Broken Archimedes, Working 3D printer

No post last week. I got busy with non “retro nerd” stuff and didn’t have anything to post.

So far this week has been a lot more exciting.

Poor Archie

My Archimedes 440 has decided that, no, it no longer wants to read Floppy Disk images. This has kept me occupied for most of the week, on again, off again. The symptom is every time you try and access the floppy drive (real or Gotek), there’s no motor activity, no drive lights and an error of :
Error from ADFS Filer
Drive Empty

Which is not great. After checking the obvious stuff (Make a real FDD image just in case, check files on the memory card have the right config file, check cable, check power, make sure the Gotek is powering itself up and allowing images to be shown) I got to the point where I knew I was going to have to disassemble the whole thing and break out the Logic Probe for further diagnosis.

This is a not insignificant undertaking as the Archie has a lot of different screw sizes mounted all over the system. It’s also awkward and heavy.

There were SO MANY screws in this.

I girded my loins (metaphorically) and got on with it. Now it was out of the case and laid out neatly on my workbench, I was able to get out the logic probe and “have a look” at the state of various lines. There were some obvious candidate places to look, but I stared with the FDD cable itself. Probing around the Gotek connector, there didn’t seem to be a whole lot of life. All the pins were being held either high, low or in one “special” case as floating. Turns out that was a “Not Connected” pin in the standard, so that’s OK I guess.

Right, no activity there. Let’s move further upstream. The next easiest chip to check was the FDC Chip, a VL1772-02 Floppy Drive Controller chip.
This is where things got interesting.

I ran across all the pins with the logic probe. There was definitely some data on some of the pins. Interestingly the place there didn’t seem to be any activity was on the output pin (Pin 22, WD) to the floppy. Could it be a bad FDC?

I checked the buffer inverter chip sitting between the floppy cable and the FDC chip. Each pair was suitably inverted from the input, so at least I could eliminate that.

I’ve ordered a replacement chip from Exxos UK as they have them for an extremely reasonable price. One of the forum members over on the Noel’s RetroLab Discord suggested them and OMG were they cheaper than any other source I was able to find. Exxos also has an excellent reputation, and I’ve been a member of the forums for quite some time.

Three Dee Printed Goodness

So the reason I discovered my Archimedes was unwell is I went to use it to fire up a new joystick interface I was building. This is a very simple interface with only a handful of diodes and a DB25 male connector, plus half of a Playstation extension cable.

A handful of diodes. My soldering has improved in leaps and bounds over the last few years.

I had got the bits together, soldered up and assembled in a shell when I looked at it and decided that the hole at the back was just too ugly to be allowed to live. The cable flopped around. This could not lead to good long term reliability.

When you have a 3D printer, everything looks like it needs to be printed in 3D 😀
This also gave me a chance to play with Fusion 360, a package I am learning slowly.

A few minutes using CorelDRAW to prep the primitive to convert in Fusion 360 into a model to import into the slicer software and I had a thing. Today I was also a lot more organised than I had been for my first print. I had good gloves, I had organised my workspace and I was comfortable prioritising what needed to be done and when it needed to be done by.
My prints got rinsed in a timely fashion and not for too long, cleanup was easier and overall everything was just so much smoother.

Oh boy does it show in the prints.

My first prints had an almost chalky feel to them. These are glossy, smooth and rock solid.

The finished product is just great!

That cable is not going anywhere
It’s a friction fit!

The Shape of Things to Come

I have a hot air rework station now. I plan to teach myself to hot air desolder over the next week. I will be practicing on some old “junk” motherboards, before moving onto finally decapping my Amiga 600.

Published by ilike8bits

I collect old computers and consoles

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: