Thanks for taking the time to go through the video signal explanation rather than just solder a capacitor and call it a day! Really informative video!!

This is slowly but surely becoming one of my absolute favorite KZfaq-channels. Really good stuff, well made videos, and interesting topics. :D Thanks!

I got my ZX Spectrum later in January of this year, the composite MOD was something I was more concerned about trying do given my lack of experience in soldering. After watching this video, it helped me out on how to solder a capacitor in the RF lead. I failed to solder it in the first time because I put the capacitor backwards but I managed to solder it in correctly the second time! If I ever introduced someone to the ZX Spectrum and that they have to do the composite MOD to it, I would recommend this video! Thanks for showing us how this composite MOD is done, very helpful video! :)

Excellent video and I really enjoyed the analysis of the signal and explaining what was going on behind the scenes.

Finally someone that has proper tools. Nice presentation thanks for sharing.

This was very useful! Thanks for making awesome videos!

Many thanks, with your video, my old Spectrum start again ;)

Having a luma (Y) and chroma (C) signals available on the board I guess that there is a possibility of adding an s-video jack for even greater video quality output.

I learned a lot about how colour video is generated, thanks!

Another great teaching video, thanks!

You make digital electronics easy, I wish I had teachers like you Haces facil la electronica ojala hubiese tenido profes que explicaran como tu lo hacea

Rewatching this video as I really need to composite mod my Speccy +2A - super helpful video as always - YUV still makes my brain hurt :)

Thank you for explaining everything in such clear and detailed way!!! This is by far the best ZX Spectrum video I have watched so far. 18:23 Where can we get a t-shirt like that?

I remember going from RF to composite, the picture quality improves not only in its sharpness but also in the fact you don't need to tune the TV in.

exellent explanation!!!!!!!! (i would expect a video for black burst , 100% modulation with a vector oscilloscope like we have for servicing camera equipment and beta vcr , dvc pro 50 !!!!!)

Iv done the mod on my old specky that never seemed to tune in correctly. As soon as I first plugged it in I was amazed at the jump in quality

I did'nt put a cap on my comp conv. I'll do them tomorrow. Thanks for the tip. Loving your channel BTW. Subbed after watching 1st vid.

The expansion port (lower pin 15) also has the composite signal, the same one that goes to the rf modulator, so you can get composite signal without modding anything. I don't know why people aren't using this, instead of changing original hardware.

When you held up the back of the ZX spectrum to the light, for example 16:52 , it looks like the case is actually scored for another jack to be installed.

That’s nuts dood!

Just re-watched this to do the mod to my Spectrum 48K+. I can confirm that it works perfectly. The only difference I made was to put the capacitor inside the RF box, just for that more factory look :)

I'm not that interested in "The Speccy" but there's lots of useful info in here for poking into lots of old analogue video devices... thanks.

My ZX Spectrum clones had video output as RGB and Sync out (4 different pins plus GND), so this could be connected to a TV via RGB input like SCART, if I had one back then. What I actually had was a vacuum lamp (tube? what I mean is not a CRT but what was instead of transistors there inside) based monochrome TV and I had to make a "brightness and sync" out of that 4 outputs. So I used one diode for sync and 3 different resistors for mixing RGB signals in special proportions into one signal that TV accepted as brightness with sync (Y-channel actually).

Thanks dude.

Hey. Loving this channel. I hope I can do something similar quality wise. Just a question about the mod; how do you then get the sound to the TV? that was sent over the RF before was it not? I did have the video on whilst I was doing other things, so I may have missed it if you covered it already.

There's a lot of prejudice against the RF connection, but it can have the same quality as the composite-video. All you have to do is to use the correct 50 Ohms cable for the connection. The reason why RF usually looks horrible is because people use composite-video cables with it.

Noel, what scope are you using? Keep up the good work!

Hello, very nice video. I did this with my zx spectrum because i wanted to improve my video. RF was working. I used a 100μf capacitor 16volt because that was available. Strange thing is that i see a very nice picture but after a few minuts (sometimes seconds) he starts to disturb and eventually the image is completely gone. I also tried it without a capacitor. Same problem. Could it have to do with PAL? any idea?

Surprisingly ... Composite looks better on my eyes than RGB, firstly the lines are sharper in the character, and the colours are brigth. Also I could tell the colour of the text down screen.... white/gray (on Composite) vs Yellow (on RGB).

I'm a newcomer to ZX Spectrum and this video was very helpful for me. Many thanks. I will give something like this a try with my Sinclair ZX Spectrum+ 128K when I get tired of RF video. IMO this mod would be even better if there was a way of switching between RF video and composite video (or VGA), perhaps by using an external downconverter/receiver... Also, maybe there is a better mod for Sinclair 128K with its RGB output (I really don't want to use SCART cables though...)?

Loving the channel Noel. I did this mod to mine a while ago but your video made me realise I needed to make a sticker to remind me it's now composite. Hooking up to a real TV isn't practical for me, any chance you could do a video about how to hook our retro machines up to modern monitors? Info I've found online makes it sound very hit and miss if the boxes you can buy will actually work with my 48K, 2600 or Amiga.

Brilliant

I seemed to remember doing the mod on mine back in the 80's however I'm pretty sure I didn't use a cap. Now my monitor was a green screen so not sure what impact that had on color but it did work fine. What is the cap doing?

Do you get color flickering (red purple) on composite modded Spectrum, connected to CRT?

Is polarity of the capacitor important? Is the reason negative terminal connected to the video jack that in case there is direct current flow into the jack the capacitor won't blow up?

Noel; I came with one question... Have you tried the different mods for composite video? with/without transistor? Does it make a chance that could be worthier than without to implement? Thanks

Noel I have a TV with Y/Pb/Pr input,so if i drive the signals from 15th ,16th and 17th ULA's legs to that port it gona give me a working screen?

I recently built a Spectrum 48k from a kit. All works okay with composite mod, but on one TV it doesn’t display colour (monochrome only) and the picture is slightly shifted down the screen. Other TV is fine. I’ve been comparing two signals to see what difference may exist. There is some variability in DC offset. Could this account for behaviour with the two TVs?

Where can I get the program? Thks

Where do I get that TShirt man ?

I find your explanation for the 64 microseconds of the Y, U & V signals awkward and confusing. You are right its the PAL video standard signal with 625 lines at 50Hz that is interlaced which is being used. So every second there should be 50 x 625 = 31,250 lines drawn on the screen (1/31,250 = 32 microseconds), but since it is INTERLACED, there are only half the number of lines that are drawn on the screen per frame, that is 15,625 lines which yields to 64 microseconds (1/15,625 = 64). Interlace is a technique that is used to draw only half the number lines for every frame due to electronic constraints that did not allow TV sets to do full scanning per frame or what is known as progressive scan nowadays. These lines are drawn/displayed in the following order, one frame does the ODD numbered scan lines and the other frame does the EVEN numbered scan lines. The peaks that are displayed in the oscilloscope at every 64 microseconds are for the retrace of the scan line. Also the Y, U & V signals are present on the edge connector as well the composite signal at pin 15 underside.

I'm totally useless at modding but I managed to do the composite mod on my 6 Spectrums

where's the link to the basic program?

I know this is old but what did you do about the sound through the TV?

Do you know how to upgrade the memory of a zx81 from 1k to 64k ?

Would this mod work for the 128k +2a?

That the brighter colour has lower voltage seems counter intuitive. What have I missed?

would 100mf 16v cap work?

Is it possible to remove the entire RF from the 'box'? I ask because I tried it and somehow I have a very terrible signal now. Very unstable. I also removed a piece of the metal casing so I can place a reset switch at that place coming out on the back. But I'm confused why suddenly the picture is so unstable and terrible. Checked for shorts etc but all seems fine. I thought the inner component weren't used anymore.

Can we do this trick with the 48K model (non rubber keys)?

Is there a way to rgb mod it?

Capacitor type ?

nice video but what about sound?

and a lot of ztx tranzistors why they dont use a bc547 or similar

RGB Mod?

Can't we use the YUV and make a component output? Composite still sucks. Also you could compare the composite and RGB on and LCD monitor not a CRT.

Hey Noel. I'm having troubles connecting a zx81 to an old and modern TV. Can you help me? Thanks in advance.

😂😂 cheapest and laziest composite soultion.

Hi Noel,, thanks for another excellent video! An obvious question: would picking up YUV signals work in making a real (albeit YUV) component port?? That would make things soooooo much easier...