¡Una hija para mi Amiga!

2020-08-16 Stefan 1 Comment

The heat wave has hit Mountain View these last few days and caused a power outage for the better part of the weekend, so between 40C/105F and no electricity to power a soldering iron we enjoyed mango ice instead of working on all the projects.

Delicious mango shaved ice and jelly noodle shaved ice from Meet Fresh

None the less, after laborious project cat Katze (カツ) dropped all static charges to climb into a box and help me unpack my latest Digikey order, I couldn’t just sit around.

Katze survived. Even though we all looked.

A while ago I ordered one of Edu Arana’s A4000DB daughter boards at amigastore.eu. These are an easy way to lower the temperature in the already hot Amiga 4000D case and the power consumption a little bit. Plus, as Guillaume pointed out, I’m an arananet fan boy.

The first cut is the deepest!

2020-08-11 Stefan No Comments

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?

Fake flash!

2020-08-09 Stefan 2 Comments

I’ve heard of the whole Chinese relabeling industry, but in the past I have always been lucky with my eBay purchases. Until this last time.

Harmless looking and the correct part on the picture

I kept ordering a number of times from the same folks on eBay, but it seems that they ran out of genuine AMD 27C400-120s and decided to ship relabeled Toshiba -150 parts instead.

My “Made in Germany” fiber glass pen to the rescue

A tale of two diodes…

2020-08-09 Stefan No Comments

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.

Keyboard fun!

2020-07-29 Stefan No Comments

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

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.

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.

Just a small upgrade

2020-07-28 Stefan No Comments

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

Recap of a revised recap

2020-07-26 Stefan 3 Comments

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.

I’m back.

2020-07-25 Stefan No Comments

It has been 10 years since I have moved to the US and therefore had left all my Amiga gear behind. “I can always run UAE” I thought. But some goodbyes are harder than others, and some are not forever. So here I am, proud owner of an Amiga 4000 again.