will probably be too tall for the keyboard to fit properly.
If you use the standard MSM6242B Real-Time Clock, you will need to calibrate the clock frequency through the TC9 variable cap, which requires the use of an oscilloscope. If you decide to recycle it from an old board, try not to move it during the desoldering. You'd better mark its original position with a marker before removing it. In alternative you can use an Epson RTC62421 or RTC72421. In this case, do not install Y9, C911, TC9.
If you are not interested in the Real-Time Clock at all, you can skip the following components: R911, R914, D911, D912, D913, C9, C911, C913, U9, BT9, Y9, TC9. You should also put a blob of solder on JP9 so that the system will pick up the one that might be present on a card inserted in the trapdoor slot (in this case you can also skip R916).
The battery holder is called BS-7 and is very easy to find. Other ones will probably fit just as nicely. Make sure to use a NON-rechargeable battery.
The solder jumpers should all be preset with the most common value, please refer to the relevant page for details. You will just need to take care of JP4 if you decide to install only 512k chip RAM: in this case DO NOT install U32 and put a blob of solder on all the three pads of both JP4A and B.
Good luck! ;)