Getting my ZX Spectrum+ up and running again...

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Getting my ZX Spectrum+ up and running again...

Post by Contact Sam Cruise » Thu Oct 25, 2018 4:57 pm

I'm now living in the US and recently collected my old ZX Spectrum+ from its 25 year storage. I'd like to get it up and running again, assuming it still works. I've been reading here and on other websites about issues regarding power supplies and getting the 48K versions to work on modern TVs. Also, I'm aware that the Spectrum puts out a PAL signal, whereas the US is NTSC.

To start with, I've ordered a new power supply from thefuturewas8bit.com. I've also been trying to figure out what to do regarding video issues. I've read about the need to do the composite mod to bypass the RF modulator and that I could then run a composite signal into my flat screen TV - but I could still have PAL vs. NTSC issues?

I had a look at the connections on the back of my TV (Samsung UN65MU6300) and also at the TV's manual. There's an antenna-in connector at the back (which the ZX Spectrum+ TV cable doesn't fit) - see below:

Image

Also, the TV's specifications seem to indicate it has an analogue NTSC/PAL TV tuner (I wonder if it has manual tuning?):

https://www.displayspecifications.com/e ... ay/6653ace

Does this possibly mean the TV might produce a decent image from the my Spectrum's PAL RF output? I can't try it yet until I get the new power supply, but I wondered if anyone else has gotten a 48K Spectrum to work in the US using a modern TV and without needing to perform any modifications.

What type of adapter would I need to connect the Spectrum's TV cable to the back of my TV based on the ANT IN connector in the above diagram? Is it worth even trying this?

Thanks very much for any help or advice.
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Ast A. Moore
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Re: Getting my ZX Spectrum+ up and running again...

Post by Ast A. Moore » Thu Oct 25, 2018 6:43 pm

The composite mod won’t change the signal encoding; it’ll still be a PAL signal (and not a particularly standard-compliant one, at that). If your TV is a multi-system one, there’s a chance it’ll recognize the composite signal coming from the Spectrum, so you’ll be good.

I doubt your TV will like the RF signal more than the composite video, though, but it won’t hurt to give it a go.
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Re: Getting my ZX Spectrum+ up and running again...

Post by Contact Sam Cruise » Thu Oct 25, 2018 7:17 pm

Thanks - it almost seems too good to be true, but I'll try the RF cable first, and then the composite mod next. For using the original TV cable, do you know what sort of connector/adapter I'd need for the antenna input on the back of my TV (see previous posting picture) as the Spectrum's TV cable doesn't fit it (it needs to be 'female' for the Spectrum cable to plug into it).

Also, how can I get around the PAL issue if my TV doesn't recognise that? Any other 48K Spectrum users in the US who can share their experiences?

Thanks again for your advice.
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Ast A. Moore
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Re: Getting my ZX Spectrum+ up and running again...

Post by Ast A. Moore » Thu Oct 25, 2018 7:44 pm

The antenna connectors are trivial to find. The Spectrum will accept a standard RCA plug, and the TV will need an F type coaxial connector, something along these lines. You don’t need it for testing purposes, as you could just stick the bare signal wire into the hole in the TV’s connector and hold the shield around temporarily.

There are PAL to NTSC converters (of varying quality) around. You could try those. Check out this old LGR video for some pointers:

Finally—and this might be the best option quality-wise—you could import a small 14-inch European CRT TV from the early 2000s or so. They usually have a switch-mode power supply, which could be either used directly in a 120V AC environment, hooked up via a step-up transformer, or modified for US outlets internally. Might be less of a hassle in the long run. This would then be your dedicated, as-close-to-the-original-experience-as-possible setup.
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Every man should plant a tree, build a house, and write a ZX Spectrum game.

Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.

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beanz
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Re: Getting my ZX Spectrum+ up and running again...

Post by beanz » Thu Oct 25, 2018 8:31 pm

The composite mod works fine in the US...I've been here 22yrs and have 5 or 6 composite modded...they all work on every LCD/LED screen I've thrown them at with no problems. I think you'll be hard pressed to find a flat panel TV from the last 10yrs that it wont work with...most of them just autodetect and adjust accordingly.

As for power supply any switched 9V 2A one will do, as always be careful with the polarity...if it's wrong just cut the jack off and reverse it.

That's it, nothing to it.
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Re: Getting my ZX Spectrum+ up and running again...

Post by Contact Sam Cruise » Thu Oct 25, 2018 8:43 pm

Thanks for the replies.

@beanz - you mean the TVs detect the PAL signal and adjust?
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beanz
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Re: Getting my ZX Spectrum+ up and running again...

Post by beanz » Thu Oct 25, 2018 8:46 pm

Well I don't know all the technicalities of it, I just know when I hook mine up to composite input they work just fine...and that's using 3 big screen ones and 3 or 4 small screen ones I have/had.

I'd say 'most' are built to autodectect rather than making different ones for different countries...just a guess though.

The 3 or 4 small ones (19" etc) I have I've picked up in the last 5yrs or so at thrift stores for like $10 each...easier to use when just setting up a raspberry pi or PC than the big screen

I always keep an eye out at thrift stores for nice little screens with HDMI, VGA and composite inputs.
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Re: Getting my ZX Spectrum+ up and running again...

Post by Contact Sam Cruise » Mon Nov 12, 2018 4:04 pm

Thanks for all the advice. I did the composite mod as suggested, and with a new power supply designed for a 48K Spectrum I set everything up with a composite cable from the computer into the back of my Samsung flat screen TV. I got a distorted picture along the border of the screen, as well as some flashing coloured squares. The centre of the screen was also black and flashed on and off (as if the computer was being reset). Sadly, it doesn't work... maybe I can get it fixed?
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beanz
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Re: Getting my ZX Spectrum+ up and running again...

Post by beanz » Mon Nov 12, 2018 4:14 pm

Bad memory chip(s) maybe...someone who knows about that will be along shortly Im sure.
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Re: Getting my ZX Spectrum+ up and running again...

Post by 1024MAK » Mon Nov 12, 2018 11:13 pm

Did you try pressing any keys? If the problem is just the TV picture, but the ROM, RAM, ULA and Z80 CPU are working, pressing the keys (apart from the shift keys) should produce a key click sound from the internal speaker.

Can you take a photo of the image you do get on your TV, then please post a link to it here.

Mark
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