Tony, your smile when you heard the Manic Miner tune for the first time is priceless 😊

That title screen "music" on Manic Miner could easily lead anyone to believe the sound was still faulty ;-) Thanks for the entertainment.

I love the passion You put in those repairs :)

That is awesome, especially for 1982..

Great job, Tony ! Always enjoy watching your videos . Cheers !

Well done! Very cool custom case

Thank you for all the work!

cheers tony, nice video for the friday warm down

Pretty impressive. Thank you for this entertaining video!

Another very interesting video!👍👍

38 minutes of Tony-goodness? I'm in😊

Great video!

Back then i was never into the ZX Spectrum, i started with the Commodore ViC20 and did love all the Commodores i had which where many. Great video Tony hope sometime you do some with a Commodore ViC 20. Keep up the good work my friend.

on ZX Spectrum you ALWAYS replace ALL capacitors, no questions asked, EVER!

Sinclair used dodgy RAM - quote from Salkin (UK) website: "The TMS4532 is a 32k x1 bit Dynamic ram. It is actually a 64K static ram that failed testing, in either the upper or the lower portions and was marked appropriately (-4 if the Higher portion was good, or -3 if the lower portion was good.) As such, it comes in two variants that cannot be mixed, the TMS4532-3 and TMS4532-4 variants, which relate to the state required of AR during the CAS phase."

Great video, Tony! I never worked on a ZX Spectrum too but after seeing this video I’m hyped to try it. I only have to find some machine in need of care. It can be also one of the Brazilian clones from Microdigital, the TKs.

Hi Tony anaother great video!much appreciated Thanks

Pretty interesting, subscribed. My first computer was zx spectrum and I spent a lot time playing elite dangerous - David Braben legendary game and now still playing new version

Ah yes. The good old Speccy. My first computer was a second hand 48k +. Marginally better keyboard than the rubber key version. But not by much. I've still got it by the way :-) Re-capped of course. Also got a ZX-HD and DivMMC. You really ran into quite a few issues on this one. Nicely fixed Tony.

That reminds me about the time when I attached a very high quality surplus typewriter keyboard to a ZX 81 with dozens of diodes. ZX Spectrum was for billionaires. We students could afford ZX 81 back then only. But even the ZX81 solved differential equations numerically in Sinclair Basic.

great video, Tony. it has the same age as me, amazing it works fully now :)

Bravo! 🎉😊

I was too young to be playing with these when they came out, I started with the Spectrum +3, but this video was good, there is a 48k in the house, I'm tempted to see if it works...

Some of that "return to black" treatment would of been great for that plastic. Usually for automotive plastics, but I've seen people use it on consoles they fix.

24:32 Freeze spray and heat gun are your friend in a case like this. 🙂

Besides ESR the problem with shot capacitors is that they grow a resistor in parallel, not just in series, that reads as simultaneously possibly an increase in measured capacity and increased VLoss value, they're basically dumping all the current put into them into heat in relatively short order, including the current used by your meter for capacity measurement. Doubled apparent capacitance is probably an indication that it dumps at least half if not more of the current going into it into heat immediately, and then it loses an additional 6% charge per second when not being actively held up. The ESR per se isn't something these old computers are particularly sensitive to, but the loss or parallel resistance, that's really really bad. Also makes me wonder if just replacing capacitors with fresh ones and preferably high temperature grade low loss type would actually reduce the regulator heatsink temperature by a lot. Because all the unproductive current being sunk by capacitor loss needs to be sourced by the voltage regulator, increasing its heat output. I also wonder what one could do to allow the ULA to remain socketable while giving it a heatsink, exactly how much clearence is there. As a rule of thumb, a copper heatsink needs half the volume envelope of the aluminium heatsink for the same thermal performance, so that's one way to save space, you can get relatively low profile ones; furthermore copper has a high lateral conductivity. Maybe all it takes is a 0.8mm thin sheet of copper and let it overhang over less critical components? Making the area 2-3 times the size can be vaguely equivalent to the difference between a sheet and a finned heatsink for area.

Sinclair products were made down to a price, so they wouldn’t have used the higher quality capacitors anyway, so likely they all needed replacement anyway, it’s not just ESR and capacitance, but also leakage.

Good job. Back in the 80s I wrote a spice node network analyzer for the zx spectrum. Almost all in assembly. Still works great. It supports circuits up to 256 nodes. Let me know if you are interested....

I never had one of those nor seen one live. Nevertheless, great repair and video! That audio debugging program had better sound than that game 😅

My guess is that the reason it's reporting "ER stuck high" without the speaker resistance is that it's usind the speaker as pull-down. Clearly other things pulls it down eventually but without the speaker it stays high far too long and this is what the test notices (IE not pulled up, lack of pull down). It might even have cleaned up the audio test waveform, we see that the falling edge takes a very long time to hit zero, this may well be due to this lack of "speaker working as pull-down resistor".

Wow. My ULA had the exact same fault. The letter doubling IIGGOO etc. with the diagnostic ROM. Still haven't been able to fix the RAM fault on mine. After replacing the RAM the test indicated bad did nothing. Maybe I need to replace some other RAM's too.

Ohh,zx, my firsts computer. I assembled the 48k version myself. There were a lot of glitches, but I wrote my first program on it.

👍👍

It was my first computer, and also the only computer I've developed homebrew games for😂

I had that case, but the one with the spacebar. It was a huge improvement over the dead flesh keyboard. Then I bought a BBC Micro which was a huge improvement over the Spectrum. 😉 Discuss.

👍

as for the video input device, i use a gv-usb2 to input some of my older consoles into my pc for various reasons, composite, l/r audio, and svideo inputs, svideo overrides composite. works with ntsc and pal formats fine from what i could tell, but some software suites have issues with the , versus . numeric separators when using the gv-usb2 with them. as far as i know OBS isn't one of them. not sure if this interests you, or is viable with the rest of your setup, but you never know.

good stuff .. when you showed your other spectrum, it looked to me that the upper ram link was not fitted.. this can cause problems

Just have done with it and socket them all. Then go back and recheck the 'faulty' mem chips. The diagnostic may have misreported as all data/address lines are connected to each other. Other chips 'may' be OK.

I had one that had a similar fault but its many years ago and i didnt get it to work.

More than one fault almost always indicates a meddling pillock who had no idea what he was doing. If he did know, he would have fixed it, if he didn't fix it, he probably didn't know that his inexpert meddling would just make things worse. Think of the detective and some idiot has contaminated the crime scene.

You deal with vintage computers but you dont have a TV ? OMFG

* A technician repairing machines of that era must have a television with a multi-standard RF input. It is something essential. * Please stop bothering everyone with "subscribe" and "hit the bell". If you create good videos, people will. It is impossible to subscribe to all the channels you watch. I wouldn't even have time to watch the videos. * If the computer is executing code, all lines in the data bus are correct. You don't need to check it. * All electrolytic capacitors must be replaced. If they haven't failed yet, they will fail in no time. It's something every technician knows. The computer is running. Congratulation. But you need to understood and learn from your mistakes.