My Spectrum Plus

[1024MAK]

Some modern TVs are not very tolerant of the drifting of the frequency of the UHF oscillator in the ASTEC modulators (like used in ZX Spectrums and various other 1980s 8 bit home computers). The UHF oscillator frequency determines the channel frequency (36).

The ZX81s and ZX Spectrums do appear to suffer with this more, as the temperature in the case changes a lot as they warm up from cold. So as they warm up, the frequency of the UHF output changes, but a lot of the modern TVs don’t appear to be able to stay locked to the slowly changing frequency drift. So the quality of the picture degraded until the image from the computer disappears

My workaround is to tune in about 15 channels to channel 36, and fine tune to get a picture. As it degrades I tune in another channel and save it. Then next time, I just channel hop to the next channel

Of course a better solution is to use a SCART lead if a 128 model (although there are problems with this an some modern TVs) or use composite video (if a 16K / 48K / + also modified to output a composite video signal).

Older CRT TVs were definitely more tolerant. They used analogue circuitry and most (except very cheap sets) were designed to cope with slowly drifting frequencies. As their internal oscillator would also drift as well.

Mark

[Juan F. Ramirez]

The next step is getting a Divide interface. Do you think I'll have any compatibility problem (as you can see in the pics it's a issue 6A and an eprom)?

I've found this model to buy:

http://divide.cz/index.php?y=divide.en

I don't understand next thing it says:

'IDE device is needed, this can be HDD, CD ROM, CF IDE adaptor or SD IDE adaptor with memory card.'

Can I use a simple mini SD card?

I need your help, please!

[1024MAK]

The DivIDE uses a parallel bus to communicate to a IDE device. Hard disks drives for PCs used to be parallel IDE (now known as legacy PATA). IDE means integrated drive electronics and PATA means Parallel Advanced Technology Attachment. Both terms are referring to conventional hard disk drives (HDD) as fitted in older PCs.

After starting off with special interfacing, CD-ROM manufacturers switched to producing CD-ROM drives that also connected to a IDE / PATA bus.

Some Compact flash (CF) cards can also be connected to a IDE / PATA bus (but not all will work properly). Compact flash cards are also using a parallel bus. Hence they have lots and lots of pins on their connectors. But there connectors are NOT IDE / PATA connectors. So hence an adaptor is needed.

So you can use a IDE/PATA hard disk drive, or a PATA CD-ROM drive, or a CF in an adaptor with a DivIDE.

Parallel IDE / PATA drives and compact flash cards are / have become obsolete and are expensive and difficult to find. Note that the current HDD technology uses SATA (serial ATA). Although there are PATA - SATA adaptors, I don’t recommend this route.

There are also SD card adaptors that can enable SD cards to be connected to an IDE / PATA bus. The problem is that there are compatibility problems with these, and they won’t work properly when an 8 bit computer is trying to communicate with an SD Card.

The DivIDE was great in its day (I have some), but now I would strongly recommend you go for a Interface that has a SD card slot as standard. So may be the DivMMC EnJOY! SD card and Joystick interface for any ZX Spectrum or the SMART Card V2 Spectrum Interface or a similar type device. It’s well worth browsing the Sell My Retro site and other sites selling expansions and interfaces (including eBay) to see what’s currently available.

Mark

[Juan F. Ramirez]

Mission accomplished!

Thanks to your suggestions, once I got a new keyboard membrane I decided to order a brand new DivMMc interface (Pro Mini Lite version) some time ago. When it arrived, I plugged it in my Spectrum.



It was a historical moment: after more than 25 years, a game were loaded into my beloved Speccy. I'd never imagined Mojon Twin's Ramiro el Vampiro would be the first! (it came with teaser stuff in the micro SD)



Everything was OK. Then, I copied tons of TAP and Z80 files from my laptop in the SD card and tried on the Spectrum.



So so many years after, the code of Alien 8, Fred and others run through the 'veins' of my Spectrum again, wow!

It was curious that when the divMMc is on, there's no problem with the TV signal (unlike as I told you in above posts). Obviously the quality of the image is not as good as if I test it on another device, like a computer. But it's enough for me.

Many many thanks to the people who helped me in this thread!!!

[R-Tape]

Great post to start the week! #Monday Motivation

So so many years after, the code of Alien 8, Fred and others run through the 'veins' of my Spectrum again, wow!

Hmmm. It looks familiar, but I jussst can't place it.

[Morkin]

Raid Over Zythum I think.

[Juan F. Ramirez]

Great post to start the week! #Monday Motivation

I'm glad you liked it. You don't know the excitement I had that day...

[Juan F. Ramirez]

Well, I'm here again.

After playing a lot of games, everything's ok except for the TV signal (already commented above). After an hour (more or less), the UHF signal dissapear from my modern LCD TV.

I checked internet for an affordable solution so I found this page:

https://retrotechlab.com/how-to-connect ... ete-guide/

where some options are described. I dismiss both the ZX HDMI Interface as it's even more expensive than my own DivMMC interface and the 'Simple Composite Modification' one as I'm afraid with my electronic skills I could wrecked it!!!

So an interesting option could be getting a RF to HDMI Converter.

The problem is one of the suggested gadgets is too expensive (225$) so I have the hope of finding a cheap chinese product to be a decent solution (I don't expect 100% HDMI quality, just something to let me play for a long time in a modern TV).

The problem is I got in a 'jungle' of hundred of electronics gadgets with no much idea of what I'm looking for...

https://es.aliexpress.com/item/32901092624.html

https://www.amazon.es/dp/B01CN58B5K

https://www.amazon.es/dp/B00D18UWRY

... and so on...

Any chance of finding a cheap interface?

[Firefox]

The composite mod really is quite straightforward - here's a very nice video showing how to do it:

[media]https://www.youtube.com/watch?v=IocU4fEHAF4[/media]

Fast-forward to about the 12 minute 30 second mark if you don't want to know the theory and just want to see how it is done.

[Morkin]

The composite mod isn't too difficult.

I know nothing about electronics and hadn't touched a soldering iron before I tried it.

I watched a 5 minute video on YouTube on 'how to solder', popped out to Maplin to buy a soldering kit and then followed the instructions. Took about 15 mins. Don't think I've touched the soldering iron since.

[Edit: oops... Firefox got there first..!]

[Ast A. Moore]

The problem is no so much with performing the mod itself—it is, indeed, trivial—but with modern TVs. They’re pretty finicky when it comes to an RF or composite signal, and the Spectrum is renowned for outputting only a crude approximation thereof. Old analog TVs weren’t too bothered with it; modern digital sets are a whole different ballgame.

But the mod is simple, cheap, and easily reversible, so there’s no harm in trying it.

[1024MAK]

There are numerous versions of a ZX Spectrum composite video modification.
Which one, if any, your TV is happy with is a bit of a lottery

Most of them involve disconnecting the modulator wires from the Spectrum’s PCB and removing the connection from the modulators internal circuitry from the Phono/RCA/Cinch output socket.

I’ll list the most common versions in order of complexity:

1. A piece of wire.
2. An electrolytic capacitor,
3. NPN transistor version.

Note that there are other versions, but the above are by far the most common.

If you do decide to have a go yourself, I strongly recommend that (1) you watch every video you can about learning to solder, (2), ask here for help and advice as soon as you have a question or problem, and (3) practice soldering with some wire (thin solid core copper wire like ethernet or telephone cable is fine) and a piece of cheap matrix board, strip board or even a scrap PCB from some other item. Then if you can’t get the hang of it, no Speccy has been harmed

Mark

[Juan F. Ramirez]

Thanks for the replies, mates. But I'm afraid I won't take that option, too risk.. for me it's like surgering your own pet!

I don't even have a soldering tool. I presume it's easier than I thought (thanks [mention]Morkin[/mention] for your hoping words! ) but I prefer exploring the 'chinese' option for now (if this option exist, obvs).

It's no question of time, I'm happy with what I have now, I just want to improve the gaming experience.

I'll keep you informed if I come across something interesting!

[Morkin]

No worries, good luck..

[1024MAK]

The issue 6A board should also have a video signal available on the edge-connector. Even if you don’t want to solder wires to an edge-connector yourself, someone else could do it for you.

Also a video out connector can be added to many interfaces/expansions. For example, to a joystick interface.

The issue of the frequency of the modulator drifting (and hence the TV losing the picture) may still occur with any converter that takes in an RF signal.

Mark