… and even more obviously, everybody needs a second recap in their quarantined life. After the recap of my A3640 went surprisingly well, and even ripped off pads were replaced and reconnected, I felt confident enough to do a board that’s a little bit bigger and a little bit more involved than that poor little 040 accelerator: My Amiga 4000.

As my Amiga 3640 processor card, the Amiga 4000D board was previously recapped in a job that replaced the SMD capacitors with their through-hole siblings.

I know, I know, another recap story, REALLY? Haven’t we heard enough of that already? Let’s just twist the caps off, the recap trolls on Facebook will tell you. Come on, folks. You are lucky enough to have the chance to operate some 30 plus year old machinery. Think about it for a second. What else that you have today will still be good in thirty years from now? Your iPhone or Android phone? Certainly not. Your MacBook? Your Chromebook? This stuff is going to be in the landfill and long forgotten in much less time. So PLEASE, treat these machines carefully. They are witnesses of a very different time, when reality consisted of the cold war and 1200 baud modems. If you have doubt about what to do, let someone help you. There is a friendly community of folks keeping these machines alive. And if you want to do it yourself, practice with something else first. Something that is ok to break. I heard there are a lot of cheap Ataris out there (just kidding!!)

It’s not visible in the picture, but many of the legs of these caps were not attached to the board anymore

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A few days ago I did some temperature measurements with my zz9000 graphics card from MNT GmbH in Germany, which turned out to be surprisingly hot. It started out as a test of the CPU temperature of my freshly overclocked MC68060RC50 (rev6) running at 100MHz, when I noticed that the graphics card seemed to run hotter than the CPU.

Particularly the FPGA and the two capacitors C154 and C155 were transforming a lot of electricity into hot air.

A cheap IR temperature tool is super useful

One day later, after installing Linux/m68k from scratch over night, the Amiga 4000 didn’t boot anymore. Of course I thought that I killed the CPU. 100% overclocking can’t be good, right?

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What happens to long lived electrical engineers? They diode!

I have had trouble with the Amiga 4000’s serial port since I got the machine. At first I got a few bytes through every now and then, but it was pretty much unusable, even at 9600 bps.

When “learning online” about all the magic of open source in GitHub, I stubbled about Keir Fraser’s Amiga Test Kit, John Hertell’s DiagROM and SukkoPera’s Parallel / Serial port tester for the two.

Of course it’s not worth just ordering a single one of anything in the electronics world, and so I ended up joining the market of dongle builders. If you need one, let me know.

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My keyboard is missing a key. There’s no escape!

Well actually it wasn’t escape that was broken on my nice click-a-dee-clack Amiga 4000 keyboard, but CAPS LOCK! And bit even the key itself, it was the LED that just wouldn’t show the status. No problem, let’s take it apart

So many screws!

At first I thought the LED might have died after my recent diode intermezzo on the Amiga board. But measuring with my multimeter I see that the LED is just not getting any power. Let’s look at the membrane.

It seems I forgot the before picture

There was a piece of the trace missing. It seems it had corroded away. The previous owner probably spilled Coke on it. My first approach was to scratch the green cover of the existing trace so I can connect to it.

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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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