Spectrum Computing

Rummaging through my underground Attic I rediscovered about 300 old Spectrum games, 3 old 48K spectrums and a Spectrum128+. There was original power packs for both models and they have good outputs. I connect the tv output to the coax socket on my digital tv but of course, (stupid me) i surely need the tv to be an analogue device. Or do I?
Haven't used the speccy for years of course but I used to add titles to my videos way back when. Still have the video interface plug ins and programmes to do the effects, and was curious to see if they still work.
The 48K models don't beep when they are powered up but 128K plus model does gently warm up the heatsink after a while, but without the output I can't tell.
Is it worth persuing the resurrection or should I just flog off the software, (some of which seem to have some value)?

[mention]denjerus[/mention] You can buy a SCART cable from Retro Computer Shack for the 128 which will give you a good picture on most modern TVs.

https://rover.ebay.com/rover/0/0/0?mpre ... 0949446667

Thanks PeterJ. I've ordered that after faffing about all day with boxes of connectors that would surely "come in Handy" but didn't.
Then lets hope it will work. Thanks for the quick response. I had looked on ebay but obviously searche for the wrong thing. Thanks Again, I'll let you know if it works.

Well I got the lead, Very quick delivery considering the weather we've had. Unfortunately my TV screen is mostly Black but you can discern the Black border around the black stiped central portion that visuals used to appear in. Looks like time has taken its toll on the innards The heatsink has warmed up and I've left it turned on for a while to dispel any moisture in there, but it looks terminal from here, Any thoughts??

Is it the 128k machine? If so, then the TV expects a composite signal but receives only the vertical sync. If you can manually select RGB on your TV, do so. If not, there are two options. One is to use the composite video output from the Speccy. The other is to feed a suitable voltage to the BLANKING pin on the SCART connector, which is not as straightforward.

It is possible that the digital TV is not compatible with the lead. Some digital TVs don't lock on to the signal or have a jumping/flashing image. My Samsung is fine with the lead, my Matsui is hopeless so it has the composite signal instead and works fine. If you have a few TVs to test with then give each of them a whirl.
The 128 machine can be tested by plugging in a set of headphones into the ear/mic socket, press a few keys (not Enter) and if you hear click via the headphones then the machine is working, just need to get a steady picture output.

It's because the Spectrum 128 isn't compatible with SCART without modifications (or a powered RGB-SCART cable)

Guesser wrote: ↑Wed Mar 21, 2018 1:50 pm It's because the Spectrum 128 isn't compatible with SCART without modifications (or a powered RGB-SCART cable)

Some TVs (mine, for instance), allow you to manually choose between RGB and composite video inputs on the SCART connector. I still wired my cable with composite video on pin 20, rather than vertical sync. It’s fun to switch between RGB and composite and compare picture quality. But mostly to freak people out by playing this (wink-wink, nudge-nudge).

P.S. A button-cell battery inside the SCART connector might also do the trick in the short term, though the easiest way to go is to feed the required 1–3 V to pin 16 from inside the TV itself.

Ast A. Moore wrote: ↑Wed Mar 21, 2018 3:02 pm I still wired my cable with composite video on pin 20, rather than vertical sync.

That is the correct wiring, SCART wants a composite sync or composite video. The 128 only provides separate horizontal and vertical syncs.

Ast A. Moore wrote: ↑Wed Mar 21, 2018 3:02 pm P.S. A button-cell battery inside the SCART connector might also do the trick in the short term, though the easiest way to go is to feed the required 1–3 V to pin 16 from inside the TV itself.

A coin cell won't last long at all driving the blanking pin, on the order of a few hours. I wouldn't say modifying the TV is easiest, better to make a passthrough cable for the 9v supply feeding a suitable resistor. (Not sure why RGB cables for the Spectrum 128 don't come like this already frankly)

Guesser wrote: ↑Wed Mar 21, 2018 3:40 pm The 128 only provides separate horizontal and vertical syncs.

Oh, sorry, I misspoke. I meant composite sync, not vertical sync. But since the composite sync is already present in the full composite signal, I decided to go with the latter. (I originally wired the composite sync signal; then after trying out Chromatrons, I decided to leave go with the full composite signal. Tons of fun!)

Ast A. Moore wrote: ↑Wed Mar 21, 2018 3:02 pm A coin cell won't last long at all driving the blanking pin, on the order of a few hours. I wouldn't say modifying the TV is easiest, better to make a passthrough cable for the 9v supply feeding a suitable resistor. (Not sure why RGB cables for the Spectrum 128 don't come like this already frankly)

Ha! A passthrough power supply cable is an excellent idea. Hadn’t thought of that. For me, though, that’d be more fiddly than the simple TV mod (primarily, because I’d need to source a male 2.1 mm plug + female socket, and cobble together something of a neat enclosure for them).

Ast A. Moore wrote: ↑Wed Mar 21, 2018 4:49 pm (primarily, because I’d need to source a male 2.1 mm plug + female socket, and cobble together something of a neat enclosure for them).

Inline socket, with one cable off to the SCART plug and another a couple of inches long to the plug. No extra enclosure required.

Guesser wrote: ↑Wed Mar 21, 2018 6:19 pm Inline socket, with one cable off to the SCART plug and another a couple of inches long to the plug. No extra enclosure required.

Hmm. Having trouble visualizing it, but I guess you’re right.

Wow. Thanks for the huge response from all you guys.
I made a the mistake of thinking this would be either a simple "its gone belly up, ditch it" or maybe "Check you've got the plug in properly."
it's been best part of 30 years since I took a plug apart and back then there was 3 cables in it, and a 13 amp fuse! Now there's talk of a pin 20.... where do I get a composit lead to put on pin 20?
I must have given the impression I knew what I was talking about.. My bad!
Is there a chance any of you guys could type slowly how I go about powering this RGB to SCART cable (refered to in the initial slots of this feed) or turning the vertical sync to a composite sync.
or should I seek a computer guy in town to sort it for me?

Definitely! There's a huge breadth of knowledge and diagnostic skills about Spectrum matters out there generally, and on this forum. And pretty much everything is repairable.

Sections 5.2 and 5.3 of this document cover making a powered SCART cable for your 128+.

edit: numbered as the paragraphs are, on pages 7 and 8. Ignore the numbering in the Table of Contents.

denjerus wrote: ↑Wed Mar 21, 2018 7:18 pm where do I get a composit lead to put on pin 20?

Well, for starters, Robin gave you a link to a pretty good guide. That should give you a general understanding of which signal goes where.

There’s no guarantee that the composite signal is present in the lead at all. It could have been omitted in the wiring altogether. (As I mentioned earlier, it’s not necessary for the RGB signal, so whoever made the cable you have might have used the CSYNC signal instead.) If that is the case, while technically wasteful, it might prove useful in the long run to simply use the existing conductor in the cable and rewire it on the DIN 8 (Spectrum) end from pin 4 to pin 1. On the SCART end, you’ll want to remove the two resistors that form a voltage divider, and replace them with a single series resistor of, I don’t know, 33–47 Ω.

The TL;DR version: we need to connect pin 1 (instead of pin 4) of the DIN 8 plug to pin 20 of the SCART.

Don’t be overwhelmed by the number of conductors in the SCART connector. You’re only interested in about half a dozen of them.

denjerus wrote: ↑Wed Mar 21, 2018 7:18 pmshould I seek a computer guy in town to sort it for me?

Bah, where’s the fun in that?

You can find details on how to make your 128 Spectrum SCART compliant here (requires a little soldering, well within the reach of a beginner):
https://spectrumforeveryone.com/technic ... compliant/

Ast A. Moore wrote: ↑Wed Mar 21, 2018 4:49 pm

Guesser wrote: ↑Wed Mar 21, 2018 3:40 pm The 128 only provides separate horizontal and vertical syncs.

Oh, sorry, I misspoke. I meant composite sync, not vertical sync. But since the composite sync is already present in the full composite signal, I decided to go with the latter.

It's my fault, I was talking rubbish and confusing the issue again. The 128 has VSYNC and CSYNC, I was muddling it up with monitors with VSYNC and HSYNC.

balford wrote: ↑Wed Mar 21, 2018 10:32 pm You can find details on how to make your 128 Spectrum SCART compliant here (requires a little soldering, well within the reach of a beginner):
https://spectrumforeveryone.com/technic ... compliant/

I feel like that article misses a trick by not also describing the mods to put audio on pin 3 and the second 12V on pin 5. One SCART cable pinout to rule them all (and fully support all the SCART signals)

I suppose they're somewhat more involved on the 128, needing wire to patch signals across.

Guesser wrote: ↑Thu Mar 22, 2018 12:03 am It's my fault, I was talking rubbish and confusing the issue again. The 128 has VSYNC and CSYNC, I was muddling it up with monitors with VSYNC and HSYNC.

No worries, mate. I knew exactly what you meant.

Guesser wrote: ↑Thu Mar 22, 2018 12:08 am I feel like that article misses a trick by not also describing the mods to put audio on pin 3 and the second 12V on pin 5. One SCART cable pinout to rule them all (and fully support all the SCART signals)
I suppose they're somewhat more involved on the 128, needing wire to patch signals across.

When I got the Toast Rack, I was briefly tempted to stuff the brightness mixing circuitry inside the machine and rewire the socket to match a +2A/+3 so I could use the same cable for both machines. (Besides, I didn’t have any more DIN 8 plugs on hand.) It just felt . . . wrong, so I made a separate cable. I did try to match the signal levels between the machines, which took several tries and combinations of resistors in the voltage dividers. The kitchen walls resounded with many a strong word that day.

denjerus wrote: ↑Sat Mar 17, 2018 12:25 pm Rummaging through my underground Attic I rediscovered about 300 old Spectrum games, 3 old 48K spectrums and a Spectrum128+.

ZX Spectrum 16k, ZX Spectrum 48k and ZX Spectrum+ machines all have an internal "loud" speaker (although not that loud, especially with early issue machines ...), but none of these beep when powered up.

So you don't need to connect any display to see if they are working. Power on and press and hold a letter or number key, and if it is working, you should hear the key "click" noise.

Reset (power down/up with the rubber key machines) and blind "type" BEEP 5,5
That is press [EXTEND MODE] (a key on the plus, [CAPS SHIFT] and [SYMBOL SHIFT] on the rubber key), then press and hold [SYMBOL SHIFT] while pressing [Z], then enter [5][,][5][ENTER].
Note on the rubber key, you get a comma [,] by pressing [SYMBOL SHIFT] and [N].
You should then hear a tone from the speaker.

Of course, if the keyboard membrane has failed, part or all of the keyboard won't work, and membrane failure is rather common with machines that have been used a lot.

If you have a TV with a composite video input (normally the physical connector is a phono / RCA / Cinch connector with yellow insulation or a SCART connector) then a ZX Spectrum 16k, ZX Spectrum 48k or ZX Spectrum+ machine can be modified fairly easily to output composite video instead of UHF.

Mark

Oh, and some 'digital' TVs are capable of receiving and displaying the analogue UHF TV signal from the 1980s and 1990s computers.

I have a Sharp AQUOS LCD TV that works okay. You most likely will have to use the manual channel search and the fine tune controls though. Start with TV 'channel' frequency 35, 36 and 37 including in between channels. This is because the modulators used in the Sinclair machines is purely analogue and does not output on an exact TV standard frequency.

Mark

1024MAK wrote: ↑Thu Mar 22, 2018 8:12 pm Oh, and some 'digital' TVs are capable of receiving and displaying the analogue UHF TV signal from the 1980s and 1990s computers.

I don't think I've seen a digital terrestrial tv that doesn't have an analogue tuner yet. Maybe some so-called "smart" ones?

Guesser wrote: ↑Thu Mar 22, 2018 12:08 am I feel like that article misses a trick by not also describing the mods to put audio on pin 3 and the second 12V on pin 5. One SCART cable pinout to rule them all (and fully support all the SCART signals)

I suppose they're somewhat more involved on the 128, needing wire to patch signals across.

Indeed, kinda wanted to steer away from anything too complex in that one, it’s a ‘get you going’ article first and foremost.

There are plenty of other corners of the interweb that can go into that level of excruciating detail

balford wrote: ↑Fri Mar 23, 2018 12:57 am Indeed, kinda wanted to steer away from anything too complex in that one, it’s a ‘get you going’ article first and foremost.

Indeed, "patch wires across the board" is a bit "scare people away". On the other hand switching the +2 over to SCART is just more of the same with links

Maybe I should write my own page about SCART cables and mods... with blackjack! and hookers! In fact, screw the SCART cable thing.