ZX Spectrum Part 1 - It's a very sick machine (and a BBC Micro update) 

Hi, I'm the author of the diagnostics you're using in this video :) You're right - when all 8 upper RAM chips fail like that, it's best to suspect other issues, like the 74LS157 multiplexers. The bright white lines down the screen are different though, as video memory is in the lower 16K. I'd actually suspect that the ULA in the machine might possibly be faulty, although it's worth pulling and reseating it just to make sure corroded contacts aren't causing any problems. One thing I will say - capacitor health is critical in a Spectrum, as if they've dried up you'll start getting all sorts of fluctuations on the -5v and 12v lines that feed the lower RAM. Change them out and see where you are - I recommend Vishay caps as you can get them in axial footprint and they are quite close in appearance to the originals. Nice spot on the Issue 2 schematics also - Sinclair got the RAS and CAS signals mixed up, and as you've noted, are corrected in future schematics. I'd love to see this fixed - with a new membrane and faceplate this will look like brand new :)

(Found your video in Jan 2020). Here in New Zealand at the time electronics goods were very expensive, paying an extra 110% or 130% duty tax, after import costs. So in 1983/84 That made the Commodore 64 cost $995 plus you had to pay extra for their own dedicated cassette tape unit. The Sinclair ZX Spectrum (could use any normal audio cassette unit) was sold here in either 16k or 48k version at various electrical shops. I bought the 48k version which cost NZ $ 699 at the time. As they were imported from the UK they output the Pal TV signal on the UHF band. However in NZ at the time ALL of our broadcast TV stations were VHF so almost no home TVs had UHF available. Therefore the importing agency here in NZ opened up the cases and did a (sorta "factory") modification so that Spectrums sold in NZ output in VHF. At the same time, the authorised importing agents also removed the power supply that came included in the original carton, installed a NZ type mains plug on it (we are also 240 volt) and then sold the power supply as an essential "extra" for another $29.95 . When I bought my computer I also paid retail price (about $25 each) for 2 games, a BASIC Star Trek game and "Nightflight" an airplane simulator. Later amongst friends and a club which operated out of the university, I was able to obtain about another 150 programs as, um, cough cough, "back-up copies" ! Note that the Spectrum 48 k had more USABLE memory than the so called "Commodore 64". Spectrum reserved 7k for screen display and had 41 k available. The Commodore counted their 64 k as a gross figure and it actually had about 37k actually useable available...I remember being told at the time. I had some friends take their Spectrum into their office, (an apprentice training school), and use it to do stuff that their Apple 2e computer couldn't do. Spectrum programmers did fantastic things like a Scrabble game between 0 and 4 players with colour graphics and it INCLUDED a 16,000 word English database dictionary. Whereas the Apple computer at the time, had to leave the Scrabble game floppy disc installed as it ran it every move to check the dictionary. There were numerous chess programs some for the 16k version. I have a 48 k chess version which claims in the opening titles it beat some fancy computer somewhere. I also have the talking chess "SpecChess" which has several phrases inserted at random during play, as well as for "check" and "checkmate" etc. It was considered a marvel how they made reasonably understandable speech come from such basic sound processing. My Specturm was still like new when I shifted to Australia over 30 years ago and was STILL like new and in it's original carton when I moved back to NZ over 10 years ago. I had for a short time the "Interface 2" featured in a photo in your (earlier ?) video. But I returned it to the shop for refund as so few of the games could use an official type Spectrum joystick connected to Interface 2 (and I wasn't planning on buying full price games on plugin ROM cartridges). Instead someone good at soldering, used instructions from a local computer magazine to make up home-made "Kempston" style joystick interface for me and our friends. Kempston brand joystick interfaces were not for sale in NZ but in the UK had been released earlier than Spectrum's own joystick "Interface 2" and had become the market leader in the UK and almost every game released would load with an option for a Kempston compatible joystick. My Spectrum "should" still be ok, packed in it's carton and with associated cassette tapes for the programs and a number of books, both the originals and others I was given over the years. Plus the joystick and the home made Kempston style inerface !

"absolutely chuffed". Can tell you've just been on a trip to the UK 😀

I'd say it's definitely worth persevering with that Spectrum. Replacement membranes are, indeed, very easy to acquire as are replacement escutcheons (the metal faceplate) so, as the 'bad shape' is mainly cosmetic, please don't get disheartened at this early stage. I wouldn't use it until the RAM faults are diagnosed and fixed as further damage can occur but RAM faults, particularly upper RAM faults, are quite common and usually an easy fix. A re-cap might also be a good idea. You get a real sense of achievement when you rescue a Spectrum. ^_^

You cannot imagine the joy at receiving a spectrum for Christmas... Many thanks for the memories from the UK❤

As a owner of several versions of Spectrums, the keyboards basically remained the same and are easily disassembled. When facing the blue rubber keys, the black aluminum plate (withe the key words) is stick in place with thin dual-sided sticky tape.Using a fine flat screwdriver start working from the curved edge to gently lift it up. You will feel the stickiness. Be gentle and take your time as this plate is pure aluminum and will bend (read deform) real easy. This is the part that takes time. Once the whole left or right side is lifted off, the rest should go much easier. * Once the aluminum plate is off, you see the rubber keyboard mat which simply lifts off and can be cleaned with dish liquid soapy water and a (tooth)brush. Do not use alcohol as this can take off the ink. * Below the rubber keyboard mat is basically two transparent membranes for the keyboard. Each membrane corresponds to one connector and is either row or column. I recommend to clean these membranes with electronic contact spray cleaner and cotton balls. Clean whatever else you find. put together, and 99% the keyboard will work. * However, if the membrane has a crack close to the connector, forget about it and get new membranes. I've tried about anything to fix the tiniest cracks on those membranes, sometimes partially successful but never permanent. Good luck.

I'm not old enough to have used one as a kid, but I bought a non-working Spectrum a few years ago, and it was my first vintage computer project. After a recap and replacing the keyboard membrane, it worked for a time. Before it was all over, I replaced half the IC's. I learned alot, and enjoyed every second of it. I hope your video inspires others to take on one of these bargain wonders.

As you lifted the top cover the first time i was thinking c-a-r-e-f-u-l... watch those connectors. Can't remember how many I trimmed down as the ends wear each time you unplug them. The other place they split is at the top of the flexi where it goes inside the keyboard. The Sinclair computers had an amazing BASIC as you saw and it is worth having a working one for that alone. Not to mention the amount of games that came out over the years that used many hardware tricks to make a lowly computer give some neat game-play. Everyone put the Speccy down as being too simple but it sold massively since it was a truly affordable computer. It totally deserves to live again and goes hand in hand with the BBC since many kids had a Speccy at home and BBC at School

I grew up using these and had a BBC Micro B for years - I've gone on to spend the last 30 years working in IT. This was good fun to watch and a great blast from the past for me. Thanks.

I wrote the Teletext software for the Spectrum in 1983. Thousands of lines of assembly input using rubber keypad. Its amazing how quick your fingers learned keyboard gymnastics !

Your comment about “did anyone write programs on these” made me smile, yes, I learnt Z80 assembler on a Sinclair Spectrum. Happy days! The fun of the Spectrum was that it was a quirky machine, with clever programming it could be made to do things that I’m sure it was never intended to do. Those keyboard ribbons are part of the keyboard membrane, they become brittle with age and the connections fail. As I’m sure you know replacement membranes are available, but you do have to peel the keyboard cover off which was stuck down with double sided tape, beware it bends very easily and it’s difficult to get it back on flat. It used to be possible to get large keyboards like those on the BBC micro that you could fit the whole PCB inside, giving you a “real” keyboard and lots of room for expansion internally.

I love your explanation and tear downs. I love to watch your videos, its educational to me. I watch some others, but they don't always tear the machines down.

I had one of these (48k) back in the day, and, in my experience, the keyboard membrane wears down pretty fast... - I think I exchanged the entire keyboard membrane like four or five times over the years. I actually taught myself to write Z80 assembly language on this machine, and my crowning achievement was a real-time clock with hands that moved - all done in assembly language. Eventually, I outgrew the ZX Spectrum (and my then-girlfriend kept getting upset that I took up the TV all the time), but I learnt a lot about computers along the way, and your video sure brought back some fond memories.

It may not be financially worth repairing, but as a subject for continued content on your channel it is absolutely worth it. I'll be honest. I don't give a crap about this particular computer, but your trouble shooting steps, and repair are absolutely fascinating. I'm really enjoying following along, and would love to see this video series take us to a fully working and restored computer.

No it isn't worth your time fixing it. Yes we want to see you to do it anyway.

When I worked at Sinclair, we had a skip full of returned, dead speccy's. We never bothered fixing them and they just went in the landfill. I repaired some of them to determine their failure modes so we could improve the quality (hah!, I know, I know). The failures fell into 2 buckets. Most of the time these 64/32K chips went bad, but there were an equal number of power supply failures for the negative voltages. I'd start there....

Still got my spectrum like this in the loft in the original box. was working fine when i put it up there. Still got the tape player i used as well. Brings back memories of loading my games from tapes. Quite often they would get to the end and then say failed to load and had to start again. I remember when I bought it in the early 80s it was about £120 with some games with it.

The Speccy was the first computer I ever had as a kid. Taught myself to program BASIC and then Z80, and played 1000 games with my friends and siblings. Loved this video, even if you couldn't quite fix it! The battle-scarred look of that keyboard is how they all looked after a few months, and I got thru three of them over the years. They tended to get hot when left running (probably from that one component you pointed out), and the smell of those warm rubber keys is the smell of my childhood

This takes me back, i used to work for video vault repairing spectrums and upgrading the keyboards. There was a team of 5 people working in manchester, each repairing about 25 spectrums a day. We had diagnostic boards from sinclair that we plugged into the expansion port, it didnt get all the faults but worked well. I did hear that the guy that ran the place bought lots of stocks of chips from sinclair after they colapsed. I remeber lowering the resistor to the speaker on quite a few to make them louder. ty for the video

we started off in progrmming in 'Basic' on 'that thing' .... aahhh memories . I'm 45.

Great video been over 20 years since I last pulled apart a ZX spectrum.

I had a Timex Sinclair 1000 probably 40 years ago or so got it from circuit city back before I knew Circuit City was chain store because in our town it opened in a small trashy 700 sq ft store front in a bad part of town. This was back before Comodore 64, even before comodore Vic 20. So early in the home computer cycle. God I feel old now.

Great video, absolutely worth fixing, spent 1000's of hours on the speccy back in the day. 1000's of games, make this your #1 project! Thanks for sharing.

My friend programmed his own games for the spectrum in his bedroom as a teenager in Fraserburgh Scotland. It took months of work to make a game I believe he is one of the best computer programmers ever. When he got that ZX spectrum he could do things with it that blew my mind. He was a natural with computer’s and a brilliant mathematician and he even sold his games. So it’s possible that you have one of his games on cassette there.

brings back memories elite is a must play i spent hundreds of hours playing

I have repaired a few Spectrums, a company called Retroleum (www.retroleum.co.uk) have all the bits you need. The face plate on the keyboard is glued down, this can be removed by applying a little heat and easing off. The keyboard membrane then can be replaced, this is an easy fix. Retroleum have an upper ram module that is what you need.

I used to take a pair of scissors to the ribbons and take 5mm off each ribbon, this gives a clean contact, sometimes the contact track inside the plastic will crack like a PCB track. When in a crashed state, freeze spray a RAM chip, if the pattern on the screen changes, that chip is faulty!

I use to make and repair those, quite some time in the past and the Sinclair QL - I finished up being a microdrive engineer,,, nice to see one working

Hi Adrian, i used to repair all home computers back in the U.K in the 80's. Spectrum owners were our number 1 customers back then with what was a cheaply designed machine that broke down fairly frequently. Good news was parts were cheap and back then readily available. The keyboard membrane is replaceble and is attached to new ribbons that plug into the board. Usually when there was a memory fault one of the memory IC's would run slightly hotter than the others which was usually an indicator of which one you would need to replace (We would use the back of our finger to detect heat differences). Several other home computers used the same memory chip so you maybe able to pull a used one off another board. Also check all the circuit board tracks to the memory chips with a magnifying glass as the tracks were subject to cracking and sometimes we had to replace them with a tiny piece of wire. Hope that helps....

Would love to see your fix it I want to own some type retro computer someday and watching you fix one helps prepare me for challenges I might have also and this the main reason why I watch your video's is the repairs that you do. Thanks a lot for this vid loved it.

This brings back so much memories. I actually learned programming on this computer for the first time. I had at least 3-4 of these, because I've spent so much time with them they coudn't handle my torturing (not physically, but plugged in 15 hours a day lol). I wish I've put one aside just to have it, even damaged and not working.

I love the rubber keyboard, it was much better compared to the later plastic variety that kept sticking. The ribbon cable will easily fail because the silver pain will crack so I would add a thin stiff baking to it else it will fail. Also, ZTX650 (up to 2 Amps?) transistor is over stressed and will pop if the upgrade ram card is slightly moved so I would get a few of these transistors handy.

I know john Grant of Nine Tiles here in Cambridge UK. John is the genius behind the short cut key commands on the ZX81 and ZX Spectrum. It was done to save memory. Back in the 1980s, most kids had a Sinclair, or an Acorn. I had and Acorn. I still do. Acorn got a load of bad chips in. The test to find the good from the bad was to play Defender. Did you know that ARM (Advanced Risc Machines) was originally Acorn Risc Machine.

My god these were the computers we had in school, wow blast from the past

BBC B's were well known to suffer from dry joints on the PSU PCB even when new, although the symtom was usually a computer that wouldn't start. The company I worked for at the time maintained hundreds of "BEEBS" for Pharmacy labelling, the service desk would tell the Pharmacist to lift the machine 4"" above the counter-top and let it drop!! That generally got it working until an engineer could call with a soldering iron.

Hi Adrian, As an old time Speccy user this brings back memories for me (I'm 49) and is something I'm still quite familiar with. Something that was a dead give away which I spotted first time you booted up was that it started up too quickly. Seriously! The Spectrum did some sort of RAM test on boot up which is the black screen which clears to the (c) 1982 Sinclair Research Limited white screen. Your machine booted at the sort of speed a 16K Spectrum would, while a 48K should take noticeably longer, something like 2 or 3 seconds more black, to boot up. As such I wasn't surprised by the eventual RAM fault coming to light. This is based on personal experience of buying a 16K Spectrum mail order from Sinclair and upgrading it later (young me saved hard for the £125 the 16K machine cost. The 48K was another £50 it was the best I could afford at the time). The machine I had was an issue 2 like yours. By this point the 48K had proven popular so the issue 2 16K machine I bought was essentially a 48K machine with the 32K RAM slot empty. Interesting to note the keys change from grey the issue 1 had to blue. The cool thing was this made it easy (if rather scary at the time) for an amateur like me to purchase 3rd party chips and upgrade the machine myself - it cost £23 I believe which while worth more then than it is now, was considerably cheaper than buying official or preinstalled. The upshot is if your RAM proves faulty may also be easily replaced and fairly inexpensively. A quick word about the membrane keyboard. This is something that inevitably wore out especially with "button bashing" sport game type punishment. I eventually gave up on the idea and installed the Spectrum motherboard in a third party replacement proper keyboard case. Before that though, the other repair I was able do myself as a teenager was change the membrane. What is weird is you have to remove the metallic keyboard surround (with the upper and lower key labelling on) which is firmly stuck down with glue. This has to be done with great care so as not to bend it. It does also mean that once the new membrane is in place, you will need some sort of contact adhesive to glue the surround back on. I hope my ramblings are of some use, or interest at least. I found this page during my fact checking and stroll down memory lane, which may be of use perhaps: rk.nvg.ntnu.no/sinclair/computers/zxspectrum/spec48versions.htm Doing a quick search on Ebay UK I found this example of inexpensive upper RAM (32K upgrade) chips replacement. I imagine you'd need to buy from the US however: www.ebay.co.uk/itm/8pcs-tested-new-old-stock-4164-upper-ram-chips-for-the-Sinclair-ZX-Spectrum-/182193323977

Thank you on trying to the fix the one you have. I have one too but it’s screwed but it’s memory to me. I spectrum plus 3 too. This still works. Temperamental on the audio input but sound considering it’s now 33 years old ☺️ I’ve shared your videos to my mates ☺️

It's amazing how well Arkanoid runs on the BBC. and running on an EPROM no less! good work!

Thanks for this trip down memory lane. Used to ride my bike past competitor ACORN Computers on Cherry Hinton Road in Cambridge UK as a kid. Later my first computer was a Sinclair ZX81 on which I did my first code writing. Went on to an undistinguished programming career, but that is not the fault of the ZX81 just my own limited ability.

This ZX Spectrum deserves a complete restoration in my opinion. This is history of computing. Fixing the Speccy is not a big deal, you can easily find replacement membranes and faceplate from SellMyretro for a couple of pounds+shipping costs. Also your colours issue may have two culprits which can either be a simple tweak of the trimmable resistors or either a replacement of the colour encoder LM1889. For the faulty RAM on the 48K bank those are easy to find and replace at a very cheap price. It's well worth it!

You have to fix it!!!!! I’m American and I bought a ZedEx Spectrum off eBay years ago for the hell of it. After a month it got here and didn’t work :( while I was resoldering the ram chips the keyboard connectors disintegrated and I had to wait another month for a replacement from England. After getting a compatible 720p upscaler and a shielded video cable I was playing Exolon like a proper English lad....

Funny story....back in the days of the spectrum I worked for British Telecom ( Built a Nascom computer back then). The telephone exchange ran mainly on relays with some transistor tech. They were way behind on computing. We used to have tours of the exchange and there was a rack with what was called a translator which was full of transistors etc. The guide used to take the cover off and show the visitors how complicated it was ( Not). For a joke , we got a spectrum and stuck it in the front of all the relays/transistors so it looked like it was part of the gear. The guide proudly announced that this rack was the most complicated part of the exchange and the exchange would not work without it. He removed the cover ( tadaaaaaa) and all the youngsters starting laughing. He turn to look at the rack and kept a dead pan face and said and " we can also play games on it". We all had a good laugh afterwards. They probably went home and told their friends the exchange runs on a spectrum. In reality the spectrum was probably far superior to the installed technology.

It was interesting seeing that video.. Nice work by the way. I had several years back.. The keyboards were a problem.. I replaced mine out for one of the Fuller keyboard replacements. The Fuller case/keyboard turned the 48k Spectrum into a decent computer... great video

Love you use of the word "chuffed", very British. The BBC Micro B was my first computer, and I modified the hell out of it. I had dual 360K floppies, the digital voice chips, external ROM ZIF socket, second processor on the tube interface, acoustic dial up modem, home made interface board on the 1MHz bus and spent far too much time cracking game protection. good days.

When I was a kid, a ZX Spectrum popped up in one of my local thrift store in Montana (of all places). My dad didn't know anything about it, but recognized my willingness to learn and bought it for me. I was even entering into a newly formed Science and Technology elementary school where my teacher had a wide array of her personal IBM machines available to the students who took the ZX Spectrum to try and fix it for me. Unfortunately, she and her friends found it to be entirely ruined. I'm pretty sure that if that thing had worked, I would've gotten into programming at an even younger age than I did.

Started with the ZX81, but it was the Spectrum that I truly fell in Love with.

Ah, the BBC-B. After getting into home computing with a ZX81, we decided to get more serious with a BBC-B. We sat down and discussed this for a few days, as £399 was a lot of money in the early 80's. What a machine! So much faster than the Sinclair and with plenty of connectivity for external projects. We still have it, and every now & then it gets plugged in just to check it still works. It does!

That’s what got me into programming bbc basic 30 years ago. Great experience we where blessed and had these in are class room. I was actually lucky had one at home. However all games didn’t come on EPROMs it was only like word processers that did most games actually loaded form 5 1/4” disc.

Maybe a year too late, but i used to fix these all day long. Keyboard cables - clean the ends with a rubber eraser. ZTX500 - replace with ZTX600. Scope the data pins on the ram and the bad chip generally looks different on the 'scope. The ULA always fails due to heat. Great move giving it some heatsink.

Great video as always

Way back when this was state of the art I repaired these for a living. They are primitive but yet they were surprisingly reliable as long as the customers didn't do anything too stupid. The really weak spot was the edge connector which gives you access to all the signals on the CPU bus.There is nothing to protect the circuitry so anyone trying to connect or disconnect a device wile the power was on ran the risk of killing the computer. I remember one lady who came in with her sons machine several times only days apart. It was just a few weeks old and still under warranty so the first time we repaired it and didn't think more about it. When she came back a few days later and it was dead again we asked her if anything had happened that she thought might have anything to do with it, but no she couldn't think of anything. Well it was strange that it had died again, and that the fault was exactly the same as last time. So we mentioned that usually something like this could happen if you plugged in or unplugged a device like the printer or a joystick interface while the machine was powered up. It could also happen if the connector on any such device was damaged. But no, she was certain her son didn't cause this, that was impossible. The third time she came back, it was just a few days later, it turned out to be the exact same problem again, and this time she was quite agitated and complained about the quality of the machine. We took a good look at the edge connector and it looked like there were faint scratches there. So again we asked if she was certain her son hadn't tried to connect a device with the machine powered on. Now she got upset and explained that she was certain because he didn't have anything like that. He had no printer, no joystick interface or anything else, just the computer, so it was impossible that it was his fault. So we told her that we had to ask as it was very unusual that they died like this so many times. And then we took the machine to the shop, repaired it and painted the edge connector with nail polish. The next day she was back, and now she was livid. Not only were we incompetent as we couldn't repair her sons computer without it breaking regularly, but now her son told her the joystick didn't work when he got it back! I still remember her face as I calmly said that it was strange, just yesterday she had told us her son didn't have a joystick interface, and now she complained that it didn't work. Now how could that be? After some sputtering she said he got it as a present yesterday. So we told her that was a very good gift to her kid, just remember to tell him to never try to attach or detach it while the computer was powered on. Now if she could just wait a few minutes we would make sure it would work. So we took the machine back into the shop and rubbed off the nail polish from the connector, and that was the last time we saw that machine... As for the memory problem I remember most of those was easy to find using a multimeter. Now I can't remember what pin we was probing but at least 90% of the time the bad chip measured low. If that didn't work we had a diagnostic board that ran a memory test and pinpointed any chip that failed. It was an interesting time with new computers coming out all the time, and we're not talking just another IBM PC copy. We also repaired the Atari ST and the Commodore Amiga. There was very different in construction, though both used the same processor the circuitry was very different. The Atari was built down to a price point with just the bare minimum of components. Anything that could be excluded was left out. The Amiga on the other hand could be used as a teaching aid showing how you are supposed to design a circuit. And yet we had a much higher failure rate for the Amiga than the ST. Another fun device was the Sinclair Microdrive. They used a miniscule tape cartridge containing a endless loop of tape that to increase the capacity was twisted into a möbius band. That way the tape had to pass the read head twice to access both sides of the tape. It sounds ridiculous but actually worked surprisingly well. Well compared to a floppy it was both slow and prone to failure, but there were ways to improve on the reliability. One quirk was that the tape in a new cartridge tended to stretch a bit before stabilizing. If the tape was just formatted once and then used to store data it tended to fail after a while as the tape stretched and the data became unreadable. A new cartridge typically formatted to about 85KB (yep not even 100KB, different times). I hacked together a bit of code that just reformatted a tape over and over again, and after a while the tape would format to somewhere between 95 and 105 KB, after which it didn't seem to stretch much any more. After that it seemed the tape was much more reliable. The interface used to connect the Microdrive to the Spectrum was another interesting device. It could be used to connect up to eight Microdrives to a Spectrum, and it allowed up to 64 machines to be connected in a network. Any machine on the network could access any microdrive on any other machine on the network. There were no security whatsoever though so you could really mess things up if you wanted to. I don't remember any commercial games that allowed for network gaming, but I hacked together some software for real time messaging and remember working on a actual game, but I never got past the roughing stage. There wasn't exactly many who had a network of these to play on anyway, so it would just have been for me and my friends. Another big problem was that the network wasn't what I'd call stable- Messages was lost and connections dropped. If two machines tried to send at the same time bad things could happen. But it was a fun toy at a time when local area networking wasn't really standardised or an everyday thing.

I remember visiting the Sinclair offices, outside Cambridge just before they auctioned off everything and shut down. There was a room full, floor to ceiling of customer returned units. We just missed out in a bid for their Vax computer. :-) Happy days!

It was so nice to watch this video...something I needed. I'm at wits end with my attempted repair of the issue 2 board. Everyone screamed at me to replace the caps and of course I finally did and no change. I know you've said those early 80's caps aren't usually the issue but someone pointed out that if they are off a bit then the lower RAM doesn't get initialized at the right time and even though the voltages are correct they weren't during critical boot-up...dunno. My entire issue 2 is now socketed (the upper ram came that way). I've tested all the ram and replaced the cpu (which was bad) and now I just get stuck at the check RAM screen (i.e. the ROM checks how much it has). The only two chips I haven't tested is the ULA and the ROM. I'm planning on getting an EPROM programmer and burning my own (requires a small mod to the board which I hate to do because I feel like I'm adding something to a non-working board). Unfortunately I don't own a scope. In any case, I felt like a failure after two tries and it's nice to see someone more experienced also having struggled.

“Now, how does this keyboard unplug?” (Sinclair owners everywhere) “Oh no”.

Hi glad I came across your channel 👍 I had a spetrum128k tape deck on side many moons ago 😎

I have read the other comments about the key board and I do agree. In my experience with the membrane types is "It is a bad idea to unplug them at all" So it might have been better to test before opening the case. Thank you for the great videos.

Before the time of paint programs i used this for computer artwork using Basic programming, learnt a whole lot of programming on the zx spectrum. I think i was 11 or 12 years old then.

the keyboard membrane and the ribbon cables are all one part and cost around £9 ($12) in the UK but unfortunately it looks like it will cost you at least that again in shipping costs. Also reproduction faceplates are available if you want the machine to look like new again. If you have plans to come to the UK again maybe leave the Spectrum until then and pick up the parts you need over here

The Spectrum's rubber keyboard was awesome when you had nothing to compare it to. That was my first computer. With the help of a rosy mist of nostalgia they were the best computers ever.

That's a real shame that it failed towards the end dude, I was really excited to see someone who's never really used one of these before be excited by it =) I reckon it's fixable, but as people say you might be better getting one of the later 128k models like a +2a or similar. I genuinely hope you get something that works for you though.

Back in the day I would just cut off the end of the flex connector and try again. Essential to minimize the movement on it.

Great videos. Thank you.

BBC and -5V : Not a BBC-micro guy, but out of curiosity I recently saw a long interview with Steve Furber (designer of the BBC). He said - based on feedback from users over 30 years etc. - that *the* thing that goes wrong with the BBC is the power supply and it is dried up capacitors (one or more, I can't remember). Whenever it acts weird or wont work, replace cap(s) and you're fine. Just relaying information, can't go into details, hope it helps...

It's challenging you, and that challenge must be met!!!

The keyboard metal plate is stuck on the top plastic case by a double sided sellotape on either side and this can be easily praised out to reveal the membrane, wash and clean the rubber (only) with mild soap, and check the membrane connector for cracks, conductive silver can repair that but you will need to stiffen it slightly with a backing so when it is inserted back it will not crack as the lid is shut. All good fun.

Great video !

Adrian, Spectrums came with both 16K & 48K from the factory (prices circa 1983 were £99 & £125 respectively). Sinclair offered a 48K upgrade for 16K owners. Yours's was definitely 48K from the factory. As somebody has already said, the keyboard membrane has the connecting cables integrated. A new keyboard membrane isn't too expensive but you've got to factor in shipping costs from the UK. Something I did back in the day was to trim the ends of the ribbon cables to ensure a better connection. Sometimes it worked. It isn't about the money on this rebuild. It makes for great content.

Hi there, Adrian! Nice video! I loved to see the original ZX insides, since it had a Brazilian copy in the 1980's called TK-85 which was made and sold by Microdigital. Just a couple of advices about the video (which you probably already know of, but anyway...): 1- To avoid horizontal banding in your television set screen, record the video at a shutter speed equal or multiple of your local AC frequency (in a regular DSLR or mirrorless camera that would be 1/50, 1/100, 1/200, 1/250 etc); 2- To avois "focus hunting", sinco all your takes are static (camera on tripod), use manual focus to avoid the focussing system detecting sudden higher contrast areas and trying to change the focus. Cheers!

This was the third computer I owned, previously had the ZX80 and the ZX81. If your family didn't have too much money, there really wasn't any other option but Sinclair. My Spectrum lasted me about 3 years in total and was patched up many times. I got the ram expansion that 'plugged' into the back. I put plugged in inverted commas, as it didn't so much plug as kinda hang in place. You'd be coding away and accidentally brush against the ram expansion and the system would reboot - goodbye code. I eventually taped the damn thing in place. The keyboard went - pretty much exactly like in this video - I fixed it, believe it or not, with bits of tin foil. I had no other resources to use. I must've patched that keyboard 20 or 30 times with bits of foil. As for programming it - oh yeah, I coded, big time. At first, it was 'Hello world' stuff. Then I started getting a magazine called 'Your Computer' which came out monthly and had programs you could type in. I spent laborious hours typing away - a lot of the code was hex, basically, machine code. My typing skills were honed and never left me - I can touch type to this day due to the amount of hours I spent hunched over that spectrum. I then started to learn to code and got pretty damn good at it. I coded the game 'mastermind', a whole bunch of simple platformers and got half way through coding a pacman game. I never did manage to stop the ghosts from randomly going through the maze walls. Because basic was so slow on the spectrum, I bought a compiler program with my pocket money (saved for months!), which would take the BASIC and compile it to assembly. It made programs run about 1000x faster. It was so fast, I had to introduce empty loops in my basic code to slow things down. The keyboard was absolutely crap, but crazily enough, I did learn all of those bizarre key combinations to speed up typing - and it really did work. Toward the end of my time with the spectrum, when the keyboard finally gave up the ghost, I got an upgrade to the spectrum with the solid keyboard. By that time, however, I had discovered guitars, girls and booze - it would be many years until I got acquainted with computers and code again. Those were the days!

We had one when I was a kid. It was 48k from the get-go. I never heard of a 16k zx spectrum but the zx spectrum was always referenced with the '48k' as part of the title in everything I read even before the 128k came out with the plastic keycaps. I /did/ hear of a predecessor to the zx spectrum that sinclair made with 16k RAM. Bear in mind I was a kid and might not have read or cared about any references to a 16k model just because that's what kids are like.

16k models came with empty dip sockets for the extra ram, they were plug n play. I have fond memories of the old rubber beermat Spectrum, and the BBC model B too.

I wrote my first program on one of these. It was a critical path analysis program for a project I was working on as an engineer. I ran it a couple of times thinking it did not work. Eventually I ran it overnight and the following morning at 4 am it spat out the results on my dot matrix printer. I cannot tell you how chuffed I was. One had to save the programmes on a cassette tape. Things are much easier now.

Awesome memories for me,I started my 80's teen computer love affair with a zx81 then a 48k/128k/+2 and +3 spectrum before moving onto a vic 20.I sold all my old toys to help pay for them.The 48k was constantly breaking down and took ages to be repaired,usually 6 weeks to 2 months,it used to drive me nuts.I remember fondly spending days and days typing in magazine game programs on that awful rubber keyboard only for them to fail to run,those were the days,kids today havn't got a clue just how lucky they are,lol

The Spectrum is probably being under powered (the extra memory requires more juice) crank it back to 1.2 amps, or use a PSU like an Atari Jaguar which works find on all the original Sinclair Spectrum up to the 128K. In my opinion I loved the Issue 1, even with it's quirks. It was this version which gave the Spectrum it's rear hump as the memory expansion was on a daughter board. Pretty cool for back in the day. If you can find a broken Spectrum +, this will fit directly inside it so you can have a roomier case and better keyboard.

I used to have problems with the membrane keyboard, too. But not anymore! I drilled holes under the rubber keys. If everything is removed, the top plastic part under the aluminium cover and the rubber keys will show where to drill. And I have bought a lot of those square tactile switches(buttons with four or two legs) that are used to be in the front panel of DVD's, VCR's and things like that. And I wired them in on the Spectrum motherboard and they work fine ever since.

Excellent video as always, Adrian. If you think typing on the Speccy is hard work... you should've tried it on the ZX81! OMG! All the best from the UK! Paul

Thanks for your wonderful on restoring the Spectrum computer. I really enjoy your restoration videos, mainly because I lack the skill, knowledge and confidence to do what you do on the videos. If you are opening to completing the restoration, I would love to see how you do it.

The lines through the colours is due to dot crawl. You may have noticed there are two crystals in there.. one generates the system clock and one generates the PAL colourburst frequency. Because they are not in sync with each other, you get dot crawl. They addressed this issue on the later 128K machines. You may find adjusting TC2 helps

"UK Basement" ;) Not in the UK Adrian. We don't do basements. We do indeed do attics, or lofts, or as most commonly known here in the UK, the roof space. Gosh you brought some memories back. I've two of those speccys in my lost and a BBC master with CUB monitor somewhere up there too. I should hunt them out sometime... Haven't been used in 30 years.

Back in the mid 1980's our local Super Value Store had a promotion, buy a meat bundle and get a free computer, it was the Timex Sinclare. I never got one from the store, but a buddy of mine did, and a few years later I fixed one of his pistols for him, and he gave me the Sinclare for my trouble. I never used it much and took it to a gun show where I traded it off for an Italian Cracano rifle which were valued at about ten bucks back then if you could find anyone who wanted one to use as a fence post or something. I was into computers back then, had a C=128 and later upgraded to a 386SX, from then on I had one or more computers. Today there must be twenty computers laying around my house, some old enough to run Win 3.1 (Compaq Laptops) up to my current laptop that came with Win 10 ( like 3.1 better but then no INTERNET, so what can you do?)

Get yourself a Kempston interface. It fits to the expansion port and allows you to use any 80s or 90s 9-pin joystick.

I bought a 16k spectrum in 1982. I couldn't afford the 48k at the time. Soon after I realised that most of the games wouldn't run on the 16k model so I bought an aftermarket upgrade to 48k. If I remember correctly the instructions were to prise the old chips off the board with the handle of a spoon and push the new ones in!

This was my generation......80s....kids growing up into this world and improving it to what we have now......releasing the technology to the public to play with...is why computers have improved

There are so many upgrades available for things like the keyboard and fixes for ulas and ram issues. Big enthusiast computer even now.

I had one of the Timex/Sinclair computers which was sold here in the United States and it worked fine for a long time until the ribbon running to the keyboard finally broke and needed repair, but after putting it in the shop once I didn't want to do it again since the local Timex plant had closed by that time. It was my first computer and I got it cheaply since the drug store I got it from wanted to get it out of the store.

Just FYI, the standard "white" background colour on the Spectrum's display is not very high intensity by default--there was a BRIGHT attribute that could be applied to each colour square which would make all the colours much brighter, including the white, but it was rarely used in practice.

I replaced my Model B PSU with a modern unit via a member of a Facebook group here in the UK. Going to try recapping one of the others I own. The Spectrum was a classic of it's day, and I own all of the models produced over here, and then some! Responsible for a whole generation of programmers.

Takes me back to the heyday of the Radio Shack Color Computer. The earliest versions used RAM chips that needed 12 volts. The upgrade from 4K you had to disconnect the 12 volt line and use it as an address bus line. A7 wasn't even connected so to get 64K you had to add two wires. The voltage doubler is like that in the Tandy/Radio Shack MC10, it's only needed for the modulator and the computer runs fine on 9V DC just no RF. The later 4K chips didn't use 12 V but A7 still wasn't connected. Sounds like there's plenty of scope to carry on with the Spectrum. Good luck.

I'm in the U.S. and remember when Sinclair launched the Spectrum, and it was available in either a 16K or a 48K configuration. The 48K version was far more popular, so much of the software that was developed required 48K. Having learned a bit of Sinclair Basic on my brother's ZX81, I wanted a spectrum. Sadly, it was never released in the U.S. Instead, Timex partnered with Sinclair and released the TS2068, which I bought, but it didn't run most Spectrum programs. About a year later, Timex abandoned the personal computer market, so the TS2068 never received much support. Although I still have my TS2068, I ended up buying several Spectrums (Spectra?) on Ebay to play with a few years ago. Most of them work, although the keyboard membranes needed to be replaced on a couple of them. I had to perform a composite monitor modification to get them to display on any TV or monitor I had available. After the mod, I connected one of them to my flat screen TV and it displayed quite nicely. When I replaced my keyboard membranes, I also replaced one or two of the faceplates. I found the replacement parts on a website called "sell my retro," which can easily be found with a web search. Now you can find faceplates, and even replacement cases and keyboard "mats," in a variety of colors, to build a spectrum in the color scheme of your choosing. There are even modern Spectrum compatible motherboards available so you can build a modern Spectrum without any original Spectrum parts!

Sinclair Spectrum was one of the most cloned computers in Europe. Spain had his clone and here in Portugal Timex made an "official" clone of it, the TC2048, an improved version os the TS2048. The collaboration between Timex Portugal and Sinclair was so close that some genuine Sinclair Spectrum were produced here in Portugal along the Timex clones! Today you can visit at the town of Cantanhede, in the center of Portugal the greatest museum focused on Sinclair Spectrum and several clones, among other Timex and Sinclair products like calculators, diagnostic devices for electronics and even... the infamous C5! =)

If you've got problems with the RAM chips there are a couple of replacement options. I suspect the original 4532 chips which make up the upper 32K are hard to find, but an alternative is to put 4164s in their place. These are available relatively cheaply on Aliexpress. There may be a mod required in order to lock the chips into using either the upper or lower part of the 64K. It's also possible to replace the DRAM with SRAM with a latch to hold half the address between the RAS/CAS cycle. This can be a do it yourself job (as the details are available online) or there are people selling boards that can be plugged in once all the existing chips have been removed and sockets installed. The 32K RAM chips and associated circuitry came pre-installed in that model. The 16K models were only produced for a short time after which only the 48K ones were produced. The board design was significantly different though as the extra 32K was designed to be added using a daughterboard that plugged in between two DIP sockets. I did come across an after market version of this board which added 64K chips to the setup and allowed them to be paged giving the machine 80K total, but these are somewhat of a rarity. As for the keyboard, replacement membranes are available and you can also get the cover plates as well, ebay being one place to look. There are modern replacements for the case and keyboard available some of which come in alternative colour schemes (retroradionics.co.uk/shop.html#!/ZX-SPECTRUM-replica-case/p/75106216/category=0 being an example). It is also possible to find keyboard upgrades from the period, although these are harder to find as the vast majority of machines were left in their original cases. You're also not likely to find one that does not already have a Spectrum board installed in it. That said, it is still possible to find the Spectrum+ upgrade cases available on ebay from time to time.

Oh the memories. Teaching myself BASIC. Teaching myself Z80 assembly language. Having to explain to my Mum how I'd broken yet another joystick thanks to "Daley Thompson's Decathlon". Having to replace the keyboard membrane twice. Jet Set Willy. Manic Miner. Elite and the dumb lenslok (I still have both that and the game in it's case). "The Way of the Exploding Fist". Digging it out of the loft to pit the chess ROM cartridge against the SNES (the spectrum lost big-time). Etc etc etc.

Had a ZX when I was a kid. Remember those rubber keys.. Crazy azimut tweaking of the casette driver.. All wasent better in the old days..

In my experience when you have a simple voltage source like that -5 that comes and goes, 9 times out of 10 it is a cold solder joint or cracked trace on the board rather than a transformer problem. The problem isn't always visible, even with a magnifying glass. I'd start by resoldering those half-dozen component pads in that circuit.

Lo and behold... Definitely a bloke that's been to England as he gets 'chuffed' when he gets a positive result

When you've worked with spectrums for a while, you get a feeling for how long the computers ramtest (the short period before (C) 1982 Sinclair... appears) should take. That looked more like a 16K ram test than a 48K one. You can check the last memory location tested as good by the spectrum with "PRINT PEEK 23732+256*PEEK 23733". It will be 32767 for a functioning 16K model, and 65535 for a functioning 48k model. All memory locations are filled with the decial value 2, then every locations value is decremented and a check is made that the value is non-zero. Every value is then decremented again and a new check that the value is zero is now made. If either of these two checks fail, then the memory check is aborted and the address of the last good check is noted in 23732/23733 (RAMTOP)

This was/is my very first PC which I still own in the original box. I spent hours and hours prgramming games on this computer and hours re-entering the code after a power outage etc. Good times.

the spectrum was my second compute. i remember the fun of two player games on that keyboard. it was a big improvement on the ZX81 a whole 1k to work with lol

Those BBC machines look very similar to 6809E Colour Dragons, I used to code assembler on those. The ZX had also been available in electronic magazines in 1980 for around £148.

Damn. Someone that knows what i was looking at thirty years ago when I took apart my Spectrum mine di not have the Heath-Robinson fixes on the chips so I guess it was issue one. I have to say I feel your pain about the paint. Most of mine was gone in the left upper section where my fingers rubbed against it playing Chucky Egg 2. Hope you get it working.