Can I fix this Sinclair Spectrum+ 128k?

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When TRU got in touch asking if I'd be willing to help with his ZX Spectrum+ 128k toaster well, its another machine I've not had much experience with so I was only glad to take a look. What turns out to be an obvious fault, sometimes these things do just need another set of eyes to be found.
Many thanks to Jonathan (TRU) for donating the diag cart, I'm sure that will come in very handy for the future.
CRG Twitter - / yt_crg
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Music by Banjo Guy Ollie - ‪@banjoguyollie‬
Thanks to MFMI and his discord for help with this one - ‪@MoreFunMakingIt‬
Chapters
00:00 Intro
00:14 Letter
01:58 A look around the Spectrum
04:28 Getting inside
06:57 Look what I found
10:37 Checking voltages, reset and clock
13:53 Looking for a video signal
15:08 First power on
15:36 Was it the short?
16:14 Keyboard test
16:49 Testing an old ram chip
17:48 Assembling the diag cart kit
22:05 Configuring the diag cart
24:31 Testing the diag cart
26:18 Conclusion

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Опубликовано:

8 июл 2024

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Комментарии : 52

@somethingpeculiarthistime 5 месяцев назад

Almost to 10k subs! Congrats in advance, well deserved!

@CRG 5 месяцев назад

Thank you, its getting close now with just 31 to go. A massive milestone for my little channel and one that I honestly thought would never come. Not there yet though so don't want to jinx it...

@Synthematix 5 месяцев назад

This was the best spectrum they made

@CRG 5 месяцев назад

As I said I don't have a lot of experience with these but it certainly appears to be well featured.

@ianneill9188 5 месяцев назад

Really enjoyed the video. Great spot on the solder bridge. I now have to use a magnifying illuminated headset to do all my solder work, and the inspection afterwards... otherwise nothing would ever work!

@andrewstewart5972 5 месяцев назад

The numeric keypad was never launched in the UK but the Spanish 128k version built locally had it as an option.

@SonicBoone56 5 месяцев назад

Woohoo 10k subs! Must be neat having viewers send in machines you have little to no experience with, means you get to learn things before you get one yourself. I wish all diagnostic hardware came with excellent documentation like this one did. The schematics are a great thing to have.

@CRG 5 месяцев назад

Thanks, yes it's fantastic to see the channel roll over 10k. It is great to have people send stuff in but it's not just about that, I'm genuinely trying to help people with the machines. The diag cart is a lovely donation and I'm very grateful for it. I'm sure it will come in very useful in the future.

@TerribleFire 5 месяцев назад

Nice one

@CRG 5 месяцев назад

Thanks, an easy fix but sometimes it's nice to get a simple repair.

@terosaarela4555 5 месяцев назад

A toast rack without the toast rack? Interesting… Looked like a switching mode regulator. Good job, Glen!

@CRG 5 месяцев назад

The owner took the toast rack off to save a bit of weight in shipping. But a nice simple fix which makes a welcome change from the more troublesome fault finding.

@digitalarchaeologist5102 5 месяцев назад

Second ever computer I had after the Acorn Electron - fond memories.

@CRG 5 месяцев назад

Another machine that totally passed me by. The only thing I remember about acorn systems was the BBC micros in school. My own route at home was the MSX then a master system then the Amiga. In fact just thinking about it the only time I ever used an Acorn system was the BBC micros in school, I've never owned or used any of their platforms beyond that. I probably should do something about that at some point.

@digitalarchaeologist5102 5 месяцев назад

@@CRG Interesting, I only new one person who have had a MSX and I've never touched one in the flesh so to speak. I ended up owning a couple of +2s after this one and also ended up with a SAM Couple before all the Amigas I had

@Retroguyuk75 5 месяцев назад

Great to see a spectrum video :).. Glad it was only that bridge, these 128k machines are rare and it's fabulous to see one back fully working. :)

@CRG 5 месяцев назад

Thanks, I enjoyed working on this one even if it did turn out to be a simple fix.

@NiTye357 5 месяцев назад

TPU is flexible and available in different grades too for 3D printing.

@CRG 5 месяцев назад

Thanks for the info, I must look into that stuff cause I can certainly think of a few use cases for it.

@LeftoverBeefcake 5 месяцев назад

@@CRG Also check out flexible PLA, it might be easier for your printer to handle, since some soft TPU types can squish out of your printer's extruder gears if the filament path isn't well constrained.

@Nukle0n 5 месяцев назад

If you use Prusa Slicer it's just "FLEX" because apparently the TPU you get for 3D Printing isn't actually TPU or something..

@Nukle0n 5 месяцев назад

@@CRGNeed to print it very slow, and it might be hard to do on a bowden style machine, they usually recommend direct drive.

@-IFFTI- 5 месяцев назад

Construction plywood from Sinclair is always a thrill. It's good that nothing died after the recap shorts. Another ZX ready! 👾👾👾

@noggin73 5 месяцев назад

Nice. Similar to a C64 dead test cart. Thanks for your suggestion about CPC/Farnell. They sent me leaded solder with no issues.

@CRG 5 месяцев назад

CPC Farnell hasn't let me down yet. I find the leaded solder flows better but just be sure to wash your hands well after using it. Not that I can say for sure but if any lead wears off onto your fingers its probable best to clean that off.

@Phil-Sands 5 месяцев назад

I love my Diag cart from Bytedelight, an amazing kit and a must have for anyone repairing speccy's. Great video as always!

@CRG 5 месяцев назад

I'm very grateful to have been given it and I'm sure it'll come in very handy at some point in the future.

@TheRealBobHickman 5 месяцев назад

Great catch. I can't blame TRU, I did something very similar when I upgraded my 520ST to a 1040. Despite having a lot of soldering experience I had inadvertently bridged a single pin, but it wasn't easy to spot if you've been looking at the board for so long. It took some fresh eyes to find it and they spotted it right away. I was a little embarrassed, but happy that my ST was working again and had 1MB finally!

@CRG 5 месяцев назад

Yeah, sometimes it just needs that extra set of eyes to catch the obvious problem. I've been down many a rabbit hole before looking for something more complex when the problem was actually something simple I had missed. So no blame whatsoever to TRU and if anything it gave me the opportunity to work on one of these lovely machines.

@MrFixiit 5 месяцев назад

Good work glen

@CRG 5 месяцев назад

Thanks

@evertonshorts9376 5 месяцев назад

Sometimes the best tool you can have is another pair of eyes.

@amanvasamantino5368 5 месяцев назад

Good job

@CRG 5 месяцев назад

Thanks

@vanhetgoor 5 месяцев назад

The world evolves while the ZX-Spectrum+ will stay put at a meagre 128kB of RAM. By now the RAM could have been doubled for almost no costs. Wouldn't it be nice to make a big step forward and enlarge the memory to 1 MB? Numerous extra playing fields could be made with eight times as much memory as before. Why would only Atari ST's and Amiga's dream in megabytes of RAM, the Spectrum is worth it!

@CRG 5 месяцев назад

I suppose its more just hitting the balance of amount of usable ram against what you can achieve on the system. I know the spectrum pages it ram but I imagine there is also a physical limit on how many pages it can address. Like anything though I'm sure there are ways around it if someone was determined to get 1024kB of ram into their speccy.

@kurbeco 5 месяцев назад

@@CRG it can be kinda done via an external cartridge with paging; ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-_SibY93sX0I.html that is up to 512KB. (for bonus fun, I'm sat at the front of this one :D )

@weepingscorpion8739 5 месяцев назад

Great job. These tiny bridges kinda scare me (too strong a word but...) when starting my own soldering escapades but I'm sure I'll be fine. I also love that diag cartridge. I believe you can also just keep it in and have a LED show while playing Speccy games. How cool is that?

@CRG 5 месяцев назад

The key here is to use flux, as you seen in the video a little bit of flux and the solder just flowed to were it needed to be. This type of bridge though is very uncommon as most boards will have a solder mask. I'll have to try a spectrum game with the diag cart installed, I wonder what type of light show it would display.

@weepingscorpion8739 5 месяцев назад

@@CRGI will definitely be getting and using flux. One project I would love to do is the Harlequin board and then use the Mechtrum case for it. I was inspired by Lee from More Fun Making It. One question I have about flux is that I won't be soldering things all the time and I have heard conflicting things about how long flux lasts, so is that actually a thing I need to look out for? Or is that not actually a thing?

@CRG 5 месяцев назад

I've had my 30cc tube of it for just over a year now and it seems to be fine. It is almost done now but I'll just buy another when I need it. If you aren't doing much though a 10cc syringe would do. For any though hole stuff though and for the most part you won't really need flux, the solder you bought most likely has a flux core and that's enough for 99% of through hole. I only apply a little flux if I need it on any though hole joints that are proving difficult.

@weepingscorpion8739 5 месяцев назад

@@CRG Thank you. I really appreciate it. :)

@Breakfast_of_Champions 5 месяцев назад

Good jobbie Bobby😀What does the "toaster" name refer to? Does it produce so much heat?

@CRG 5 месяцев назад

Thanks, its nice to get a simple repair like this every once and a while. The "Toaster" refers to the metal grill that is meant to be on the side of this machine. It sort of resembles a toast rack.

@2009numan 5 месяцев назад

how does it achieve 12 volts when its fed from a 9 volt power supply ?

@CRG 5 месяцев назад

Taking a quick look at the schematics the the 9v supply comes in via a coil which appears to step it up to 12v. There are a few transistors in the circuit too so perhaps they are doing some voltage doubling (for want of a better term). Power supply circuits are not a strong point of mine so I may be wrong but that's my interpretation of the schematic.

@electronicengineer 5 месяцев назад

@@CRG You are 100% spot on Glen. It is called a "Boost Converter", for future reference. In this case, a 5 volt to 12 volt step up in voltage. Thanks for your engaging videos. I quite well enjoy them! Fred

@Synthematix 5 месяцев назад

Inductor

@archivis 5 месяцев назад

@CRG 5 месяцев назад

👍

@hackbuildrestore 5 месяцев назад

Nice video, you do a nice soldering montage!! The spectrum fix was a very good example of Occam's razor @GadgetUK164 would be proud !!

@CRG 5 месяцев назад

Thanks, glad you enjoyed it. Certainly an easy fix but absolutely one of those things you could easily get dragged down a rabbit hole of looking for the problem elsewhere.