A week of leave, a week of retro goodness!

What a wonderful thing a week of leave is, especially if you have nothing planned, except your hobby.

I deliberately left myself plenty of time for just mucking around. I set myself three project goals, with some option “stretch” goals.

  1. Work out what was wrong with the floppy drive on the Archimedes.
  2. Decap the Amiga 600
  3. Print a 3D case for the Creativision Megacart


I got the Archimedes on the bench pretty much Friday evening and it stayed there for most of the week. The first thing to do was to completely strip it down to just the motherboard, the PSU and the CPU riser. That way I could have a look at what was going on with all the signalling.

I must put a big thank you to the StarDot forums, who, as always, were invaluable in their assistance.

Breaking out the logic probe and the schematics, there seemed to be 3 prime candidates that could be the cause of the fault.

  • IC47, a 1772-02 Floppy drive controller chip. This was a very commonly used chip for this era. Also used in the BBC systems among others.
  • IC38, a 74LS05 hex inverter. This is used as a simple inverter buffer. The prime candidate!
  • IC29, a 74HC574 flip flop. Not quite sure what this is doing, but it ties into several key drive pins.

I started with IC47, and initially I thought this was the most likely candidate. I could see data going in but no data coming out. Turns out I was looking at the wrong pin! Oh well, the spare I have ordered will be useful somewhere else I am sure šŸ˜€

This one was fine.

Next I moved onto IC38. Now these fail all the time, which is why I probably should have checked it first. The only reason I didn’t was a gut instinct. The logic probe showed this chip was happily inverting just as it was supposed to.

This one was also fine.

This left IC29. Now I don’t really understand how this chip is supposed to work, but simply looking at activity, I could see data coming in on the input side, but nothing coming out of the output side. Everything was locked. The Drive Select pins were all being driven continuously and the Motor pin wasn’t being driven at all. This could explain the lack of any activity.

Having a likely suspect, I carefully desoldered the chip, using my desoldering station to remove the majority of the solder, and my brand new hot air rework station to carefully loosen the remaining solder. Popping it out, I stuck it in my TL866 II+ and ran a logic analysis over the chip which promptly failed! That seems to vindicate my suspicions. Unfortunately it’s not a chip I can buy from any of the local suppliers, so I have one on order. In the meantime I’ve stuck a nice machined pin socket in there to make the next step easier when the part does arrive.

A machined pin socket, ready for the replacement chip.

Amiga 600 decap

The Amiga 600 still had 4 capacitors I’d been unable to remove due to the limited room around the remaining capacitors. All four were relatively “flush” up against an existing component. I had attempted to remove those components, without much success, so I was at the point where I needed newer tools, and finally I had a hot air rework station.

The four silver strips mid picture were where the capacitors were. The components above and below are soft plastic and are heat sensitive. I used lots of polyimide tape and aluminium foil at this point.
Two more horrible caps removed. Right up against that coil above.

As this was a new tool, I practiced on an old PC motherboard until I was comfortable with my work. I certainly managed to “pop” a capacitor that turned out to be through hole, not surface mount, but that board had loads of bent pins so I didn’t mourn it much. It did vindicate my basic approach. Slow air, 380 degrees for leaded solder, lots of polyimide tape and aluminium foil insulation around the temperature sensitive components near where you are working, and slowly slowly does it.

I gently heated the general area, trying to heat the board evenly as to not warp it, and at the same time raise the temperature of the components. Eventually they came free with only a light pressure on the tweezers I was using to gently lift the components with.

With this technique I was able to remove the remaining four capacitors. Replacements are on order. Soldering these components back in? That’s a problem for “Future me”. I suspect a delicate tip on the iron and, again, loads of polyimide tape and aluminium foil.

3D Case for the Megacart

This one was mostly me in front of a computer with OpenSCAD and lots of trying and trying again. The Madrigal Design forums had several people assisting here, with a BIG shout-out to Tom over there who managed to print a cartridge before I’d even had a chance to get mine on the print bed. It allowed me to rapidly iterate two new versions based on his feedback. I’m already contemplating yet another iteration, to add a way of securing things a little more robustly.

Once I had the designs in OpenSCAD, I was able to export as STL, then feed them to my slicer and begin printing.

These are a little too big for my resin printer, so I need to print one part on its shortest edge and another on it’s side. This means the prints take 8 hours and 5 hours respectively. If I had a bigger print bed I could print them directly on their faces, which would drop the print time down to much closer to under two hours.

(If it’s not obvious, the slowest part of printing with a resin printer is resetting the z axis. Anything that is larger in the z axis takes longer, so you usually try and align your models to be largest in the x and y axis)

The quality of the top was… OK. I think I need to get better at leaning my models. There’s some smearing that I think is improperly cleaned resin that rehardened.

Unfortunately the base failed completely. I need to review my print settings and reevaluate to see what went wrong. I don’t think it bonded properly to the print bed.

It emerges from the vat!
The top section. I think adding internal supports may help in future.


The moral of today’s episode seems to be – You don’t need additional tools until you do, and then you wonder how exactly you lived without them beforehand!

Now I have hot air, I think the next tool I will want to get will be a proper bench power supply with adjustable Amperage, Voltage and probably two voltages at once. That may be something for next year, though.

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 šŸ˜€
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.

Achievement Unlocked: 3D Printing

Over the last few weeks, I’ve been accumulating all the “bits and pieces” to finally properly use my 3D printer. Today everything came together and I finally printed my first 3d print!

Printer in action!

It’s a little holder for the rotary encoder and OLED display for a Gotek drive. I often mount them externally on some cable, so that it’s easier to access the buttons. This is particularly useful for things like the Archimedes where the Gotek faces the rear or the Amiga where it connects through the side. No more having to peer around to read the display šŸ™‚

It’s not perfect, but OMG it looks nicer than I expected!

Ignore the gap at the bottom. I have fixed that with a dab of superglue.

What would I do different? Probably some sort of clasp for the front and a bigger, more robust hole for the screws at the back. The Rotary encoder bit wasn’t quite right. Other than that, I’m very happy.

Total print time was 45 minutes for the base and 4 HOURS for the top.

I’ll release the SCAD files once I have made the corrections.

YouTube resources

AKA… All the cr@p I watch on YouTube related to retro computing…

I watch a LOT of YouTube channels, and I mean a LOT. Here’s a list of the retro or retro adjacent channels I watch.

EDIT: just to emphasise, this is not a definitive list, this is just the stuff *I* watch. There may be channels out there that I don’t know about. There may be channels that, for whatever reason, I won’t watch or can’t watch. This is just my list.

8-Bit Show And TellCommodore centric
Action RetroMacintosh centric
Adrian’s Digital Basement
Branchus CreationsMacintosh centric
bwackCommodore centric
Chuck Hutchins
Dan WoodMostly Amiga
Dr. Dave’s DiversionsMostly Amiga
ETA PRIMEEmulator centric
flashjazzcatAtari 8 bit centric
GadgetUK164 – Retro Gaming Repairs & Mods
Jan Beta
Joe’s Computer MuseumApple centric
Josh Malone
Least Significant Byte
leesmiths workshop
LGRPC centric
Mark Fixes Stuff
Mr Lurch’s ThingsAussie!
Ms Mad Lemon
NecrowarePC centric
Noel’s Retro Lab
Nostalgia Nerd
Nybbles and BytesCommodore centric
Retro Hack Shack
RETRO is the new black (Wolfgang Kierdorf)
RMC – The Cave
Tales of Weird Stuff
Tech Tangents
Technology ConnectionsNot strictly “retro” but related
The 8-Bit Guy
The Digital Orphanage
The Retro Shack
XYZ ConceptsAussie!

So if you’re looking for new retro content… šŸ˜€

Mini MicroBee update

I have the PC85 Microbee from the last post working now. Thanks to Ernest, who persevered in his assistance and identified a mistake in the ROM order, I was finally able to get a proper booting PC85B system. This allows double sized (16K – AKA 27128) ROMs and I’ve got a couple of additional games installed in “high” ROM spots above existing ROMs.

(The PC85 “core” (or top) board is the same between the A and B variants* so it’s a simple ROM swap to upgrade from one to the other)

From here on out, I’ll probably swap out the ROM that currently contains Viatel, as I have no use for that, and swap it for some additional games.

I am also beginning my research on how to make a clear acrylic case for this unit. I figure a nice transparent case will show off the beautiful innards of this system, and it is beautiful.

The purple is nail polish used to cover exposed copper. It’s as much part of the machine as anything else.

For anyone who is upgrading the PC85 from A to B, the ROMs need to go in the following sockets:

ROM NameIC Socket NĀ°Lower ROM PAK Upper ROM PAK
ROM EIC 25PAK1 (Help)PAK9 (Free)
ROM FIC 24PAK2 (Spreadsheet)Reserved
ROM GIC 23PAK3 (Graphics)Reserved
ROM HIC 22PAK4 (Viatel)PAK12 (Free)
ROM IIC 27PAK5 (Shell/Menu)PAK13 (Free)

*Just to be especially exciting, there’s a MB8328-2 model that could theoretically be in a PC85 that needs a mod to be upgraded to 16k ROMs. Thankfully mine is a MB8328-4 which doesn’t have this disadvantage

While I wait for orders to arrive

I’ve got various bits’n’pieces on their way from China, so I haven’t been quite as busy as I could have been. Not a lot of upgrades / repairs are in the pipeline anyway so I haven’t needed to fix stuff.

Having said that, my SE/30 needs to be broken down and the Digital board needs to be mailed to the Eastern States for a deep repair. I think some corrosion has crept under some of the chips. The Modem port is playing up and sound has stopped working. It’s just a matter of timing and $$$. I already know who I want to send it to…

I need to buy a hot air rework station so I can finish working on my Amiga 600, which is mostly decapped. Once that is done I’ll order some replacement caps and fix it up. I’ll also start getting it set up for a Hard Disk. I have a IDE to CF adapter ready to go, with several different cards to try.

I’ve been working on the PC 85 Microbee. I’m trying to upgrade it to the PC85B revision, but I still haven’t got it fully working. I do wonder if there’s still an issue with the socket that I replaced last time? I’ve also run out of 27128 ROMs, which is hilarious. I had so many.

4 dead. 1 unknown and 1 erasing in the UV eraser.

I upgraded my workshop PC with a ZIP Drive. Remember those? I ordered a SATA to IDE adapter as when I last looked at the motherboard, I could not locate an IDE header. I was installing everything when I moved the SCSI card in the system and discovered the IDE header underneath. But of course that was where it was.

Both of these work. Both of these are connected.

I built a curing container for curing models from my 3D resin printer. It’s made out of a bucket that I have lined with foil and UV LEDs. The process was complicated but the end result was excellent.
First up, I bonded foil to paper of an appropriate length. I got the length by wrapping the bucket in a piece if string to get a circumference. I then measured out the paper and foil to the same length as the piece of string. I bonded them together with workable fixative. The paper was Christmas wrapping. The foil was kitchen foil.
Once they were combined. I covered the inside of the bucket with more workable fixative. I cut out a disk of foil and glued it to the bottom of the bucket, then carefully glued the combined paper / foil to the sides of the bucket then trimmed it all down to fit. Once that was done, I attached a 5m strip of UV LEDs wrapped around the inside of the bucket. I soldered a 2.1mm jack to the end and drilled a hole in the side, then affixed it so I could plug in the power from the outside.

I’m happy with the outcome.

This is emitting so much UV, it’s completely saturating the picture.

Finally, my father lent me his original copy of Telengard. This was the first game I played on the C64, and I’ve also played it on the Apple II and the Atari 800. I figured it would be appropriate to play it on the Commodore PET.
This was complicated by the game being the second programme on that side of the tape, so I had to load the c64 version first šŸ™‚
For future reference, I had to forward to 254 on the counter to load the PET version.

This took about 5 minutes to load. It felt like 5 hours.
You see this screen a lot in Telengard. I could do an entire post about Telengard tactics.

There’s a top secret computer coming sooner or later. Can’t wait to unveil it, but I won’t talk more until it’s in my hot sweaty hands šŸ™‚

Not a lot of “Productivity”

So despite starting several projects, I only got on successful project achieves this past week.

Firstly, I received some ROMs to use with one of my Apple II clones, as it wasn’t received with them installed. Unfortunately the power supply has chosen now to fail so I’ll need to strip it and see what I can work out. Oddly, people on the Apple forums want me to rebuild the power supply rather than just sticking in a suitable Mean Well PSU. Why? It’s not an original power supply anyway. A Mean Well will be cheaper, cleaner, safer and more efficient. I may even just gut the existing PSU and drop the Mean Well directly inside the cage.

ROMs in situ

EDIT:It’s not the power supply. Every time I install the ROMs, the PSU trips. I’m using 2816s which should work just fine. Clearly there is more to be investigated.

It’s an Apple II+ clone of some sort. Don’t know much more than that.

Secondly, after a trip to Jaycar, I had the bits to build a USB to Atari 800xl power adapter. You need a beefy USB Power source, but it works well. I just followed the guide here on Wolfgang Kierdorf’s channel. I made up both ends rather than dissecting an existing USB cable. It came out quite well, and means I don’t need the huge brick on my desk when using the 800 any more.

It saves space.

Finally, I’d found a Geode based single board computer while looking for parts. My housemate had salvaged it and hadn’t found a use for it. I thought it would make for an excellent DOS / Windows 3.1 system. I made up a power connector, but unfortunately it was DOA. No matter what I tried, I couldn’t get it to even send out a synch signal.

It would make a great micro gaming box, if it actually worked.

It’s not a huge loss. My desire for a 486 class PC is not high, and there are some nifty alternatives if I wanted them.

So I was quite unwell this week…

So what did your kids get you for father’s day? Mine gave me a cold!

I had two days off work, and to be perfectly honest, I probably should have taken at least one more day off as well.

Despite being “Death warmed up”, a friend put me onto something that had been dropped into the “recycling” pile at a local Maker Space. I rugged up, drove out and came back with a boxed Genlock! Awesome!

Everything’s in there. Wish I had a working Amiga…

I did not move for the rest of the week šŸ˜€

However I was feeling well enough by Saturday to start a couple of projects, one of which wasn’t even RetroComputing related! Crazy, I know!

First up was a request from a friend of a friend to make a TV Stand for their flatscreen TV. It theoretically has standard VESA mount points, but with an 8Kg screen and a lot of potential leverage, I wanted to lean into the overengineering. I’ve made plenty of monitor stands for LCDs, which are often available practically for free if they don’t have a stand. I’ve got pretty good at it, but this was a whole new level.

I ended up leaning into the additional strengthening and I’m pretty happy with the result. I just hope the end recipient likes it.

Mounting fixtures there on the base.
There’s a LOT of glue in this construction.

Afterwards, it was time for me to work on another project. I’d ordered in a replacement PSU “gubbins” for the Amiga PSU I’d got that had a nasty habit of tripping the RCD. Rather than trying to diagnose, it’s a LOT easier just to gut n rebuild PSUs. Newer technology works more efficiently, is lighter and delivers much cleaner power.

It was easy work to extract the old “guts” from the brick and there was a LOT of space inside there for the new PSU. I didn’t trust the existing switch, so I went to Jaycar and bought a similar sized one with an integrated Neon illuminator. Makes it nice and easy to spot if it’s on or not.

The only problem I had is the PSU is so light I end up nearly throwing it across the room.

So much smaller.

Today I spent a bit of time working on more of the Amiga 600. My desoldering station appears to have a problem, and I think I’ve identified where it is, but for now I have no desoldering capabilities other than hand pumps. I was able to desolder the RF converter, but I was unable to get the keyboard connector or the choke out. This means I have only been able to get most of the SMD capacitors out, not all of them.

Only 4 more SMD caps to go.

I used a new technique, involving two soldering irons, that works quite well. You basically heat the cap from both sides at once, and the caps just pop cleanly off with no force required. It’s really gentle on the pads. I always apply extra flux, of course, but so much gentler than any technique I have used or seen, short of hot air.
(I am fairly sure I first saw this over on GadgetUK164’s YouTube channel.)

A bit of braid afterwards and the board came up as new.

It’s so nice!

To do this I needed to get a second soldering iron up and working. A good friend had gifted a TS-100 soldering iron, but I’d had no end of troubles with it. I thought this was a good time to revisit it. I knew that one of the problems was the tip wasn’t fitted properly, but the included allen key was useless, and I couldn’t remove the screw holding the tip in.

I attacked it with my generic “giant box-o-screwdriver tips”, which has most of the common “bits” to open up stuff the manufacturer doesn’t necessarily want you you to. Thankfully, one of the imperial allen tips was a perfect fit, and I was able to refit the tip and replace the screw in short order.

I also updated the firmware. The first time I’d tried this it hadn’t worked, but this time it went on without a hitch. No idea what is different.

Finally I made a stand for it out of some coathanger and a bit of old Ikea bracket designed to hold bookshelves to walls.

TS100 in stand above all the SMD Capacitors I have removed so far.

For now, the A600 will go back in the project box until I can afford a hot air rework station.

A Weekend Off

In my best Swedish Chef Voice – “Ooh Three Dee! THREE DEE!”

I decided not to push things this weekend. I had some “job” related stuff this weekend so I wanted to take it easy.

I still managed to get in some small project work.

First project I worked on was I’m trying to set up a project to use an Arduino as a translator between Megadrive/Genesis controllers and “Atari” compatible systems like the C64, the Amiga and, of course, the Atari systems. I’ve made up some connectors and tried my hand at a first attempt, which unfortunately did not work. Thankfully some clever people on the Artifactory Slack were able to point me to a solution that I can use involving OptoIsolators, so I have some of those on order.

One day this will work. Once I have the basics working, I can add autofire, stepping mode and the like.

Secondly I set up the 3D Printer that I recently received from my wife. It’s an Anycubic Photon Zero, and setup was remarkably easy. I need to set up myself with some “extra” bits and pieces, such as a decent mask and some extra Isopropyl, but I did manage a basic test print. Next week, time and budget willing, I will actually print something emulation related. I’ve designed a little “carrier” to hold a rotary encoder and an OLED screen. Should be pretty sweet if I can get it working.

This is two parts that screw together to keep it simple.

Next I made a modification to the cable I made for the Microbee. It now has an on/off switch, a power LED and some big diodes to drop the voltage down a few notches to keep the main system cooler.

Have I mentioned how much I love my Microbee computers? It’s a LOT!

Finally I went back to my old house and went through the shed. I knew there was an Amiga power brick in there, and figured I could use it with my A600. When I got in there I found a whole bunch of other “bits and pieces” including two SCSI CD Roms, 4 SCS HDDs (1 in SCA, 2 in 68 pin and 1 in 50 pin), two floppy drives, two ZIP disk and some assorted cards that seemed useful. Nice!

No idea if any of these work.

Oh, during the week I also started the long slog of decapping my Amiga 600. Unfortunately I hit a bit of a roadblock insomuch as I don’t seem to be able to remove the caps without hot air. I’ll give it another try next weekend, but I suspect it’ll have to wait for Christmas and a Hot air rework station.

So not too slack, but not my usual load.

Happy Father’s Day to everyone who celebrates.

Being the Microbee

I got the PC85 Microbee working šŸ˜€

First up, I am, once again in debt to the Retro Communities to which I belong. The people over at both Microbee Technologies and MSPP (Especially Brad) who provided advice, pointers and general assistance as I got the second of my Microbees working.

Now, the fault I was seeing was instability on boot. There seemed to be an issue where some times the ‘bee would boot into the wrong mode. Most times it would boot into the Menu. Sometimes into BASIC. Sometimes into WordBee. Sometimes it would just “hang” in a strange corrupted mode. The Menu was also only showing two items, not the half dozen it should be showing.

Once it was in BASIC, I could happily boot games and run them without a hitch. I was confused. Usually if a system was unstable, it would crash randomly. This meant it was something very specific that was only involved in choosing which ROM to boot from.

I started troubleshooting things, firstly by reading in the ROM images and comparing them to “known” images. All the ROMS came up clean. (There was a brief detour when I thought the Menu ROM was bad, but this turned out to be not the case. There’s two versions of that motherboard and I was looking at the wrong set of ROMs)

I then cleaned all the pins on all the ROMs. The socket the Menu ROM sat in was green with battery corrosion so I removed it and replaced it with a Machined Pin socket. This improved reliability somewhat, as now the system tended to boot into the Menu.

Around this point I removed the connectors completely between the base board and the core board to see if that helped. The system seemed no better.

I also discovered there was a diode in the area that was growing green inside its tiny glass tube. That came out and was replaced, but I was still unable to boot reliably.

At this point I put it away for a few days.

Brad over at MSPP started asking some leading questions about symptoms, and, based on my replies, was able to narrow the likely fault down to a handful of chips, most likely IC26, a 74LS74. He suggested that if the system was stable without the D ROM (and it was) then the problem was with the control logic, and IC26 was the one closest to the corrosion.

To test this, I dug out my logic probe and started checking logic states on the IC. I could see logic states coming in on the inputs (High, Low or Pulsing) but the outputs were just showing as floating. This was highly suspicious behavior, so I zipped down to my local Jaycar (I’m not sponsored. They’re just conveniently close) and purchased another Machined Pin socket and a replacement 74LS74.

Removing the 74LS74 was not easy. It really didn’t want to come out. While I could clear one row of pins, the second row just didn’t want to play at all. I tried all sorts of tricks. Extra solder, wicking solder away from the top. Extra flux. Resoldering. they just wouldn’t budge.

In the end I was worried I’d start damaging pads, so I cut the legs free of the chip and was able to remove the legs with a normal soldering iron. Even with this, I’d lifted one pad and damaged a second. Thankfully this was an easy repair, but still. I cleaned up the pads with braid and attached the new socket.

Off come the legs…

I dropped in the new 74LS74 and checked the logic again. I could see “sane” logic on the outputs, so that was an excellent sign. In went the D ROM and… it booted without a hitch. More importantly, my Menu was now showing all the options. Ooh!


I spent the next few minutes testing as many options as I could, including the Self Test. Everything just ran. The self test also confirmed that the keyboard was fine.

While I had everything open, I also put a proper heatsink on the 5v regulator, for longer life. Next time I go to Jaycar, I’ll probably build a little circuit with a diode inline and a switch, to drop the voltage from 12v to 10.8v, to take some load off the regulators.

Yes, that’s grey “CPU heatsink” paste. Couldn’t find my standard white paste. Eh. It works.

My final step will be to make a nice clear acrylic case for it. Something so you can see all the internal “gubbins”.