Acorn Electron, restoration, repair, retrobrite & Arduino UEF Loader

 

Issue 2 Acorn Electron, restoration, retrobrite, repair and building my own version of a TZX Duino

 

This entry came about when my 8 year old (who is now known as apprentice-geek) asked if he could solder one of my TZX Duino PCB’s.

 

Inspired by the ZX81 board that I designed and populated, he asked if he could do one. It was a no brainer for me; he is showing great potential and has worked on two previous boards. First one was a comparator circuit which I use at work for soldering practice with students, he did a fantastic job so next up was to actually design a circuit board… so together we designed a noise-o-meter ;0) didn’t quite work as planned though as instead of making him quieter, he decided that it is great fun to get the LED’s glowing as brightly as he could!

 

When he asked if he could solder one of the circuit boards, I asked him which system would he like to make it for and offered the Dragon 32 (which was an amazing project for me) but he being a Nintendo person was a little concerned about Donkey King and the fact that it was definitely an unlicensed Donkey Kong clone so instead he opted for the Acorn Electron. Good choice apprentice-geek!

 

I did this restoration before I started this blog so only have a few photos of the process, but most of the information needed is there, I hope that you find my entry useful and interesting.

 

Acorn Electron Strip Down

 

 

This system was an ebay find, quite a good price and came with original software titles and more importantly a working power supply (they can be quite expensive to replace) It did have a couple of issues; an intermittent keyboard and a wee problem with the display but I will go into that later.

 

First things first, let’s have a look inside this beautiful machine

 

 

Remove the four highlighted screws with a medium sized crosshead screwdriver and place them somewhere safe (the Electron has screws of varying length so try and sort the screws in some kind of order)

Care should be taken when removing the top; the keyboard ribbon although looks quite sturdy can be easily torn so lift the lid from the back to the front to avoid any damage.

Isn’t that a beautiful sight, plenty of space to work with, everything easily removable… fantastic piece of electronic engineering!

The keyboard ribbon (highlighted) should be removed at this point; my only advice he is not to pull on the actual ribbon cable itself. Instead grip the ends of the connector and ‘wiggle it out’ (technical term ;0))

Now we have the Electron in two parts. I have to admit to being quite pleased with the condition of this wee Elk, everything was clean-ish inside, no real dust or grime inside it which is remarkable considering it’s age. Here is a close up of the main board

Time to start removing the circuit boards. There are four other connectors to remove; the loudspeaker, two a.c. connectors and a d.c. conector. First up the loudspeaker; note that the white wire is to the left although it will work if you reconnect it incorrectly. Pull up on the connector to remove it from the header pins and the loudspeaker will simply lift out.

After that, remove the a.c. connectors; again it does not really matter which way round these are connected. Simply pull up on the connectors to remove them.

 

Next remove the d.c. supply; this is a 3 pin connector (note that the red wire is closest to the bottom of the housing) It slides out to the right and I advise that you use the actual plastic connector to wiggle it out as pulling the wires could result in broken wires.

 

Now remove the four main board fixing screws (highlighted) with a medium sized cross head screwdriver.

 

Now remove the four main board fixing screws (highlighted) with a medium sized cross head screwdriver.

Once the mainboard has been removed, clean the dust away with a soft bristled paintbrush, use a toothbrush and isopropyl alcohol to clean the solder side, checking for any suspect solder joints afterwards. Then clean the component side with cotton buds and isopropyl alcohol. After cleaning, check the condition of the electrolytic capacitors for any leaks or bulging and replace as necessary.

 

Once that is done, remove the three fixing screws on the power supply PCB (highlighted) then repeat the cleaning and inspection process.

 

 

Now let’s have a look at that keyboard. Unscrew the five crosshead screws from the lid (highlighted); the keyboard should simply lift out after that.

 

Remove the individual keys; there are several ways to do this, either pull them off the keyboard with your fingers or you can carefully lever them off with a flat headed screwdriver. Alternatively, you can buy a specialised key removal tool and use that to remove them.

The spacebar is a little bit tricky as there is a metal clip which is a wee bit fiddly to remove; pull the spacebar up, then slide to one side, unclip the metal clip from one side then remove the key.

 

Let’s have a closer look at that keyboard

As you can see there is some flux residue on the highlighted solder joints; this particular keyboard was working intermittently with several keys. I cleaned the whole PCB using Mrs Geek's toothbrush and isopropyl alcohol, and then inspected the solder joints. They were still looking suspicious so I de-soldered, cleaned then re-soldered each joint in question. Below is a photo of the cleaned and re-soldered PCB.

We should now have all the parts disassembled for the retrobrite process; now it is time to clean them all. The process is exactly the same as the one shown in more detail in my last entry (Vic 20 (the 3 R’s) Basically, scrub each part with a toothbrush and washing liquid, rinse thoroughly then dry everything before the application of the 40% Cream Peroxide.

 

 

Lay clingfilm on a flat surface; overlap several strips until the clingfilm is about 60% wider on each edge of the part being retrobtited. Wear appropriate PPE (safety glasses ad gloves) then apply the cream peroxide with a paintbrush; try and get an even coat and care should be taken not to cover any labels on the part being retrobrited as this could result in blistering. I lucked out during this retrobriting (it was my first attempt at it) and thankfully didn’t damage the Acorn Electron label on the top panel. 

 

As I mentioned earlier, this was my first attempt at retrobriting; I had trouble when rotating/moving the keyboard components during the ‘baking’ process. A way round this problem is to lay the keyboard out on a flat surface (I use a glass chopping board) and that can be easily moved without disturbing the keys.

 

 

Now time to bake the parts in the sun; rotate each part 90 degrees every hour as well as massaging the cream peroxide on each surface. This will ensure that each side of each part gets an equal amount of sun as well as preventing the cream peroxide from dying out which could leave a streaky finish.

 

 After four to six hours in the sun take the parts in and wash and dry thoroughly. You dont want any cream peroxide left on any part of the case or keys. Pay particulat attention to screw holes and little noks and crannies.

after washing and drying with paper towel, I like to place the parts in the sun to evaporate what little water is left on the parts; this is especially important for the keys ans screw holes so lay them upside down and let the sun do its work.

Now it is time to reassemble the computer.

Starting with the keyboard, below is a photograph of the newly retrobrited keys

Before refitting the keys, give the aluminium base of the keyboard a clean; I find a soft paintbrush followed by a clean with isopropyl alcohol and cotton buds the best method for this process.

Refit the keys in their correct positions; the space bar is fiddly but if you reassemble it exactly in reverse to the way you dis-assembled it, you shouldn’t have too many problems.

 

Now lets refit the keyboard to the lid of the computer; simply screw the five cross head screws into their original position. And here we have a squeaky clean top part!

Lets rebuild the bottom half of the Electron

Refit the Power suppy with the three power supply crosshead screws

Then refit the mainboard with the four mainboard crosshead screws

Re-attach the power supply connectors; the grey a.c. wires simply push on to the two pins to the top right of the mainboard (it does not really matter which way round these go) the two wires will then fit into the groove on the plastic so that  they do not become trapped and crushed when the Electron is screwed together.

After that, slide the three pin d.c. connector on to the pins to the bottom right of the mainboard (note that the red wire should face towards the bottom of the Electron.

Now, fit and reconnect the loudspeaker. It easily slips into the slot on the top left of the case then attach the connector to the top left of the mainboard (note that the white wire should be on the left side)

 

Now refit the keyboard to the mainboard using the single in line socket (note this can be quite fiddly especially if the pins on the pinheader have bent out of shape during the removal of the connector) Also worth noting is the fact that the socket has some exposed connections facing down towards the mainboard which has to be insulated. There should be a sticky foam insulator which will stick on to the connector; if not simply use some insulating tape as shown below (I removed that afterwards and used the foam insulator)

Finally, screw the Electron together using the four crosshead fixing screws.

And here we have a restored Acorn Electron… looking beautiful!

Now lets turn our attention to the cassette input to the Electron; I do have some original tapes for this computer but age it appears to have caught up with them and they do not load reliably so after a bit of research; I found out that you can use a TZX Duino and load a version of the software which supports the Electron UEF format rom files. I did buy a TZX Duino kit from ebay and although it was a very good price and works flawlessly but I didn’t like the fact that components were on both the solder side and component side, so I designed my own version.

I laid out all the components on the component side, manufactured a prototype then sent my design away to JLPCB for manufacture. I got five double sided, plated through hole, solder masked ans silk screen printed PCB's delivered in around two weeks for under £10! Fantastic value!

You can download my design from my new Github site on

https://github.com/Alleged-Geek/TZX-Duino

There you will find a zip file which contains all the files that JLPCB need to manufacture the PCB; I have also included the Eagle sch and brd files should you wish to personalise them.

 

This is where my 8 year old stepped in to populate the circuit board; he wants to do a blog entry of his own to share his experiences with you all so you will have to be content with a photo of the completed PCB for the moment.

Great work Apprentice-Geek! he soldered every single component on his own (even noticing and repairing his own soldering errors by himself) I am so proud of him!

 

Now we just have to programme the Arduino Nano; as a wee side note, I found it difficult to get information about programming the nano with the correct firmware to allow the playing of the Electron UEF files. Even worse was when I finally found the correct firmware, I couldn’t get the games to load. This section will explain what you need to do to get things working.

 

I found a version of the firmware online which used the Arduino IDE software to programme the Arduino Nano. Now, I am quite experienced with the Arduino software having done many personal projects using this versatile microprocessor but try as I might; I couldn’t get the programme to load. I was experiencing library and screen errors so I gave up after a couple of hours. I then turned to the fantastic people on the Acorn/BBC forum

 https://stardot.org.uk/forums/

 

From there, and after searching through many posts, I found the following link

https://github.com/rickyelqasem/TZX_Tools

This piece of software allows you to programme the Arduino easily using drop down menus; I will now take you through that process.

 

I downloaded the latest version

 

TZX_Tools.v1.0.7.1.zip

Unzipped it then ran the programme

Now plug the Mini USB connector into the Arduino USB port, and the other end into your computer.

Find out which com port your computer has assigned the Arduino Nano to then set up the TZX tools with the correct firmware, logos and screen

After a wee bit of experimentation, I found that the following procedure works best as TZX Tools sometimes gets a wee bit confused after selecting all of the options.

Select your logo; As this PCB is going to be used on both my Acorn Electron and BBC, I opted to use the Acorn logo. Simply click on the logo icon then a dropdown menu appears, click and select the Acorn logo.

Next, click on the Com Port icon and select the correct com port; in this case it was com port 5.

Now select the correct Arduino board (this selection can vary depending on which version of the Arduino Nano you are using) This one happened to be the Nano V3 NEWBOOT but if the process doesn’t work for you press the reset logo and restart the process but this time select the Nano  V3 OLDBOOT.

 

We need to select the LCD screen used on your TZX PCB (my design uses a OLED 1306) but there are several other options which can be used depending on which type of TZX PCB you are using.

Now we need to select the correct firmware for the Acorn Electron; I found that the MaxDuino v1.67 TZX/TAP/UEF works flawlessly. Click on the firmware icon then select that version. You will probably notice that the Display icon greys out so we will have to re-load a couple of options before programming.

 

Now we need to re-select the Arduino Board, so again click on the Arduino Board icon then re-select whichever Arduino Nano version you are using (mine was the NEWBOOT)

We need to reselect the Display again, so click on the Display logo and select whichever screen display you have on your PCB (again mine was the OLED 1306)

Hopefully, the Upload icon will become active for you; simply click on that and TZX Tools will do the rest!

 

 

All going well, you will notice that an LED on the Arduino Nano board will be flashing as it is writing and after it has completed, you should see the following message on the screen of your computer.

 Below is the highlighted RX LED which should flash as the Arduino Nano is being written 

Now we need to get the UEF files working.

Another problem I found was that the rom pack I downloaded from the internet once unzipped didn’t work on the TZX Duino. This caused me some problems and a whole lot more searching on the internet. Thankfully and again thanks to the good folks at

https://stardot.org.uk/forums/

I found the solution, it appears that the files have to be run through another process before they are compatible with the TZX Duino.

It was rickyelqasem on Github to the rescue once again with another fantastic piece of software which allows you to bulk convert UEF files

You can find the software using this link

https://github.com/rickyelqasem/UEF-Extractor

If you google Acorn Electron Rom Set, you should be able to find a link to a site which will give you a zip file containing all (or most) of the games ever made for this classic computer. 

 

Here is a step by step procedure of how to extract the UEF files into a format which the TZX Duino will accept.

Firstly unzip and install the following file taken from the Github mentioned above

UEF Extractor 1.0.1(exe).zip

 

then you should have an icon like the onein the top right of the photo below.

 

 Now you will need to extract the zip file containing the original roms (I use WinRar which is free)

 

After that you will need to extract all of the individual zip files from the original zip file (basically, the original zipped up file contains individual zip files for each of the games)

Once they are unzipped, you should have UEF files but unfortunately, these will not work on the TZX Duino.

 

I am going to try and show you how I extracted a couple of versions of the classic Chuckie Egg for the Electron

Open up UEF Extractor

Click on the Extract UEF icon

Select the UEF files you wish to convert then click add; note you can bulk select the files. Then select the Target Folder (I used Extracted UEF) then OK

After that, format your SD/MicroSD card

Note: as the files are very small, you will manage to fit them on a small capacity SD Card; being an Aberdonian, I found that the best value ones were around the 8GB mark. They sould also be formatted using the FAT32 option (I also labelled the card as ACORN)

After that, simply copy and paste the extracted UEF files on to the SD card. After testing, I made individual letter folders for the SD Card then put the complete set of UEF files in the appropriate folders. Although this was a wee bit time consuming, it does make things easier to find the game you are looking for.

Finally we come to the last part of this blog: making the cassette loader cable. Finding information about this was relatively easy; all you really need is the pin configuration of the 7 Pin DIN plug. I have drawn what I hope is an easy to follow wiring diagram.

 

You will also need the following components

 

7 pin DIN Plug

3.5mm Stereo (or mono) jack plug

2.5mm Mono Jack plug

Stereo speaker cable (I used an old PS2 composite cable)

 

And all the relevant tools to solder the wires to the connectors

Here is my wiring diagram

Here is the wired 2.5mm Mono Jack Plug

Here is the wired 3.5mm Stereo Jack Plug

Here is the wired 7 Pin DIN Plug

And here is the completed cable

Time to test EVERYTHING!

Firstly, set up the Acorn Electron

Note that the TZX Duino will work with a mini USB Cable plugged directly into the Arduino Nano

Plug the 7 Pin DIN Plug into the Cassette port

Type 

 CHAIN""

Then press

RETURN

On the Electron

Now we need to select a file to load; as I put all the ROM Set on to my SD Card in alphabetical folders I have to do the following key presses on the TZX Duino (see Video)

 

Select the letter folder by pressing either the UP or DOWN buttons

 

Once you have found the correct folder press the PLAY button to enter that folder

 

Select the game in the folder by pressing either the UP or DOWN buttons

 

Finally press PLAY

 

And that should start loading the UEF

 

 Hopefully the UEF file will load correctly and you will be enjoying some 1980's Electron fun!

 Success! Another working machine!

Here is the Youtube Video of the whole process

The Acorn Electron is a fantastic piece of hardware; I loved every single  minute spent  working on it! It was also pleasing to introduce my 8 year old #Apprentice_Geek. His soldering skills have improved greatly since his first attempt…  Thank you my young apprentice!

Other people to thank are the very knowledgeable folks at

  https://stardot.org.uk/forums/

I don’t think that there is anything that they don’t know about Acorn computers!

 

Other thanks go out to rickyelqasem for the fantastic software he created

 

https://github.com/rickyelqasem/TZX_Tools

 

https://github.com/rickyelqasem/UEF-Extractor

And finally thanks to you for taking the time to read through this entry

I sincerely hope that this has helped you

 

If you have any questions or queries, please feel free to contact me by email

 

Alleged_geek@aol.com

 

My PCB design can be found on my new Github site by clicking on the following link

 

https://github.com/Alleged-Geek/TZX-Duino

Lastly, feedback is always welcome, please feel free to leave comments good or bad!