Sinclair ZX Spectrum +3 and 3" Disk Drive Repair
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- čas přidán 11. 03. 2020
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We take a look at the last of the ZX Spectrum models: The +3 with integrated floppy disk drive. We run into several issues, and we can't exactly repair them all, but in the end we leave it in a working state.
First the power supply wasn't working. We took it apart and looked for problems, but we had to simply replace it with a working power supply.
Then the Spectrum wouldn't start up correctly and would give a garbled initial screen. That we did track down to overloading the 5V line and a bad capacitor.
Finally, we did some servicing of the 3" floppy disk drive, but it still didn't work. We tracked it down to a likely misaligned step motor, but had to end up replacing the drive with a working one.
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It's one of those little pleasures just to watch Noel apply the scientific method in every video 🤓💾🔬🧫.
Oh nice trick with the shrink tube! Thanks !
I thought that chip on the disk drive was shorted. It had a big blob of solder on it, but the other one had it too. Very odd.
If you do not get anything from any of the secondaries of that PSU, maybe the primary is open. Check on the mains plug (when unplugged!) for resistance, you should get something. If it's open then your only hope is that one of those copper wires going to the 240V pins is broken so you can patch it up. Great video as usual!! :)
I did check that the input to the transformer was getting 240V, so the transformer itself (or some of the fuses) must be bad.
Hi Noel, again a really nice video. Even just including the simple shrink tube protection (while measuring) was a nice touch.
Thanks! Glad you liked the trick :-) Comes in really handy for C64 power supplies as well.
Thumbs up Noel....excellent job
Fantastic video! Really enjoyed
Just great... This was essentially an amazing mechanic work. Bless SD's and SSD's...
My favorite spectrum. My brother brought me one when they were new. Can't wait to get another one again. Great video
Thanks! Yeah, it's a great Spectrum. Too bad it wasn't supported more with disk software. If only it had come out a few years earlier...
Many times there is a thermal fuse on the input of the transformer. sometimes the legs of the thermo fuse are soldered to the terminal or you have to remove the plastic cover to see if you see it.
if the computer draws extra power, the power supply can be overloaded over time!
Good video Noel as always, and great to see an Amstrad CPC to the rescue :-)
Thanks Niall! Yes, little guest appearance here. Maybe next time it'll be a 664 coming to the rescue :-)
As a boy I drooled over this machine LOL.
This is just so therapeutic
The transformer also has a fuse(or at least it should have) on the input side!! Make sure you check that out before dumping it !!
Yes, it must be that thermofuse blown up.
Hi Noel, wonderful vids BTW, this might come late but normaly in the transformer primary side there is a thermal fuse and taking off the first layers of tape from it will reveal it, worth giving it a try.
Noel: I don't want to remove the pcb for cleaning because removing it is a pain in the *.
Floppy drive: I heard that! You will remove TWO as a punishment :)
Wow that brought back so many memories trying to replace the CPC's drive belt and cleaning it to make it work!
BTW at 23:16 it's also labelled correctly "Jh R" (red), but it's on the bottom left, next to the jumper pin.
Yes, the drives are identical. And yes, the drive belts almost always need replacing. It's kind of amazing they used something so low tech even when the CPC was released! Cheap Mr. Sugar! 😃
Love the heat shrink tip. Nice video Noel!
Thanks! Much appreciated.
Yes very helpful
@5:05 should check the resistance on the primary coil at that point, saves a lot of time. The primaries are often very fine gauge wire and I have seen many where it is clearly under-spec'ed for the load and has burned through cause open circuit which gives the same diags you have here.
Must be the primary because none of the secondaries is reading anything.
Awesome dood.
Nice trick for the tubes around the pins to test.
I'll use this one :)
Thanks! Yes, I use that quite a bit for power supplies with pins like that. Quite handy!
@@NoelsRetroLab Typically the kind of thing where the reaction is :
"Why did I never had this idea before ? Me stupid !" :P
BTW, I discovereved your channel quite recently, and since I'm also in electronic, there's a lot of useful information.
Not only for old computers (I don't have any in fact, unless a P2 333 is vintage), but for the methodology to understand failures and solve them.
I also follow the usual 8BitGuy, RetroRecipies and others, but they are not as much in electronic IMHO.
It is a shock for me, because there are no videos in Noel´s Retro Lab about the Commodore 16.
That's true! It's a system I have never done anything with 😱 I'll have to set that straight one of these days.
@ 2:22 that is an excellent life hack thanks! :)
at last a real video no lies so many tell lies when doing repairs big time
I try to show everyrthing: the fun repairs, the awesome insights, and the dead end failures. I just cut the boring parts where nothing happens 😃
RIP Sir Clive Sinclair
Very sad to hear the news today 😔
The tip on the shrink wrap made it worth it alone and am only a few minutes in :-D
Haha, I had to re-watch it to figure out what you meant. I had forgotten I mentioned that trick here while testing the power supply 😀
A word of friendly advice Noel.... before you even plug a power supply in to a unit, ALWAYS test it from proper voltages first. Nothing toasts chips faster than over-voltages. In electronics class some 30 years ago, the teacher would read you the riot act if you ever turned on any unit without first testing the power, whether or not is was new or used.
7
@@TheCanuck1976 7?
Hi. In your place I would use the plastic case of that original PSU and put a modern one inside. That would be a nice video too ;). I've done that several times with the C=64 and the Amiga ones.
Yes, that's probably the way to go. I might make a video when I get around to it. Cheers!
Did you put the write protect pin back in? Trying to work out where it goes. Thanks
Nice as usually Noel's videos :). Noel, did you checked the diode on circuit with the cables red/brown on the top of the driver?
Thanks! I didn't check it, no. Do you think it can be related to the read error? Is it some kind of rotation sensor or disk sensor?
@@NoelsRetroLab I'm not sure, but it is the only "electronic" part of the device that you didn't check it, it is rotating, moving the head, you changed the disk belt, put some oil on the gears... maybe it is not, but it was what left.
@@NoelsRetroLab This part is on charge of center the optical part to find the index.
It makes some sense when all is working but nothing is found trying to read the disk
Got to love the ZX Spectrum. Mine was the +2B, which is essentially the +3 with a cassette drive instead of a floppy disk drive. Annoyingly, Amstrad promised that their external drive 3" drive for the CPC range would be compatible with the +2A and +2B, but it never was. (I'm not even sure if the external 3" floppy drive was ever even released for the Amstrad range, as I wasn't a CPC user. But if it exists, it would sure be an interesting project to make it work on the +2A and +2B range.
There was definitely an external floppy disk drive for Amstrad CPC. It was called DDI-1 (www.cpcwiki.eu/index.php/Amstrad_External_Disk_Drive). I didn't know about that promise from Amstrad, and I'm actually surprised it wouldn't work because the drive is the same. But now that I think about it, it's the drive plus the controller, and I suppose that might be different. Or maybe it's just a matter of having a different connector.
One thing you can do with certain boards of a ZX Spectrum +2 is add the chips that the +3 had, and hook up a disk drive. If I come across one of those boards I might do a video on that.
The lack of an external drive for the +2B made it a CP/M machine that couldn't, in fact, run CP/M.
Great vid. I've got the PCB of a +3 that needs looking at (got it for £5 off ebay). Had it for a couple of years now, still have'nt pluged it in. LOL
Nice! That's a great deal on the PCB. I have another +3 with a busted ASIC and I'm looking for a replacement one (or a +2A with the long board). If you decide you don't need it, let me know and I'll buy it from you :-)
Hi. Thanks for the video.
Can you please tell what are those cartridges you use for testing? Thanks again. Cheers
You're welcome! That cartridge is a ZX Dandanator Mini. It's a great add-on for loading games in general, but it's fantastic for testing. Highly recommended.
I can't remember how many times I had problems with that fuse.
often on the primary winding their be a fusible link near where power connects, you may need to peel back the insulation to find it, or the thin primary winding breaks where it connects.
It's been a while, but I believe I checked that and it was fine, but I could be wrong. I think it's supposed to be a thermal fuse.
I've just replaced the belt but the drive isn't reading disks, typing CAT into basic results in "drive not ready" any ideas? Thanks!
My last ZX Spectrum was ZS Scorpion 256. First one was some unnamed ZX 48KB clone with tape loading. But ZS Scorpion was a really good one. Mine had nice small desktop case (horizontal) sporting 2 5.25" inch floppies, keyboard (ZX+ style) was external - PC style. Clone was .. i would say 99.9999% compatible. It had correct implementation of FF port, two joysticks and printer port.
As it's name implies - it had 256KB of RAM and same amount of ROM which containted a lot of utilities, plus you could replace it with "professional" 512KB ROM with even more good stuff like debugger and other tools which allowed you to stop any game at any time, enter POKEs and continue.
Disc system was the dominant one used in the Eastern Europe and USSR - Beta Disc Interface with TR-DOS 5.03 or some later versions which had customizations.
Wow, that must have been really interesting. I need to learn more about the ZX Spectrum evolution beyond the +3. I have a Pentagon kit to assemble, but the one you describe sounds really advanced! I should look for one on Ebay, although I'm sure they're not cheap.
@@NoelsRetroLab To my knowledge ATM-Turbo is still being produced in small quantities. It is most powerful Speccy-clone produced i would say, NEXT excluding. It had 512 or even 1024KB of RAM, Z80 Turbo modes with 7 and 14MHz, IDE controller, ability to connect PS/2 mouse and LPT printer port. If my memory serves me right, it also had enhanced display modes - IBM EGA compatible plus CP/M support.
@@NoelsRetroLab I am from Latvia. My first Speccy experience was in 1990/1991 when our country was still in USSR. I was 15 and studying electronics in Technical college. I had a friend who had a friend whose father was some Communist Party bigwig who often had business trips to the West. And he brough his son a Spectrum. It was black and sleek and had cool keyboard - now i know it was ZX Spectrum+. We often visited him and played games. I still remember first three games we played:
Flying Shark (that yellow-ish vertical scroller with WW1 era biplane shooting things)
Alien 8 (Knight Lore-like game, well known i think)
Treasure Island Dizzy which had huge impact on me and Dizzy is still among my favorite game characters.
In the East Speccy continued to thrive for some more years after it went on decline in West. These days East also has active retro community which i know actively seeks and establishes contacts with similar communities in the West.
Just take a good care of that beauty! .... By the way, I've got the extremely rare romanian clone HC2000 in perfectly working condition.
I was always told not to test Fuses whilst they are in place and to always test them out of their housing for a more accurate test.
thank you for posting. i had never heard of this computer before. my ignorance knows no boundaries. i might have opted for a cool-running modern power supply, camouflaged in the old-school housing. is the floppy disk actually 3", or is it the same as the familiar 3.5" fd ? take care & stay safe.
It wasn't the most popular ZX Spectrum model, so that's not too surprising (especially if you're not based in the UK). You're right about the modern power supply. The only problem is that it needs to output 3 different voltages, but I'll look into fitting one in that case in a future video. As for the drive, oh no, it was a real 3" disk drive. Amstrad loved using those in their CPC and PCW ranges!
Did you check the primary winding of the transformer for continuity? They sometimes have a thermal fuse in series under the tape that may have blown.
I think I did and it was fine, but I can't remember anymore.
Hi Noel.. Question for you. Will a composite mod work on this as it does on the 48K models? I just picked one up and I'd like to test it without hauling the "big TV" out!
It would but... you probably don't want to do that. The monitor connector on the back has both RGB and composite out. So you could just grab the composite signal from there if RGB is a no-no.
@@NoelsRetroLab I was reading into from bytedelight and apparently, on the +3, the pin you would expect to find composite video on is actually 12V. I'll be careful and probe around first
dead transformer sounds weird. because it its in a good shape. is there thermal fuse under yellow sticker?
👍 ❤
Check termal fuse in primar coil. ;)
That transformer probably has a thermal fuse which has failed. It's usually buried with the windings, but near the surface. I've repaired tonnes of transformers with this fault. It's messy but it is repairable.
You can tell that 5v rail cap was bad by the contamination around the ASIC. I'd go ahead and change the rest of them including the power supply. It may be a reason the transformer failed if it got too hot
Hi Noel, i have the same drive and want to scope for the allignment. Problem is, i don't find the testpoint to place on the scope. Also, is there a vid to show how to adjust/check track 0 optical switch.
They're usually labeled as TP1 or TP2. They're just solder points, no actual leads or connectors. I haven't done the one about the track 0, but it involves tiny movements and repeated "CAT" commands. Haha, I'm afraid not more scientific than that 😃
@@NoelsRetroLab Thx for the reply, but on my EME-156 model ME56PB31 there are no marked spots with TP1 or so. But, reading the forums, for that type you need to test on TP5. That should be near R18 marked with "W". So, i'll will mount the drive back in and see if the scope see any variations when adjusting the stepper drive.
For that specifique drive, the Testpoints are grouped as a 5-pin connector on the top right side of the board (how did i didn't notice that)
They should have gone with a Direct Drive Disc Motor like they had on the 1.44MB Floppy Drives.
Hey would you ever consider doing a video on how to add a compact flash to this model or another of your 128k units? I am looking at importing one of these units to the states and read it is pretty advisable to do so here because games are so rare for it. I'll have to do the composite mod as well since the whole 50hz tv thing. Speccy games are just so unbelievably fun.
It's on my list somewhere, but you can probably find quite a bit of information out there already. I'm actually very interested in how you deal with a Spectrum in the US. Can you change the Spectrum to output NTSC video? Or do you just use RGB? (which I understand it's not as easy to use with US TVs as it is in Europe with SCART).
@@NoelsRetroLab I am going to go from RGB to HDMI. I am not sure if It will work but they make SCART to HDMI converters. That would be easiest. Otherwise I saw your video on where to grab the RGB signal internally. When I first started watching you I thought you were British. When you speak in English your accent is almost undetectable. I didn't realize you were from Spain until I saw some of your labels in Spanish.
@@TRONMAGNUM2099 You wouldn't even have to grab it internally. The +3 has RGB signals right on the monitor connector, so you should be all set. Not sure what's involved converting them to HDMI. Hopefully it's very simple.
Hello Noel, there is a schematic for the +3 PSU here hardware.speccy.org/hardware/Fuente+3-i.html
That's awesome. Thanks!
Dust inside the keyboard can stop these booting properly had it a few times .Sound on the plus 3 was never great but there are a few ways of fixing the audio .
Yeah, sometimes a key press get stuck and it won't respond to anything else. Stay tuned for the audio video where we look at it in detail and fix it :-)
My +2 (not +2a) had a faulty cassette deck so I removed it and replaced it with an internal 9v power supply, then I cover the large gaping hole with a square of plastic
Oh I want a picture of that! 😃
Did you clean the drive head?
It looked really clean, but I did. I might have done it off camera now that I think about it though.
At least the PSU was serviceable, unlike C64 ones 😢
The thermal fuse will be blown on the transformer - easy to bypass
Did you see if the transformer body had a thermal fuse, ( usually a black plastic part with 2 wires coming out ), not all secondary windings could be broken.
I didn't! But I honestly wasn't looking for it. Where would it be located, any idea? I'll have a look today.
I also find strange ALL the transformer be dead....
_"The last of the ZX Spectrums"._ How about the ZX Spectrum Next? 😉
Hahaha... that one doesn't count in my mind, but yes, I guess you're technically right :-)
LOL, Smartarse 😁
That transformer is repairable all you have to do is replace the thermal fuse that embedded in the Windings but the thermal fuse is just under the type just peel it back and it will be there
Maybe replace the failed drive with a Gotek? May be less authentic but oh so convenient.
Yes, that's my fallback case. I much prefer to keep them as authentic as possible, and have those kind of modern devices as add-ons. But yeah, if I didn't have a replacement drive I would totally use a Gotek.
That AY was awful indeed.
I'm curious if this is also the keyboard controller as it is on the Amstrad :-/
No, the +3 has an ASIC which handles the keyboard lines. If you can read diagrams, you can see it here zxnet.co.uk/spectrum/schematics/Z70830.pdf
Right. And the reason the AY sounds so bad is because the sound circuit on the +3 is incorrect. I'll make a followup video explaining that and fixing it.
@@NoelsRetroLab Hi Noel, do you need info about the sound fix? Guesser has a guide here zxnet.co.uk/spectrum/+3sound/
Thanks. I had some other info but I hadn't seen that particular page. I'm hoping to actually dig into why it's wrong and see the difference in the oscilloscope. If all goes well I should have something in a couple of weeks.
@@NoelsRetroLab Good luck with the repairs, I'll be looking forward to see the results. By the way, would you be interested in a schematic for the disk drive? I have one here sites.google.com/site/bertyfromdk/_/rsrc/1534322020479/home/speccy-amstrad-related-stuff/AMSTRAD_PCW_FD1.jpg
Actually you shouldn’t use oil on moving parts in electronics but grease and preferably silicon grease. Oils can be corrosive to plastics and most certainly rubber and tends not to sit in one place that long but leak out and through (that’s what they were designed todo :) )
That's true. I have lithium grease for that exact purpose. I don't know why I didn't use it 🤷♂️
I REPLACE THIS CAPACITOR ON MY SPECTRUM
where to buy your tshirt?
You can buy it here: www.latostadora.com/retrolab/zx_spectrum_logo/2873751 (although they seem to be out of all sizes at the moment).
Your problem can be the read/write head also
You mean physical damage to the head? I suppose so. It certainly looked fine visually, but who knows. I have quite a few of these drives that need servicing, so I might make an in-depth video on how to fix them.
@@NoelsRetroLab Not physical damage. As far as I know there is an ohm resistance to be checked for the read and write heads and you should be within a certain limit and if not then the head is cooked. I had to do this I remember for 1571 Commodore drives but you may want to check also for this drive according maybe to specs you will find in the service manual. You may try also to change the head with another one and see if that solves.
Do you didn’t Even repair anything
did you try more than 1 disk on the drive ? lol
Those drives are very very moody ... one disk might work wonderfully in one drive and fail on another... it happened to me a lot
You should try to format a blank disk to see if the drive responds....
I did try a few and none of them worked. But if I have a known working one and it doesn't work in another drive, there's something wrong. I should have tried formatting it, you're right. Because if I can format it and write and read to it, then it's 99% sure an alignment issue.
@@NoelsRetroLab Good luck ! :)
I just think that from a mechanical perspective those drives are pretty solid.
Please post a video if you end up repairing it.
99% of the drive videos on YT are about replacing the drive belt
@@fft2020 Will do. It's only my list of videos to make, so hopefully I can get to it in the next few months.
My computer has Coronavirus🤕🤧😵
Everything in this video is just 'for another video' nothing fixed just a video of destroying one computer to fix another .....