… When I have been playing my overclocking games, I was sourcing a lot of oscillators from eBay. One thing I noticed was that there are a lot more choices for modern SMD oscillators than for the old DIP14 tin cans. As a matter of fact, I found 50 and 100MHz oscillators in all sizes quite easily, but what if you want to go up gradually, say 105 or 108 MHz? Maybe I looked in the wrong places, but I was out of luck.

A solution had to be found, and that was to put a rock under the clock to make it fit. And of course I was just looking for a project simple enough to try and build something with KiCad.

The rock: oscillator adapter board

Being a hardware developer in 2020 is almost as easy as being a software developer in 1980. You basically need a computer and a lot of patience.  Once my KiCad design was done, the first version was quickly uploaded to OSHPARK. This place is fabulous. Want to try some hardware really quickly? Get three boards of decent build quality and great looks for two bucks in the mail, with no delivery fees. It’s almost paradise.

The order process is simple and small design are not discouraged by 15 dollar delivery fees

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Lots of things happening at work, so it’s good to do a little meditation by soldering in the evening. Guillaume sent me a Greaseweazle kit but the STM32 still looks like the next level of soldering to me. It makes 0805 components look large. I’m missing a 74F257 that was lost in the mail, so the 060 adapter has to wait for a while. But there are other ways to treat an A3640 rev 3.1.

First, a socket for the oscillator will make it easier to test a little overclocking.

The 68040@25MHz worked nicely with a 60MHz oscillator, pushing it up to 30MHz.

Since the A3640 provides the clock for the Amiga mainboard, the chipset and memory will get a tad faster, too. This hack is super easy and will cost you 2 bucks for a socket and an oscillator.

The next and a little more involved one is an upgrade of the v3.1 card to v3.2. Gladly this is a simple GAL update, but unfortunately the GALs are not socketed. This leads to a brief intermezzo with my favorite tool ever, the hot air rework station.

The kapton tape job was a bit sloppy and over eager

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When I got my A4000 late last year, I could not have been a happier kid. I fleas surprised to get it for a fabulous price and it arrived just in time before the holidays.

The A3640 was a good first victim. Notice the through hole caps that ripped off the pads

That joy lasted until I noticed that there was no mouse, a Super Buster r6 (WTH) and a semi-professionally done replacement of all the capacitors on the board. Unfortunately through hole caps were used in the recap process.

You will find enough discussion about this on the internet, and people will suggest all sorts of craziness, like twisting off old caps or putting through hole caps on SMD pads. These are all terrible ideas. Don’t do it. If you have an Amiga (or any 30yr old computer), do it right or pay somebody to do it right. Recap services are not expensive and are definitely worth it.

One of the tricky parts is that the silk screen on the A3640 is incorrectly showing the direction of three capacitors. Make sure to consult the schematics.

Ruined! It is ruined! Or is it?

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