jckarter

everyone already knows i'm a dog

the swift programming language is my fault to some degree. mostly here to see dogs, shitpost, fix old computers, and/or talk about math and weird computer programming things. for effortposts check the #longpost pinned tag. asks are open.


email
mailto:joe@duriansoftware.com

jckarter
@jckarter

It took a few years, but I finally found one! This was the only "laptop" model of the FM TOWNS that Fujitsu ever made, and it was only available to schools. The CD-ROM doesn't appear to work, the screen is dodgy, and it almost definitely needs to be recapped, but it even mostly appears to work besides that.

(for more teardown and repair pics, the current end of the thread is here)


jckarter
@jckarter

This boy's definitely a chonker, and if anything looks bigger in person; it easily ways at least 10 pounds. Here's a picture with a 15" Titanium Powerbook (itself pretty big by today's standards) for comparison. Despite the "laptop" form factor, there's no battery; the internal power supply takes mains power in directly from a figure-eight connector on the left side. On the right, doors open to expose two PC card slots and the hard drive bay. The 2.5" SCSI hard drive pulls out easily in a little caddy. There's also two ports for external gamepads or mouses as well as audio in and out ports.


jckarter
@jckarter

A door on the back covers up more of the ports; inside, starting from the top left, there's the reset button, an external keyboard connector, and S-Video, composite, and a 15-pin RGB connector. (I don't know whether it's VGA compatible or not; other FM TOWNS computers use a PC-98 style DB15 connector with its own pinout.) By some miracle, this FM TOWNS SN actually has a video capture expansion card in the expansion slot below it, with S-Video and composite video inputs. On the bottom row, there's a switch which controls whether the little nub controller behaves like a mouse or a game pad, a 25-pin RS-232 port, a 50-pin SCSI port, and a parallel port.

The CD-ROM is interesting because it has what seems to be a mechanical opening latch, rather than the door motor being controlled electronically. You can release the tray even while the computer is turned off, and it springs open.

On the bottom, another little door gives access to the RAM expansion slot. I got this computer with a 32MB SIMM in the slot, giving 36 MB total RAM.


jckarter
@jckarter

I pulled out the video input card in preparation for taking apart the computer itself. It uses a totally different form factor from the video cards for FM TOWNS desktops and has a double-decker layout.


jckarter
@jckarter

Even though this FM TOWNS SN is in great cosmetic shape, and mostly works, there are definite issues that need addressing—something is wrong with the video output causing rolling black bars on the LCD output, and the CMOS battery is dead, meaning the system has lost its hard drive configuration and won't access the contents of the drive even if the drive itself is working—and even if capacitor plague hasn't yet killed it, it's only a matter of time, so I need to get a look inside. First step is to remove the eight bolts from the bottom of the computer, though we'll be taking it apart from the top down.

Flipping the computer back over, with those fasteners loose, the first part to come free is the back plastic cover behind the display. Removing it reveals part of why this thing is so heavy—everything is mounted inside a thick steel frame. There might be a more convenient order in which to take things apart, but my next step was to disconnect and remove the display. With the expansion card removed, and the two ground clips undone, there's just enough room to work the four connectors from the logic board to the display (two on each side) free with spudgers. The display hinges are held to the frame with three screws on each side; with the hinge screws removed and the connectors released, the display lifts off the top, revealing the keyboard bezel, which comes off with two screws on the sides.


jckarter
@jckarter

Removing the keyboard bezel revealed one capacitor that had already corroded off the board and was stuck between the plastic shell and steel frame. The keyboard itself has one small screw holding it to the frame below the ALT key, as well as two ribbon cables connecting it to the logic board from the back end. Removing these allows the keyboard to come away from the frame. The pointer is separately mounted to the top of the frame, and we don't need to detach it to disassemble the frame, but we do need to release the two ribbon cables connecting it to the logic board underneath.


jckarter
@jckarter

The final thing attached to the top frame is the shielding cage holding the video output board and status LEDs. This is a separate block of steel that's mounted to the back of the outer frame with four screws (and the mounting nuts for the S-Video and VGA connectors), and on the other side by two screws hidden below the status LED board. The LED board comes off by removing its two screws and releasing its ribbon cable, giving access to the shielding cage's mounting screws below it. The video board itself has a ribbon cable to release as well, which threads through a slot in the top frame. After disconnecting these cables and removing these screws, the cage can be lifted out of the computer with the video output board inside it.


jckarter
@jckarter

Removing the video output board revealed a spot on the logic board where what turns out to be a second electrolytic capacitor had already fallen off and gone loose. To reveal the rest of the logic board and the drives and power supply below, the top plate of the frame comes off after removing 13 screws, six along each side as well as one recessed in the center. Now we have access to another daughter card with the keyboard and gamepad connectors, the hard drive bay, the floppy drive, the power supply, and the CD-ROM drive. From the center, we can simply remove the riser for the expansion card for safekeeping.


jckarter
@jckarter

From here, removing the remaining components from the motherboard is fairly straightforward. The CD-ROM drive is connected by a ribbon cable and two-pin JST connector near the back, and mounted using four obvious screws around the cage. With it removed, check out the big spring arm that holds the entire drive mechanism as it gets mechanically ejected or pushed in.


jckarter
@jckarter

The floppy drive is connected by a single ribbon cable. The keyboard/gamepad daughter card has two ribbon cables, and is held to the frame only by the mounting screws for the keyboard connector on the back and the two gamepad connectors on the side. The reset button cap pulls off the button stem to make angling the board out of the case a little easier. With these two components removed, most of the components on the top side of the logic board are now visible, including most of the electrolytic capacitors, such as the one that had already popped off. Luckily there doesn't appear to be too much secondary damage from electrolyte leakage around here yet; there's some corrosion on the legs of the AK4510-VS IC in the bottom left corner of the last image, but I've seen worse on vintage Mac boards that survived🤞🏻


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