Sinclair ZX Spectrum +2 Repair

[@backtogeek]

Nice one, I never would have given it that much time so I am pleased I sent it over to you for many more happy years in circulation!

[@JanBeta]

Thanks for donating the machine! Years of fun (hopefully) to come. :)

[@jaycee1980]

6:25 Technically the modulator is different - unlike the original spectrum it is driven by TR1's collector, rather than an emitter follower type amplifier (TR2 in a 48K). The best way to get composite out of a +2 is from the RGB connector, or you can attach a wire to LK4 which is the 75 ohm terminated composite output that goes to the RGB connector. Don't make the mistake of connecting a clip to pin 6 of the TEA2000 - this will burn it out as it's not made to drive a 75 ohm load ! I've made that mistake twice now, fortunately Ian Gledhill saved my ass by selling me a few new TEA2000s :) When it comes to the RGB output you should check R12-R14 and D9-D11 are fitted. Some +2's dont have those and they output a TTL RGB signal as a result. Fitting those parts will give you an analogue RGB output suitable for use with a SCART input. You should also find LK4 and LK8 fitted - giving composite out on pin 1, and audio on pin 3. I think LK3 should also be fitted which gives +12V on pin 5.

[@chinosts]

Thanks Jan for always being awesome!

[@JanBeta]

Thank you! :D

[@arfanmedni7294]

RIP Clive Sinclair, gone to silicon heaven.

[@TheRetroShack]

Just got one of these in to repair, so a timely video Jan - thanks! (Lab looking good btw!)

[@JanBeta]

Ha! Thanks, hope the video is useful. I can definitely recommend the Diagnostics I used. Very handy. :)

[@ojbeez5260]

I threw a +3 in the skip back in the day (given to me broken) but I recently rescued a +2 from being recycled, had the same/similar fault. So it has helped on with my psychologically recovery of the traumatic event of my own stupidity those many years ago! :P.

[@JanBeta]

So your Speccy karma is cleared now. ;)

[@Ladefuss]

Another great video Jan. Thanks. And really great that we can see you now in person instead of just watching those skilled hands working :)

[@JanBeta]

Thanks, glad you liked the video. I try to make more appearances recently, feels more natural I hope. I am still kind of camera shy but it got a lot better.

[@evrieze]

I have also made such a testROM which has been useful for repairs. The W27C512-45Z EEPROMs are excellent for that purpose and you can use them as drop-in replacements without any modifications. It is the top half of the 64kB space to be programmed. Many have discovered the nice features of these Winbond EEPROMs.

[@nickjnow1]

Great video. I used to have that model and spent many hours playing. Rainbow Islands was the best. I have a little daughter who noticed Fluttershy in the background.

[@JanBeta]

It's a lovely machine for sure! Fluttershy was a gift from my kid. :)

[@stephenvalente3296]

Thanks for all your videos Jan. Whilst I may not always understand some things, or ever own some of the machines you work on, love watching them. Joy to watch, and natural instead of being one of those content providers who comes across as condescending and probably cutting out any minor mistakes to look perfect every time. Real life isn’t always perfect.

[@JanBeta]

Thanks for the kind words! I always try to show the mistakes and make the videos in a way that feels natural (well, mostly they are natural, I'm not a good actor anyway...). :)

[@TanjoGalbi]

That was the first of the Amstrad versions of the Spectrum after Amstrad bought out Sinclair. The last true Sinclair Spectrum computer is the ZX Spectrum 128k Plus model, known as "the toast rack Speccy". The included tape deck is an Amstrad design choice.

[@ojbeez5260]

True - see my more in-depth comment.

[@cjmillsnun]

True enough, but the motherboard lineage is still there and it shares the ULA with the toastrack. The +2A and +2B were very different beasts

[@Daz555Daz]

I agree but it is worth saying that the +2 is a lot more Sinclair than the +2A onwards though. The +2 is really a reconfigured toastrack but the +2A onwards had a lot of Amstrad changes - most of which were unwelcome.

[@cygil1]

Well if you want to be pedantic the spectrum 128 was designed and manufactured under license by the Spanish Ivestrinica and this doesn't count as a true Sinclair spectrum either.

[@TanjoGalbi]

@@cygil1In collaboration with Sinclair Research so yes it does. "In 1985, Sinclair developed the ZX Spectrum 128 (code-named Derby) in conjunction with their Spanish distributor Investrónica. Investrónica had helped adapt the ZX Spectrum+ to the Spanish market after the Spanish government introduced a special tax on all computers with 64 KB RAM or less." - Wikipedia (Yeah I know, but they are a good source of facts in most cases)

[@SaintKaede]

And this is why I watch Jan to see computers I would not normally get a chance to see anywhere else and learn somethin' new in the process, Danke Jan!

[@JanBeta]

You are very welcome! I love exploring new machines from time to time. :)

[@vusumuzimbanjwa1189]

I am Vusi from Durban . You have just reminded me of my ZX Spectrums 48K and my Commodore 64. after that there was a Spectrum QL 128 which had an audio cassette mechanism for playing and making games. I do remember ZX selling micro cassettes for games. but I was using mine to label wedding videos instead of writing on paper using a modification on the RF box and connecting a signal to a recorder. it took hours to write the bride and grooms name be cause a programing language used then was very difficult. The language was BASIC (Beginner's All Purpose Symbolic Instruction Code) I did that because I could not afford an AMIGA which was a dedicated computer for videographers.

[@Chrispynutt]

Cool, this was my childhood Speccy, never had a working joystick port so keyboard for me :)

[@VHSBits]

The joystick ports on the +2 are a pain as they aren't Atari compatible but have the same socket, maybe something gets damaged if regular joysticks are plugged in?

[@JanBeta]

Yeah, they shuffled the pinout around so they could sell their own joysticks with the machines I think. I don't know the pinout off the top of my head but it might very well be that the 5V supply gets shorted in certain positions. :/

[@ojbeez5260]

@@JanBeta It wont short the 5V because Amstrad and spectrum do not have - unlike the C64 Sega Megadrive Gamepad death warrant!! Also, the same ground (pin 8) on both they just swapped around UDLR and fire. Hence, joystick would sort of work but go in different directions or not at all. They would not make it so that it could short because otherwise lots of people would plug in an Atari style joystick and Amstrad would have got lots of 'returns' back in the day. Yes, Amstrad wanted to make more money out of proprietary Joysticks but companies such as the one that made the Cheetah 125+ just had an extra (Grey) Cable for the spectrum +2. Also , as with the Amstrad, I believe the polling interrupt for the Joystick is from the Keyboard. Hence, to get auto fire working you need to use a 'quadplexer' chip to prevent the 0.02 seconds polling interrupts from the keyboard stuffing up the autofire and supply 5 volts to it in addition to the 'autofire' circuitry inside the Joystick or from an autofire you make yourself out of a 555 timer chip or the like. So you need 2 blocks of circuitry to get autofire to work. One with a 555 timer chip (hopefully provided by the Joystick) and one with a quadplexer chip with independant 5V power supply. Quite a job.

[@RetroHackShack]

Great timing! I have one in the garage that I need to work on.

[@parrottm76262]

Another great video for a system I was not familiar with. Thanks for that! Always want to expand my retro computer knowledge.

[@JanBeta]

Glad you liked it. I love exploring new machines. :)

[@KJohansson]

I have a few rough machines (a SVI-728 and a Thomson MO5) that I need to work with, this is the sort of inspiration I needed! Excellent video! :)

[@brendonelton]

Always great to see another ZX Spectrum come back to life :D

[@JanBeta]

Glad I could fix it! More tinkering with this to come very soon. :)

[@SidebandSamurai]

Love your videos. The pointy bit is called an awl. Pronounced "all" as in "they all came over". Thanks for showing us the ZX Spectrum +2. All the cool little computers that were sold in Europe that we did not see here in the states.

[@JanBeta]

Thanks! The awl thing got pointed out to me in a previous video but I mangled the word up in my brain. :D

[@SidebandSamurai]

@@JanBeta Its the German part of your Brian taking over. Pointy thing works as well.

[@discoHR]

02:00 These are opened like a book. Lift the right side, disconnect a cable in the middle then flip the top case over to the left of the bottom case. No need to unplug the keyboard cables. Same goes for Amstrad versions of +2 and +3 and also CPC 464 and 6128.

[@JanBeta]

Makes sense! I'll try that approach the next time. I was a little confused by the cables but it turned out to be less entangled than I initially thought... :D

[@OrencioRamirez]

Thanks for your videos Jan!

[@JanBeta]

You are very welcome! Glad you like them! :)

[@admirerofclassicalelectron2858]

I like the Speccys because they always have to be repaired. Most time the failure finding is rather easy and a good exercise.

[@oliver1224]

Really nice work there. I used to have that very spectrum model. Brings back memories.

[@JanBeta]

Thanks! Full restoration of this Speccy coming soon. :)

[@GeorgeEI7KO]

I had a +2A back in the day. Atari ST after that.I like your Scope Jan. Very neat...

[@jaycee1980]

Also just remembered something - on these machines the audio carrier is coupled into the composite video signal... this can cause distortion on the video, i could see it when you were entering a BASIC program and pressed ENTER. The fix for this is to remove C31. If you want to keep the RF output fully functional, you need to wire a replacement C31 (20pF, 22pF will work fine) so that it connects pin 4 of IC11, to TR2's collector. There is sometimes even a pair of pads on the board marked "C31" for this.

[@VHSBits]

Nice to see a video on the original +2, this was my first computer and I still have it. I just recently treated it to some new capacitors and figured out that it had the backwards transistor issue which I also fixed. I gave it some new belts and a new PAL chip that fixes a bug - not sure if it's really necessary but nice to have it work as it should.

[@JanBeta]

It's a very nice machine overall. I have yet to read up on the transistor issues, I think they just used transistors with a different pinout originally and never bothered changing the silk screen or program the pick and place machines correctly... Didn't hear about the PAL chip issue but I'm going to look into that, too.

[@jaycee1980]

@@JanBeta for the PAL chip Google "spectrum unrainer". Basically it solves a display corruption issue caused when the CPU accesses contended memory during an interrupt. It's also a good way to program a replacement 16V8 GAL should the original PAL fail :)

[@jaycee1980]

Just noticed you have a new oscilloscope :) I recently got a Siglent SDS1104X-E to replace my old Tek 2213A. It's amazing how much better a DSO is :)

[@thebilecollector]

I've had a couple of these since I was a kid, I've always found that the tape deck buttons break and fall inside with these, I used half of a clothes peg to lever the mechanism inside to work, that was my fix haha

[@ojbeez5260]

I love ghetto fixes like this...reminds me of the blu-tak wobbly ram problem with the zx81

[@thebilecollector]

@@ojbeez5260 I still have my half peg ready for whenever I want to dust off my speccy to this day lol. Thing is it works perfectly and because it's wood I feel like it's a bit softer on the plastic pieces inside. The tv out or power supply, one of the those connectors is a bit dodgy now though unfortunately

[@deano7649]

Great video as usual Jan ! I used the DiagROM on my grey +2 last weekend and had the same RAM Fail 4 error. Piggy backed the new RAM chip to get it working but forgot to order some DIL sockets for the new 4164 so thats my next job. Keep the great videos coming, will be nice to see a follow up video for this machine :-)

[@JanBeta]

Nice! The DiagROM is a great tool for troubleshooting these machines indeed. Glad it helped you, too!

[@nor4277]

Jan beta there is a spray for belts on cassettes etc,belt grip spray it on let dry then bad belts grab better,I think they also have one for car belts too.it will buy you time while you are waiting on new belts.

[@MichaelOglesby]

Nice work. Looking forward to more in this series.

[@JanBeta]

Thanks! I think there is going to be another video about the Datacorder at some point. I ordered a new belt already.

[@up2tech]

Thanks Jan Beta for show how to fix my favourite computer :)

[@wettuga2762]

Very informative video! I used to have a Timex 2068 but got "lost" somewhere while moving between houses. Now I have a Timex 2048 and a ZX Spectrum +2. Last time I powered on my ZX Spectrum +2 it didn't work, only the power LED would light up and nothing else. Since I don't have any electronics knowledge and at most I know how to do basic soldering, I might start by replacing the voltage regulator, reverse the 3 video related transistors (if needed to) and go from there. I do like the memory test method using the 27C512 eprom, does it also work with the Timex 2048?

[@JanBeta]

I’ve never worked on a Timex version so I’m not 100% sure if the EPROM is going to work but given how similar the machines are it will very likely just work without any problems. Hope you are going to be able to find the fault! If one of the main chips is broken, troubleshooting can be tricky on these. I recommend also checking the Z80 processor, the older variants often break but you can replace them with newer Z80s without any issues. Best of luck!

[@EviesRevue]

Nice! I picked up one of those +2 Spectrums recently.

[@JanBeta]

Nice! They might be my favorite Speccy models (well, I'm going to see after refurbishing)... :D

[@battmann7089]

Nice video as always Jan .This was my very first computer and I have a lot of nostalgia for it. Mercifully I still own one. I don’t think the +2 was anything design wise to do with Sinclair the honour of last true Sinclair machine in every sense goes to the toastrack 128. I’m pretty sure the grey +2 was an all Amstrad machine in every sense but compatibility wise very comparable to the toast rack. If I’m wrong in any of that I apologise unreservedly!

[@JanBeta]

Thanks! I guess I misread the Sinclair/Amstrad thing. Probably it was only based off the Toastrack board design and the rest of it is pure Amstrad. At least the looks of it are not Sinclair-y at all. :D

[@battmann7089]

@@JanBeta To be fair to you Jan I might know about that particular part of Speccy history but if you got me to try and do what you do to fix them and many other machines- I’d have absolutely no clue! Love the videos mate, keep up the great work👍

[@nerdygeezer78]

Really enjoy watching your repair vids.... keep em coming

[@itselfbookshelf8472]

might pick one of these up, better than the original Spectrum with its rubbery keyboard

[@desfarren7890]

Thanks Jan great vid as always I was just starting on Zx 128 +2 the Diagnostic Rom what a great help.

[@JanBeta]

Thanks Des! The DiagROM is brilliant. I used the tape version of it before but wasn't aware it could be used in an EEPROM until Brendan pointed that out to me. :D

[@TRONMAGNUM2099]

Nice scope!! You should do a review of it.

[@giuseppelavecchia775]

Bentornato jan,sono molto contento di vedere il tuo ultimo video.sei mitico.

[@hucky29]

brilliant. love my speccy 128k

[@KopterSD]

Hallo Jan ich schreibe mal in deutsch, woher bekommt man so schöne Geräte? Ich bin seit Jahren auf der Suche nach einem bezahlbaren C16/PLUS 4 mit Zubehör, unmöglich. Viele Grüße Uwe.

[@JanBeta]

Dieser Speccy war eine Spende aus England. C16 und Plus/4 werden leider immer rarer, weil die Chips so häufig sterben. Ich habe einen Plus/4, den ich vor Jahren mal günstig bei eBay gefunden habe (als die Retrowelle noch nicht ganz so massiv war). C16s habe ich einige defekte gespendet bekommen, musste dann allerdings Prozessoren und TED Chips kaufen, die beinahe genauso teuer gehandelt werden wie die kompletten Computer. Ist leider extreme Glückssache momentan. :/

[@KopterSD]

@@JanBeta danke für die Antworten, bei uns in Dortmund, Binarium steht noch ein Plus 4. Übrigens du machst einen guten Job und ich finde deine Art und Videos echt cool, Viele Grüße aus Dortmund, Uwe

[@FernsDad]

Great video. Thanks

[@SnerkleBurger]

Love Speccy content. Thanks Jan. =)

[@mauricelelapin3754]

hello, thank you very much for your video since I'm trying to fix a grey Spectrum +2 with the same glitchy screen but I have strange issues : power is ok, cpu and ula get hot, the main heatsink also get hot, I have checked the voltage at some points on the motherboard and it is a little below 5V. I have not found any of the lower RAMs being hot. I have burned ZX Diagnostics on an Atmel AT27C256R DIP28 EEPROM, since its 32Kb I used your "copy" trick to create a 32Kb by copying twice the 16Kb testrom.bin file ;) but ZX Diags do not launch and I end up with the same glitchy screen :( is the problem linked to the Atmel EEPROM not compatible ? Two things I noticed is that : 1) when there is no ROM chip in the motherboard, the reset button DOES work but it doesn't work when the Amstrad or the ZX Diags ROM inserted 2) when there is no ROM chip in the motherboard, I have a nice color filled square around the screen displaying the random graphics chars I wondering if the failure is not RAM related but somewhere else that prevents / fails the Spectrum to read / access the ROM ? Help / Clues very welcome ! thanx a lot & best regards

[@honoredshadow1975]

Does that look like someone has fired darts above the keyboard? Like little holes? I had the same ZX Spectrum model and I had it near a dart board and as a child I missed and hit the keyboard area and case. Also my ZX Spectrum had the exact same break in the plastic of the tapedeck. Spooky...

[@JanBeta]

No dart holes in mine. It's just plenty of dirt sprinkled all over the case. I just double checked.

[@jamesdetenbeck6910]

This was awesome. Thanks Jan!!

[@jaycee1980]

2:20 I knew that rubber block was going to be the rattling thing... those always come off !

[@R.Daneel]

Off from where though? Just on top of a chip for keyboard support?

[@MrClump]

That rubber block falls out of every +2 I have ever taken apart and I still have not figured out where to replace them!

[@ojbeez5260]

@@MrClump They just did it to confuse people - I bet!

[@davidpickford4535]

Great video! Is the 27C512 EPROM a simple drop in replacement for the Spectrum +2 ROM?

[@JanBeta]

Thanks! 27C128-512 are drop in replacements, yes. I just used the larger EEPROM because I had it at hand, I duplicated the contents to fill the whole EPROM.

[@davidpickford4535]

@@JanBeta Thanks! I was missing the "duplicate contents step". Working like a charm now

[@kuro68000]

Another interesting video. Can I make a request? Can you make the into tune a bit quieter? It's louder than the rest of the video.

[@JanBeta]

The intro is approximately half the volume of the rest but the frequencies are a bit harsh on certain playback devices (it was recorded directly from a slightly broken C64 SID chip). I am working on refining the intro at the moment, I'll try to smooth the sound out a bit. Thanks for pointing that out!

[@kuro68000]

@@JanBeta Thanks. To my ear it sounds like it is in the human voice range so probably gets amplified by my soundbar's "clear voice" feature.

[@RDJ134]

Dont try this at home, this is my pokybit!! This should be a T-shirt slogan :) Great video as always.

[@2008Overkill]

This is first Amstrad Speccy, a kind of copy of the 128k (toast rack), then Amstrad brought out the black A and B that was cheaper to make, but less compatible. I'm sure Sinclair didn't make any of these, Clive would never go for a proper keyboard :)

[@JanBeta]

I read somewhere that there are some variants of this that were produced by Sinclair but I have never seen one of those in real life. Not a Sinclair/Amstrad expert at all though obviously so you are probably right!

[@ojbeez5260]

@@JanBeta The Grey Amstrad Speccy is based heavily on the Spectrum 128k by Sinclair. It's very similar. The later Black ones are more similar to the +3 and have lots of the typical doubling up of component functions for cost reduction as seen in many Amstrad products such as HiFi's etc. It is possible that Alan Sugar could have produced the +2 immediately after purchasing Sinclair at the same place where the 128k (by Sinclair) was produced and then moved operations (to reduce costs) to his own manufacturers shortly afterward. I've never seen one or if they even exist?!? But the in-built tape recorder is an Amstrad philosophy not a Sinclair one for sure.

[@jaycee1980]

It wasnt really that the +2A was cheaper to make, it was that the +3 had some extra targets - CP/M compatibility and a disk drive. The ULA was replaced with a custom gate array which was based on Sinclair's design specs for the 128 - which turned out to be incorrect in a few places, one of which was which banks of memory were contended. Most of the compatibility issues come from that. Meanwhile the ULA was manufactured by Ferranti, and by 1988 it had been sold off to Plessey and was being wound down because ULA's were dying out in favour of gate arrays. Amstrad made a fairly reasonable choice to move away from obsolete technology (mind you, the spectrum itself was becoming obsolete by then too!)

[@ojbeez5260]

@@jaycee1980 They used the same plastic and same PCBs for +3 and +2A and B , I believe. So, overall it was cheaper. But to get disk drive working you needed the extra hardware, true. But if your going to make a +3 might as well make the +2 as similar as possible to +3 to reduce overall manufacturing costs - just different case , same plastic (Black) and PCBs (less a few components).

[@jaycee1980]

@@ojbeez5260 only for a little while were black +2s (+2A) made by +3 boards without the disk controller parts stuffed... they did have their own cut down PCB later (+2B).

[@KolliRail]

Well done!

[@JanBeta]

Thank you sir!

[@evensgrey]

As soon as the system wouldn't come up from the on-board ROMs, I wondered if there was a diagnostic ROM like there is for the C64, and there it is.

[@JanBeta]

Yes! And it is way more stylish than the standard C64 diagnostics, too! :D

[@siriokds]

Perfect! Let's go with recapping.

[@JanBeta]

Yes, coming up next. :)

[@rdoetjes]

I wonder, will Clive Sinclair go into history as the man who couldn’t build a computer with a proper keyboard? This one is actually from the Amstrad era Allan Sugar was not shy of skimping on quality and esthetics either, but at least he wanted proper functionality for the “Lorrie driver and his missus”.

[@octaviussludberry9016]

3:29 Where you getting a little bit excited there Jan? 😆😆

[@ianstorey1521]

Nice new scope

[@JanBeta]

Yes! More about that soon. ;)

[@ianstorey1521]

@@JanBeta I can't wait. I'm thinking of getting a new one myself.

[@KaroKoenich]

That RAM fail message on screen was a little bit small. Hope they make it slightly better to read in the next iteration :-).

[@JanBeta]

Haha, indeed. I think it's deliberately huge so you can still read it when the screen RAM is nearly completely destroyed. :D

[@scaperlee]

Haha...could listen to your voice all day haha

[@JanBeta]

Thanks, i guess. :D

[@stephenvalente3296]

The Traco voltage regulators seem to be well regarded. Not cheap parts, but what is these days!

[@JanBeta]

Yes, I think they are very good. I have used RECOM switching regulators before, they are even more exepnsive than the Traco ones but they are definitely good quality in terms of ripple and reliability.

[@kattan2006]

The best to use is Traco TSR 2-2450. Direct replacement on the PCB, no more heatsink

[@psykix]

Where did that rubber block come from? I have one bouncing around inside also.

[@JanBeta]

There's a spot on the top part of the case that is slightly recessed and fits the rubber block. That's where it goes. If I remember correctly, it holds the heat sink and the tape mechanism in place (I mentioned it in my full restoration video I did some time after this repair video).

[@dh2032]

14:05 I though all spectrum had something wrong with there ram chips, wasn't that a thing, where they got a good deal buying half broken ram chips, and only using the working half of the broken chips in the spectrums?

[@JanBeta]

They did that in the 48k models afaik. They used larger capacity RAM chips they could get for very cheap where half of the chip was faulty and they wired them to use the intact half. Pretty clever thinking. :)

[@AngelValdes2006b]

Hi Jan, Could you show or at least explain how to download and burn the eeprom with the diagnostic file, I actually have the same +2 Spectrum and having a very similar issue. I order from amazon the eeprom burner you used and the chips, but this would be my first time using it... I would appreciate it! :) THanks!

[@JanBeta]

Find the .bin file on the GitHub I linked, if not the correct size copy that file multiple times into a new merged file that has the size of the EEPROM you use (you can use the copy /b command in Windows Terminal), select the correct EEPROM model in your programmer software, burn as binary, insert into the Speccy instead of the original ROM (or use one of the cartridges listed on the GitHub. :)

[@AngelValdes2006b]

@@JanBeta what do u mean by “the correct size”? I order exactly the same eeprom chip u used (27C512), the bin file (testrom.bin) is only 16KB... so it is not 512KB... you want me to somehow merge that bin into itself multiple times until it is 512KB?

[@akkudakkupl]

There are +5V switching regulators available in TO220 footprint ;-)

[@TheSudsy]

Are there any 16k Spectrum videos around - always 48k

[@imachynn]

The only logical enter key layout

[@dolphhandcreme]

How can a linear regulator run cooler as another model? They all dissipate the product of the voltage drop and current running trough, so their temperature on a given heatsink should be identical. Only switching mode regulators should run cooler.

[@JanBeta]

The heat emitted should be determined by the efficiency of the regulator afaik and not only by the voltage drop and current. That's mostly why switching regulators stay so cool. My impression is that the 78S05 linear regulators stay cooler than the 1A rated ones in general but it might just be the difference between the older models and the newly manufactured ones.

[@dolphhandcreme]

@@JanBeta yes, but the efficiency of a linear regulator is a direct function of the voltage drop and current. It's like a regular resistor which has an efficiency of nearly 100% as a heating element. You can think of it like a resistor divider, only that both resistors are variable and controlled by load / regulator. "Kirchhoffsche Regeln" ;-)

[@benbaselet2026]

@@JanBeta All linear regulators just act as resistors so there is no difference in efficiency. A physically bigger part might give better thermal transfer to a good heatsink and run internally cooler that way but the energy lost should be the same.

[@jaycee1980]

@@dolphhandcreme Quiescent current is lower on the newer ones

[@dolphhandcreme]

@@jaycee1980 Is it that relevant? I only found newer datasheets where values of around 5-10mA are mentioned. That's less than 100mW in typical situations. Would be quite interesting to measure some older regulators!

[@bigal115]

Hey Jan, I seem to have the same issue but I don’t have access to rom burning tools. Do you have any suggestions?

[@JanBeta]

There are a couple of RAM test routines that you can start from tape (if you even get the system to start up enough to load something). You can also buy pre-programmed diagnostic ROMs from retroleum.co.uk. And there’s a couple of tricks you can try to figure out faults, listed here: www.spectrumforeveryone.com/features/quickly-diagnose-48k-ram-failures-ninja-style/

[@0toleranz]

Ohh nice - chip puller on Amazon us , $39 plus $360 delivered to Germany - is Jeff Besos hand delivering this personally- or does it come with a complete collection of nowadays rare commodore chips for all of the 8 bit machines 🤪

[@JanBeta]

They are only readily available in the US unfortunately afaik. A friend of mine ordered a couple for a number of people a while back to save shipping cost. I don't remember where he ordered but it wasn't Amazon. :/

[@martinausdeutschland]

Hi Jan. Can these old RAM chips still be bought?

[@JanBeta]

You can often find new old stock ones on eBay and the like still. They are no longer produced unfortunately. But there should still be plenty around that are good.

[@FernandoelChachi]

Now you have to try and show some modern 128K Spectrum games ;)

[@JanBeta]

I will, once I have completely refurbished this machine. :)

[@dimasfajarnugroho5628]

Rural or suburban area or mountain area Will use or need or buy this product all around the world as a kids Toys or other things

[@Edman_79]

The chip name of today is: "I see dirty too". This is what I get for not watching, but only listening :D I had to rewind. Now I know it's IC32. Edit: Fun begins at 11:20 :D

[@JanBeta]

Haha, yeah, I was mumbling a bit there... :D

[@kwanchan6745]

it seems that the first thing people need to do when repairing an 8bit computer is to use the finger test to check whether any RAM chips are insanely hot then use a hot air desoldering tool and whip out all the RAM chips, replacing them with sockets and then using known good RAM in their place once you have a known working position try each of the original RAM chips in turn to see which one(s) are faulty

[@PMCRetroGamer]

Hope the accident 2 days ago wasnt to bad! 🙊🙊 42 days of no accidents is good

[@Hounddoggy33]

20:27 You were close with "ail". It's actually called an "awl".

[@JanBeta]

Yes! I didn't remember the word correctly, got pointed out to me when I first mentioned my "pointy bit" in a previous video. :D

[@JamesPotts]

In English, the "pokey bit" is an awl. Pronounced "all." Some dialects (British?) put a slight break in the "a", giving more of an "ah-uhl". So like "ale" but with a long "a".

[@spacedock873]

Got one of the chip pullers after your recommendation in a previous video. Was very disappointed - it appears to be metal (and should be for the price) but turns out to be cheap silvered plastic as found in model kits. It's okay and quite useful but definitely not worth the price.

[@ojbeez5260]

Best chip pullers are those with a 'corkscrew' mechanism in the middle. Looks a bit like a compass. Let's you gently/incrementally put more and more pressure on the lift. Never accidently damage pins / scratch mainboard again.

[@JanBeta]

Ah, sorry if you were disappointed. They definitely are overpriced for what they are but work very well for me and spared me a lot of bent pins for sure. :/

[@ojbeez5260]

@@JanBeta Best ones are ones that look like a compass. It works kind of like those corkscrew wine bottle openers with two arms. It allows you to clamp the chip in the middle and gently increase leverage on the chip by turning the screw in the middle. Middle arm clamps down while the two outer levers push upwards.

[@xantam23]

Is That a 1000€ Scope on your bench?

[@HuntersMoon78]

Is that a bigger TV?

[@JanBeta]

Yes, a TV I got for free from a friend a while back and fixed. Finally found a use for it after I rearranged my lab a bit.

[@eddiehimself]

It's me again. The word awl is pronounced the same as "all." Probably should have mentioned that originally lol.

[@brianfix4404]

What? No "Hello world" program? Or no "Farts" program? Lol

[@JanBeta]

That would be soooo mainstream! :D

[@fabianfarina2208]

Jan Beta Digital Department Ups! I keep mistaken channels.

[@JanBeta]

Jan Beta's Digital 3rd Floor Spare Room Lab? ;)

[@megan_alnico]

I think the name of that tool is pronounced "all" in the US. Or that could just be a New England thing.

[@lumsdot]

In UK its a bradawl

[@AndrewHelgeCox]

Do Sinclair fans like these ones made by Amstrad after they took over the brand?

[@JanBeta]

I think they are not very highly regarded in the inner circle of Speccy fans actually. The Toastrack has a better standing for sure. :)

[@EmmittBrownBTTF1]

I would have thought a switch mode regulator would be the better regulator, they run cold.

[@tomf3150]

A zx spectrum but an amstrad board ?

[@JanBeta]

Yes, Sinclair got bought by Amstrad and the later Speccy models were made by Amstrad. As far as I know, this is the last model actually designed by Sinclair (and there seem to be some early units that were produced by Sinclair, too).

[@jaycee1980]

@@JanBeta This design is based on the Spectrum 128 Toastrack. The circuitry is almost identical, the only big difference is that Amstrad added a custom logic IC (40057) which implements joystick ports, and the PCB layout is different. The ULA is interchangeable, the only difference again is that the ULA is branded Amstrad, but it is the same as the Ferranti 7K010E5. In fact some Toastracks have the Amstrad part in them

[@MrWaalkman]

I've used these as a 7805 replacement: www.ezsbc.com/product/psu5-2/ Higher output and no need for a heatsink. :)

[@JanBeta]

I'm actually considering using a DC-DC replacement like that but I've had very mixed results with the cheap ones. They often have a lot of ripple and switching noise which sometimes messes up the video signals and such. That's why I often use higher current 7805s as replacements to be sure the machine keeps working as intended.

[@MrWaalkman]

​@@JanBeta I've used one on my Aquarius and didn't see a problem (with an Aquarius it might just go unnoticed :) ).

[@simontay4851]

You could even replace the voltage regulator with an LM338. The LM338 can output 5A and is adjustable so you set the output voltage precisely. www.eleccircuit.com/adjustable-power-supply-1-2-30v-5a-using-lm338/

[@JanBeta]

Yes, that would work. The new regulator I put in runs quite cool though and the 5V supply is very clean so I’m satisfied for now.

[@CezarySiw]

4:40 - Why would a different linear vreg run cooler? If you need to drop from the same to the same voltage with the same current flowing through the circuit, it should dissipate the same amount of heat. If you say that, it would be even worse for the IC to run cooler. It would mean that internal thermals of IC is not as good as in the old one.

[@JanBeta]

I think they are slightly more efficient, that's why they run cooler. Might just be age of the components or new manufacturing processes but in my experience there definitely is a difference in heat dissipation.

[@CezarySiw]

@@JanBeta The only way to run more efficiently is to have a switch mode converter (buck). Every linear regulator basically behaves like a resistor under specific conditions. As you know every resistor has exactly the same efficiency - it turns all lost power to heat.

[@helmia4136]

Nice Video 👍I have a damaged 128 +2 located in Germany/Cologne. Are you interested in repairing it? 😉

[@KolliRail]

Now try playing Tourmaline instead of the old Boulder Dash. Or for something totally different try playing GLUF.

[@JanBeta]

I will once I have this fully refurbished and back in one piece! :D

[@UnreasonableSteve]

Your pokey bit is also known as an awl - pronounced like the word "all"

[@JanBeta]

Ah, that's the correct word! Thanks! I was probably thinking of beer when I called it "ale"/"ail"/whatever... :D

[@blackcountryme]

An awl, a.passer or a gimlet.

[@jaycee1980]

I still have mine... well... i have the PCB and keyboard :)

[@ojbeez5260]

thingiverse - thing no. 2923184 ;)

[@jaycee1980]

@@ojbeez5260 haha, nice... thats for a +2A so wouldnt fit a grey +2 well. I do actually have a case now, which is slightly damaged, so i COULD rebuild it... i usually use it for testing though

[@keeler1701]

Ahh my 2nd computer I owned

[@JanBeta]

It's a nice machine for sure!

[@rdvrdv8920]

Hi Jan Beta

[@JanBeta]

Hi!

[@fkthewhat]

POKIE BIT. GOTTA.. POKE EM ALLL

[@JanBeta]

I'm an expert pokiebit trainer!

[@kaunomedis7926]

Changing 7805 from 1A to 2A will not make it cooler. You can not f...k physics. Heat P = voltage drop × computer current. Replace with DC/DC module to reduce heat.

[@JanBeta]

You are correct, of course. I think the newer voltage regulators might be more efficient? I observed them running a bit cooler a number of times now. No idea why really now that you point out the physics.

[@NotGonnaSayFO]

I am dropping you. Not because of you, but because I will not support KZbin and its fascist policies. Thank you for your content I have enjoyed....