ZX Spectrum Reparatie en Jet Pac! (dutch)
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ZX Spectrum Reparatie en Jet Pac! (dutch)

August 15, 2019


Hi, welcome to my YouTube channel. About 11 months ago I received this ZX Spectrum as a birthday present. from my twin brother. I was and still am very grateful. However, it turned out to be broken. I dedicated two videos to it, which you can find on my channel. In the second video I concluded that the ULA chip is defective. Those are no longer being sold. There are some projects which attempt to recreate or replace it with modern technology, but those cost at least €30 So I’ve been on the lookout for a parts unit, which I’ve found. Here it is: As you can see, the top keyboard layer is missing. The keyboard membrane itself has also been ripped. This is quite common as the membranes tend to become very fragile. But you can still buy those membranes new. If necessary, I might consider that option for my own ZX Spectrum. But first I would like to try salvaging the ULA chip from this unit. I can then verify if it still works. The ULA chip is located here: So I will pull that chip and install it into my own ZX Spectrum. Then I will know whether I’ve got a working unit again. The ULA is the only chip that is socketed. This is convenient as I can just pull it out. No de-soldering required. So I will try prying it out with some tweezers…. And it just comes out without any issues. I will now remove the screws from this one, so I can install the chip. I would prefer not to take it apart entirely, as that would require removing the ribbon cable, which is risky since it wears out very easily. There is one here and another one over there. Repeatedly removing and reinstalling breaks those cables. Previously I took out the ULA chip without removing the cables, and now I can just slip the new chip in. Unfortunately not a very spectacular view on camera, oh well. I prioritize trying to keep my ZX Spectrum in tact. So, I’ll leave it like that for now. Quite easy really. Done. I will now attach a power supply and test if it works. For now I can test it without attaching a monitor, as I’ve shown in the previous video already. Because a defective ULA chip causes the sound not to work. You can test the sound using the ‘beep’ command. So we type: beep, 1, comma, 2. And we can hear that it now works, which is nice. An easier test: whenever you hit a key, it makes a little ‘tick’ sound. Holding a key down makes it repeat, so you hear a the repetitive keystrokes. I did notice some of the keys did not register, but now it seems to work fine. So I’m afraid the membrane is dying in my unit too. But for now let’s attach a monitor, try loading a game and see if it all works properly. Here we go! That looks good: “1982 Sinclair Research”. Fantastic. All appears to work fine. I will now write an incredible BASIC-program… One we’ve all written at some point… This is a great opportunity to take a look at the weird but smart keyboard layout of the ZX Spectrum. Currently I need the “print” command, which is located right here on the “P”-key. All letters on the keyboard are linked to different functions. You can also see that my cursor is a flickering “K”, which means “keyword”. So, if I now type “P”, I get the “print”-command. And now the cursor has changed into an “L”, I assume meaning “letter”. I now need a quotation mark, which is located on the same key. Kinda neat, “print” and ” on the same key. I can now write out my name… B…a….r…t….and finally another quotation mark. Enter. And now… 20… “Goto” (which is on the “G”-key)… 10. Enter, and finally: Run. Oops, my mistake. I only need to press “R” to get the run command. So, It just printed my name 50 times. It now asks “scroll?”. We just hit Enter… and it scrolls down even further. It proceeds to ask “scroll?”again. As if to say: “Are you bored yet?” Hitting any key will make it scroll further, except when you press “N”, which will return us to the program list. As I explained, most keys have secondary functions. Take a look at the “B”… There is the normal “B”, “*”, the “border”-command, the “bright”-command, and finally the “bin”-command. So there are 5 functions assigned to one key. But how do I get to all these functions? When I am in keyword-mode (flickering “K”), pressing “B” will give me the “border”-command. Because that is written in white on the key. If I want to write the “bright”-command, I hold down this shift button, hit “caps shift”, and then type “B” to get “bright”. If I want to write “*”, I just do this…. (hitting “B” whilst holding down the shift key) Finally, If I want to write “bin”, I hold down shift, hit “caps shift”, let go of the keys, and then push the “B”-key. This may seem rather inefficient, because to get “bin” you need to do so many different actions. But these rubber keys do not allow for easy typing, so that makes the commands more efficient. All the commands you could possibly need are already written on the keyboard, which I’ve always found very useful. You can just look around to find the command you need in case you forgot its location. When it’s not written anywhere, it simply doesn’t exist. A nice reminder. It’s currently one week later. Originally I wanted to load a game in this part of the video. Unfortunately, it appears the membrane is finally dead. This row of keys doesn’t register at all anymore. I really need the “P”-key for typing Load”” So, I ordered a new membrane online. Here it is: A new keyboard membrane. It came from Spain. Costs about €15. I will install it. Hopefully I can then finally play a game. I don’t know how often you guys want to watch me open a ZX Spectrum, but I hope this will be the last time. Let’s have a look. Here we see some metal tabs. They are part of the metal top layer and folded over. We need to fold them back. There should also be some glue, but other than that this should allow us to remove the metal cover, and then the rubber keymat. Then we reach the naked membrane. That’s all. Here we have the rubber keys. And here’s the membrane: We take this one out… And we install this one. This repair is quite simple as you can tell. We put the keys back, and now we need to re-attach the metal cover. And that’s all there is to it. Very simple. We reinstall the ribbon cables. And we now close up the ZX Spectrum, hopefully this is the last time. Let’s play a game. I’ve attached the ZX Spectrum to my PC through an Easy Capture device, So I can now display the video from the Spectrum on my monitor. On my tablet I have installed the “PlayZX” app, which allows me to load old games using the headphone output, which is connected to the “ear”-input on the ZX Spectrum. I have also attached a new accessory: a joystick interface. The ZX Spectrum doesn’t have internal joystick ports so you had to buy a special interface. And that gave you a single joystick port. Two-port versions also exist, but I bought a singular one. The game we’ll load is called “Jet Pac”. I still remember it from the past. Which is why I chose it. You can play it with either the keyboard or the joystick, but I prefer the joystick. Loading takes a while, but I’ll speed it up. Here are some loading graphics. Back in the day we found this very impressive. The game has loaded, we are now in the menu. Using the numeric keys I can select the number of players as well as between keyboard and “kempston joystick”. If I recall correctly, my joystick interface is indeed compatible with “kempston joystick” So here we go. Push 5 to play the game. Let’s see if I can beat the first level to show how it works. I can travel up and down using the jetpack… The objective is to collect parts for the rocket. The parts are scattered around, so acquiring them isn’t so hard. And then I still need to fuel the rocket… So I need to collect fuel cells. And bring those back to the rocket. Apparently I still need to collect other items as well. I have no idea what it’s all for. Whoops. It’s actually quite tricky. And not very well playable. Sometimes you hit the bottom of those platforms even though you think you can move past them. So play-ability leaves some things to be desired. But back in the day we did not complain, we just played whatever we could get our hands on. Again, I thought I could move right there but then you push the button and nothing happens. Here for example. Why can’t I move up!? Now I can. One more fuel cell to go. And now we depart! That’s level 1. And here’s level two. Any guesses as to what will happen next? Look. New enemies. Again, we need to collect fuel. Game over. We’ve reached the end of this video. I am glad my ZX Spectrum has been restored to full glory. New keyboard membrane, and of course the new ULA chip. And I have finally been able to test this joystick interface, since I’ve had it for several months now. I just didn’t have an opportunity to test it. If you haven’t already, please subscribe to my channel. Till next… no wait. Thank you for watching, and till next time!

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  1. Ohhh de ex sinclair, is van 1983 geleden dat ik hem voor het eerst zag liggen in een etalage. Heb me kort daarna een commodore aangeschaft en vervolgens een philips MSX 1 welke ik nog steeds heb. Wat me bij de vraag brengt, wat zou je nog kunnen doen met een MSX?

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