Let's service this ZX spectrum!

On the bench a ZX Spectrum in need of TLC!
Thanks PCBWay for sponsoring this video: pcbway.com/g/M525r4
Previous ZX Spectrum video: • A Very Faulty ZX Spect...
External ROM project: github.com/konkotgit/ZX-exter...
OTLA: code.google.com/archive/p/otla/
Retroleum: www.retroleum.co.uk
00:00 Intro and overview
03:17 Powering up
05:21 Trying to fix the keyboard
12:16 Power draw test
13:56 Capacitors!
15:25 Power draw test 2
16:13 External ROM PCB
17:54 Final MODS
20:11 Video output adjust
22:08 Membrane replacement
25:51 Burnt resistor?
27:32 Software loading
30:33 outro

[@peddersoldchap]

8:10 Thanks for leaving on the mistakes; it's a useful warning for those trying to do repair work.

[@tony359]

No worries - it would be boring if everything went smoothly :) Thanks for watching!

[@bitsundbolts]

Great restore of the ZX Spectrum! I always wanted to do a measurement of bad caps vs good caps from the power supply. But I never had a board where I would dare to power it on with the old capacitors still in circuit.

[@tony359]

Apparently I pushed my luck here :) oh well, it worked! :)

[@minombredepila1580]

Very nice service and relaxing video for the end of the day, Tony. I didn't know about the 5v regulators, to substitute the "oven" 7805. Heard about the "Traco" ones but they were not cheap, and retroleum sells the one in your video for lower prices. Cool !!. I guess this is the time to service my Speccy.

[@tony359]

Retroleum has very good prices and reasonable shipping indeed. These regulators should be very similar to the Traco ones. As much as I like keeping things original, in this case it’s really a good thing to turn off the oven 🙂

[@rodneylanders5985]

Keep up the great work,Tony ! Totally enjoyed this video

[@tony359]

Amazing thanks for your comment!

[@Thorsten369]

Great video Tony and as always it brings back some good memories. Keep up the amazing work my friend ;)

[@tony359]

Thank you!

[@jb2590]

Thanks for another great video Tony :)

[@tony359]

My pleasure!

[@RetroPC-vy3kt]

Really nice restoration, she'll have years of fun with this now.

[@tony359]

Fingers crossed! I hope the modulator works! :)

[@didiertoulouze8156]

I spend so much time on my Spectrum programming Basic (and play Manic Miner). Thanks for this restore :)

[@tony359]

Back in 1982 it was like magic! Thanks for watching!

[@general23cmp]

Great video!

[@tony359]

Thanks for the visit

[@thealphageek1975]

Is it just me or did the video quality improve too after the capacitor replacement? Love this!

[@tony359]

It's a different capture device, an old Elgato which doesn't work with anything BUT the ZX Spectrum! Thanks for watching!

[@tiemanowo]

28:35 It always fascinates me how many different types of data storage was invented for computers. Like: sound, mechanical (punch tapes), magnetic, light, electric and propably many more I don't even know.

[@tony359]

Yes, back then when any small option was a good one!

[@SpeccyMan]

were invented, (plural please)

[@tony359]

I'm now expecting an email with a long list of grammatical mistakes I made in this - and all my other - video/s :) 😜 I do pick most of them during the editing phase but its(*) part of the show! 🙃 I think the funniest one was "Now grab your balls" when referring to the solder balls in my BGA reballing video! 😄 (*) intentional 🙃

[@BumdanglerFartbiscuit]

@@SpeccyMan Capital letter and quotation marks, please.

[@jeremiefaucher-goulet3365]

Awesome video ❤

[@tony359]

Thank you!

[@aleksandardjurovic9203]

Thank you very much for this entertaining video!

[@tony359]

You are very welcome, thanks for watching!

[@Senux-Video]

Thanks for video. zx - my childhood. For retro pc's keyboard rubber repair I use Circuit Breaker Repair, the same loctite 3863..

[@tony359]

Great to know, thank you!

[@LuisFCorreia]

I have in my old spare parts bin a "deaf ULA" which was damaged around the 90's but kept because it still produced video and worked great for testing and debugging. (i'm also a sucker for old hardware which is partially working)

[@tony359]

I would do the same! A half-broken ULA for testing, amazing! Too bad the other one did not survive! Thanks for watching!

[@AramAzhari]

The very first device I ever laid my hands on, at the age of 6. My sibling taught me to type a print command and then save it to an audio cassette 😄. 34 years later, I work as a software developer for a large corporation 🤠

[@tony359]

Amazing, that's the way!

[@SpeccyMan]

And yet you cannot spell laid? 😉

[@AramAzhari]

@@SpeccyMan good catch! I fixed the typo. Thanks.

[@tony359]

@Speccyman - everybody is welcome here but I really have to ask you to refrain from adding so many comments about grammatical mistakes or misspells on the comment sections. You are welcome to participate, comment, criticise but I really don't see the reason for adding so many comments whose purpose is only to highlight other people's mistakes. I appreciate your help on this, thank you!

[@Epictronics1]

Coming from a C64 childhood, these machines are so tiny! Nice restoration!

[@tony359]

Yes! They look like toys but they're not!

[@SpeccyMan]

The beloved Speccy was very very very temperamental about levels on its mic socket. I do believe there is an Arduino based hardware solution (I can't for the life of me remember what it is called) that allows you to play tap/tzx files - stored on an sd card - into a Speccy. Certainly a worthwhile investment if you are servicing a lot of the machines. It is heartwarming to see the old machine getting some TLC and being restored back to its former glory with no corners being cut in the process. 👍 And yes, my screen name is a tribute to the machine. 😉

[@tony359]

Thank you for your comment! I don't have more Speccy's for now so the laptop will be ok for now but I'll keep that solution in mind, thanks! Thanks for your kind words!

[@Snowsea-gs4wu]

3, 2, 1 go. Awesome!

[@tony359]

I'll have to make some shirts one day :D

[@pepealexandre]

Awesome!

[@tony359]

Thank you!

[@I_Don_t_want_a_handle]

Oh, the hours spent in the early 1980s fiddling with the tone and the volume of the cassette player for every game ... and all I had to do was click off 'audio enhancements'. 😆

[@tony359]

I'm sure Windows 3.1 also had a similar option! :D

[@crazyedo9979]

My first thaught seeing this bottle of super glue: Watch out for the contact side. 😁

[@tony359]

🤦‍♂️ The definition of clumsiness :) Thanks for watching!

[@CodingSync]

Electrolytic capacitors contain wet chemicals that dry out. They also have a rubber bung at one end to allow for safe leaking out of the chemicals rather than an explosion due to boiling. And the cap may have indents on it to allow the case to split. So they lose their ability to act as a capacitor for smoothing out ripples on power rails and storing energy to satisfy the demand of pulses of current required by the circuits. It is a very good idea to replace old E-caps on power rails.

[@tony359]

It never hurts, yes! Thanks for watching!

[@piernov]

Silver conductive paint can be used to fix traces on membrane keyboards. However depending on the keyboard (I don't know about these specifically but doesn't look too bad) it may not be a fun job to do and it can be difficult to obtain a nice result. So it can still be a better idea to get a replacement keyboard/membrane if they are available for an acceptable price.

[@tony359]

Exactly, I think the membrane was £9 and it's "plug and play". Sure, with silver paint you can fix many membranes but that's assuming the rest of the membrane is working :) Thanks for watching!

[@piernov]

@@tony359 at that price it's indeed a no-brainer when you're doing that for a customer. I have fixed a handful of laptop keyboards with silver conductive paint, with damaged traces (or even contact pads, but these are harder to get right) inside the membrane, but I definitely understand nobody wants to go through the trouble. I wish it was as easy to get a replacement membrane manufactured as a PCB though.

[@nickolasgaspar9660]

I always use double sided tape to reinforce the ribbon cables with plastic pieces.(mainly because of my unjustified fear of unwanted reactions between the liquid glue and plastic). That would be helpful in the case of the error you showed. As much as I love Speccy, I really hate the way it was built. To many ways to make an error and break the computer. To many asterisks when swapping ICs between different issues. Far to many ways to have your RAM cooked. I really enjoy Jay Miner machines of the same era, you just can't go wrong no matter how inexperienced you are.

[@tony359]

yes, those machines were horribly built - you really need to bear in mind they were < £100 to appreciate how cool they were! :)

[@markretro3612]

OTLA is a great loader .. very fast but can be the tricky on the levels as you found out

[@tony359]

What would you use? I tried playing WAV files or an app on my mobile but that didn’t work.

[@markretro3612]

@@tony359 yeh wav or mp3 files, i use WINZTX to transfer them from ztx files etc. the laptop output is the weak point but if you are able to load OTLA then a standard loader should be no problem. once you have them as audio files you can also try other devices like iPhone etc. i even import them into my iTunes library. also the issue 2 spectrum are the most difficult to load from. what cable configuration are you using ? ie the spectrum end needs a mono jack but the device loading needs to be correct for that device

[@tony359]

I manually patched the jack output to the ZX as - as you said - it's stereo and the receiving jack doesn't like it. It's weird as OTLA works but VLC doesn't. I didn't try after realising that I had a compressor on the line though.

[@franktriggs]

That board plugged into the chip socket is from a Foxx 32k upgrade kit. I have the exact same issue 2 16k spectrum with a Foxx memory upgrade. Also, it should have grey keys for a 16k model.

[@tony359]

Ahhh interesting. What is a "foxx 32k" kit?

[@franktriggs]

Foxx was the name of the company that sold the 32kb memory upgrade for issue2 speccys, I got mine for Christmas in 1985@@tony359

[@tony359]

So you're saying this ZX was born as 16KB and then upgraded via Foxx upgrade, not Sinclair's? And the keyboard is not original?

[@franktriggs]

It was sold as a Sinclair 16kb model yes, then upgraded by someone later. The issue 2's had sockets for the RAM and logic chips to upgrade it. Most old 16kb had grey keys, a few later ones had the blue keys, Sinclair probably just used up the grey's then used blue. So it may be original.@@tony359

[@nickolasgaspar9660]

The conductivity issues of the ribbon cables can be addressed with conductive paint. Unfortunately its a really common problem. (with Atari membranes too).

[@tony359]

Yes, I could have tried that though the replacement is not so expensive so... but definitely a tool to keep on your desk!

[@sarkasaa]

at 24:29 was that GOSUB on the H key on purpose? 😆

[@tony359]

Oh, I just got it! 😆

[@peddersoldchap]

29:30 HAHHHAH RIP scope XD

[@tony359]

To be fair, it's my network :) The scope is good, it keeps working but there is something with the rest of the network which upsets the VNC every now and then! Thanks for watching!

[@harvaldi]

I'm always conflicted if it is better to restore/leave original state of retro machine or upgrade it in some way to make it more reliable, functional, better. After all how many of these machines could get original parts?

[@tony359]

I like to keep things original as well, in this case keeping it original means to really shorten the lifespan of the unit IMHO. Thanks for watching!

[@jameshearne891]

I wonder what they managed to plug into the tape port to overheat that 10K resistor Assuming it's a quarter watt (it could be half) resistor you'd need 50 volts just to dissipate the 1/4 watt and a lot more to actually cause it to overheat that much.

[@tony359]

Yes! I'm thinking that someone might have plugged a speaker line. Still, to provide much more than 1/4 watt... I don't know! Thanks for watching!

[@jeremywh7]

What is the current draw range now, after the voltage regulator upgrade?

[@tony359]

Ah, I didn't really check that, good point. I'd imagine it lowers a bit.

[@za_ozero]

That resistor was red hot at some point

[@tony359]

Oh yes, I guess some magic smoke escaped too!

[@valterstrumpiks7832]

Retro stuff is great, but is there a way for you to take on a more “conventional” products from time to time? You know, the boring stuff, fixing a car audio amplifier or a more modern game console? Would do great for views and attracting more audience. Superb production by the way, really enjoy watching your videos! Just to be clear, I know you have videos about PlayStations of many generations, they do get good views hence my comment.

[@tony359]

Wellll… my last PS3 video didn’t go so well! Fair enough it was a simple repair. I always welcome new stuff. More modern devices might be ‘too small’ for me to work on. Some modern SMD stuff is crazy small and I’m not sure I’d enjoy that. But I do have many things on the pipeline, amplifiers, sound processors, PS4… the difficult part is to get to them but they are on the list! Thanks for the feedback and for watching!

[@LuisFCorreia]

Hey Tony, saying it again, you should NOT power on an ancient Speccy without changing capacitors first. You are risking damaging lower RAM from spikes that occour on power on

[@tony359]

I'll bear that in mind thanks!

[@sokoloft3]

Classic windows messing with audio settings. Such a pain. I use voicemeeter banana and some updates change my output device.

[@tony359]

Windows has been resetting my HTPC audio settings with updates since I can remember. It's so annoying!

[@MK-jo1gi]

That shows how incredibly cheaply the ZX Spectrum was created. It's an impressive piece of engineering for it's time, but man some of the things are nasty. :)

[@tony359]

Aren't they! :) For 1982 though Sinclair managed to develop an incredible machine!

[@bradallen8909]

@@tony359Not really when you consider the C64 also launched in that year.

[@tony359]

Yes but the C64 was launched at $595, the ZX spectrum base version at £125 (around $220 back then)

[@bradallen8909]

@@tony359 Yes, I realise it was built to a certain price point. But you get what you pay for. The graphics on the Spectrum are nothing short of laughable.

[@SpeccyMan]

... its time ... (no apostrophe in the possessive pronoun!) 😉

[@AttilaAsztalos]

8:10 Clearly, attention to detail died in the eighties. This is how off-by-one bugs get normalized - "moreorlessthanorequaltooneorzeroorminusonewhocaresit'scloseenough"...

[@tony359]

You mean the silly keyboard flat cables?