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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 20th Aug 2021, 6:51 pm   #1
ScottishColin
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Default ZX Spectrum Issue 2 / new TVs

Good evening all - I hope a post about the Spectrum isn't out of place here.

I've just bought a working Spectrum Issue 2 and can't get it to tune in on the TVs in the house - I'm guessing that's due to an analog/digital issue.

My preference would be (as with the PET you all helped me fix) to leave the Spectrum with as many original parts in it as possible - has anyone got a Spectrum communicating with a shiny new flat-screen TV and if so, can someone help me with the changes I might need to make?

Thanks.

Colin.
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Old 20th Aug 2021, 7:04 pm   #2
Dave Moll
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Default Re: ZX Spectrum Issue 2 / new TVs

If the television is digital-only (no access to analogue channels) it will be unable to find the output from the Spectrum. You will need a television with an analogue tuner (or something that will accept this signal and convert it into an acceptable input to the television).
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Old 20th Aug 2021, 7:42 pm   #3
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Default Re: ZX Spectrum Issue 2 / new TVs

In all honesty it is probably better to make the composite mod that just direct connects the video out through to the Tuner RCA socket - it can be done carefully so is easily reversible. The Issue 2 is a beast to get the colour right at the best of times but, in my opinion one of the best.

When you say you can't tune it are you sure it is working? It is vital you test the three power rails as if the 12v circuit has failed the Lower RAM chips will be destroyed.
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Old 20th Aug 2021, 7:43 pm   #4
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Default Re: ZX Spectrum Issue 2 / new TVs

https://spectrumforeveryone.com/tech...the-48k-range/ I usually fit the capacitor...
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Old 20th Aug 2021, 7:46 pm   #5
ScottishColin
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Default Re: ZX Spectrum Issue 2 / new TVs

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Originally Posted by Timbucus View Post
In all honesty it is probably better to make the composite mod that just direct connects the video out through to the Tuner RCA socket - it can be done carefully so is easily reversible. The Issue 2 is a beast to get the colour right at the best of times but, in my opinion one of the best.

When you say you can't tune it are you sure it is working? It is vital you test the three power rails as if the 12v circuit has failed the Lower RAM chips will be destroyed.
Hi there. It was sold as working and when I plug it in I can hear the soft clicks when I press they keys so I think that's a good sign.

I'll cstheck your link so I can test my soldering skills once more.

Thanks.

Colin.
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Old 20th Aug 2021, 7:48 pm   #6
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Default Re: ZX Spectrum Issue 2 / new TVs

Link cross posted - it does assume you have a TV with composite in or SCART that has it with a suitable adapter.
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Old 20th Aug 2021, 8:01 pm   #7
ScottishColin
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Default Re: ZX Spectrum Issue 2 / new TVs

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Originally Posted by Timbucus View Post
Link cross posted - it does assume you have a TV with composite in or SCART that has it with a suitable adapter.
I have a scart block that is used for the Wii. No-one will notice that if I borrow it.

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Old 20th Aug 2021, 9:09 pm   #8
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Default Re: ZX Spectrum Issue 2 / new TVs

Evening Colin, nice to have you back. As we recall, you have a scope. Power the Spectrum on and try scoping the wires which rise up from the PCB and pass through the side of the modulator can. One of those should have a video waveform on it.

You need to be sure that video waveform is present before you set about trying to do the composite mod, otherwise you may have a fault somewhere further back.
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Old 23rd Aug 2021, 2:46 pm   #9
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Default Re: ZX Spectrum Issue 2 / new TVs

Colin, did you want to get your spectrum running on a big screen, or just looking for a way to get it working? Bionicmerlin is offering a couple of portable crt tvs that might be worth a go, though not exactly local for you.
https://www.vintage-radio.net/forum/...d.php?t=183090
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Old 23rd Aug 2021, 10:34 pm   #10
ScottishColin
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Default Re: ZX Spectrum Issue 2 / new TVs

Hi Sirius / Mark. Good to hear from you.

I dug out an old video recorder tonight and pushed the Spectrum signal through that and a SCART cable to our flat screen and it works (not the most beautiful picture but I managed to run Hello World).

I guess an old CRT is probably my best bet if it's not easy to change things to run through a flat screen. If anyone's done any Spectrum conversions that I might manage, that would be nice to know though.

Colin.
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Old 23rd Aug 2021, 11:00 pm   #11
SiriusHardware
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Default Re: ZX Spectrum Issue 2 / new TVs

Neat trick, using a VCR as an analogue RF to AV converter.

Well, the good news is that people practically (or in fact, actually) give old CRT TVs away, although they do tend to be the larger ones. Something like a 14" colour Ferguson 37149....

https://www.golden-agetv.co.uk/img/equipment/285b.JPG

...would be a perfect period match for a Spectrum, if you can find one.

To be honest the RF-video output from the original Spectrum was never very pretty. As always, what you can do about that depends on how deep your pockets are. For example, this plug-in multi purpose interface made by the redoubtable Paul Farrow...

http://www.fruitcake.plus.com/Sincla...aInterface.htm

...extracts the screen information directly from the buses, bypassing all of the original video circuitry without modifications to any of it, and outputs it as a clean SCART RGB signal. It's worth looking through the whole site which has a lot of interesting stuff for ZX80 / ZX81 and Spectrum.

http://www.fruitcake.plus.com/

Another way to get a nice picture from a Spectrum is to get one of the later ones (Spectrum 128, 128+2, etc) - unlike the original Spectrum they have RGB-out as standard - I think it's TTL-level RGB, but easily converted to 'linear' RGB levels with a suitably made interface / lead.
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Old 25th Aug 2021, 2:08 pm   #12
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Default Re: ZX Spectrum Issue 2 / new TVs

Of course you could go full HDMI as well... https://www.bytedelight.com/?product...o-complete-set
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Old 25th Aug 2021, 2:50 pm   #13
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Default Re: ZX Spectrum Issue 2 / new TVs

Not a bad idea, most really modern TVs only come with HDMI connections and possibly an afterthought composite / AV connection (not RGB) if you are lucky.

I gather the reason so many of these video-to HDMI projects are based on the R-Pi, apart from the fact that it's just very useful that way, is because the Rpi includes an HDMI licence in with the price?
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Old 25th Aug 2021, 3:09 pm   #14
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Default Re: ZX Spectrum Issue 2 / new TVs

Though if you're willing to make the composite output mod described earlier, a generic composite-to-hdmi converter could be used for a little over a tenth of the price.

Admittedly, the Bytedelight unit should give a superior output quality, as it avoids the quality losses caused by going via composite.
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Old 28th Aug 2021, 5:42 pm   #15
ScottishColin
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Default Re: ZX Spectrum Issue 2 / new TVs

After an appeal on the local Facebook group, I have a beautiful 'portable' Technosonic pink TV.

Turns out they might have some BBC computers in their loft too.....
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Old 28th Aug 2021, 5:44 pm   #16
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Default Re: ZX Spectrum Issue 2 / new TVs

Lovely - is it working fine now? We need pictures...
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Old 28th Aug 2021, 9:02 pm   #17
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Default Re: ZX Spectrum Issue 2 / new TVs

Quote:
Originally Posted by ScottishColin View Post
After an appeal on the local Facebook group, I have a beautiful 'portable' Technosonic pink TV.

Turns out they might have some BBC computers in their loft too.....
One of my old girlfriends had a TV like that with a built in DVD player.
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Old 28th Aug 2021, 9:21 pm   #18
SiriusHardware
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Default Re: ZX Spectrum Issue 2 / new TVs

Quote:
We need pictures...
Of the screen, please... not the pink TV. Given your recently acquired experience with respraying things, maybe you could spray it very, very, dark grey.

Or white.

Basically, anything but pink.

BBC Bs are nice machines with 'proper' microprocessor architecture much like the PET - one thing to watch out for is the RIFA capacitors on the mains input side of the power supply, they have a habit of going up with a spectacular bang if the machine has not been powered up for a decade or two. Usually no serious harm done but it is better to pre-emptively replace them before turning the machine on.
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Old 29th Aug 2021, 2:48 pm   #19
ScottishColin
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Default Re: ZX Spectrum Issue 2 / new TVs

Here you go. It indisputably works, although I wouldn't want to be staring at this screen for hours - a bit flickery for my taste. And the graphics on the front of the game don't quite match the graphics on the screen - occupational hazard for the Spectrum owner as I recall. That's why I used to buy Crash magazine for the reviews.

Oh - and I had to resort to this old fashioned thing called a camera - the banding was just too bad using my phone's camera.

Now to find Manic Miner, Jet Set Willy and Football Manager. Wasted days of my life on them.
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Old 29th Aug 2021, 3:19 pm   #20
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Default Re: ZX Spectrum Issue 2 / new TVs

Looks like a good quality picture - was that with a composite mod? That would improve the picture a lot... clever way to include a photo of that Hello Kitty stickered beast which somehow goes well with the Spectrum - Sirius will have to crop the image!
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