ZX81 monitor
Re: ZX81 monitor
Double check everything if it makes sense with your computer system. i.e. no USB then no USB peripherals. If you have a HDMI input on your laptop, you could use a video demodulator/convertor to convert RF NTSC to HDMI. (MOST DO NOT)
In any event your are still buying something... Let me know how it works out.
I reserve the right to be wrong and to commit the wrong of being right (correct)!
In any event your are still buying something... Let me know how it works out.
I reserve the right to be wrong and to commit the wrong of being right (correct)!
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
Re: ZX81 monitor
Hi again:
I've tested the hardware, and it works, but the image quality is really bad.
Maybe it is a matter of fine tuning?
Actually the background color is dark grey instead of white.
I've tried channel 2 and at freq 55.25 MHz
Any ideas?
I've tested the hardware, and it works, but the image quality is really bad.
Maybe it is a matter of fine tuning?
Actually the background color is dark grey instead of white.
I've tried channel 2 and at freq 55.25 MHz
Any ideas?
Re: ZX81 monitor
Actually, the image could be much better, it's strange, because sometimes it flashes and for a fraction of a second the image is perfect (white background and very clear characters).
I will try to post images/videos. I think with a small tuning, this device could work perfectly.
I will try to post images/videos. I think with a small tuning, this device could work perfectly.
Re: ZX81 monitor
Playing with hue/saturation I was able to get a much better picture.
There is still a colorful flickering around the black color of the fonts which I am not able to get rid of.
Attached is a video.
Please tell me your opinions.
There is still a colorful flickering around the black color of the fonts which I am not able to get rid of.
Attached is a video.
Please tell me your opinions.
- Attachments
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- 20160914-130043.mpg
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- RetroTechie
- Posts: 379
- Joined: Tue Nov 01, 2011 12:16 am
- Location: Hengelo, NL
- Contact:
Re: ZX81 monitor
Ahh, the joys of RF modulation and an ULA walking on its last legs... (like almost every Zeddy out there)
Want better? Start with a composite mod! Yeah I can understand if someone doesn't want to touch a ZX81 inside (and -somewhat- agree due to fragile keyboard connectors etc). But hey, that's the basic choice you have: do a bit of internal modding, or live with VHF/UHF crap output.
Want better? Start with a composite mod! Yeah I can understand if someone doesn't want to touch a ZX81 inside (and -somewhat- agree due to fragile keyboard connectors etc). But hey, that's the basic choice you have: do a bit of internal modding, or live with VHF/UHF crap output.
Re: ZX81 monitor
The question is the following:
That's the better quality you can get from a VHF/UHF output or I can get better if I play with the capturing hardware or wired or whatever else?
thanks.
That's the better quality you can get from a VHF/UHF output or I can get better if I play with the capturing hardware or wired or whatever else?
thanks.
- 1024MAK
- Posts: 5153
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: ZX81 monitor
I'm not sure what you are asking...
But, any UHF or VHF picture will be poor, due to the large number of compromises needed to get a TV picture to fit into what originally was a monochrome picture channel (and there are plenty of compromises for the monochrome picture already...).
The reason you get blurred colour effects, is due to the colour decoder being confused by the video signal translations between "black" and "white" or vice-versa.
If there is an option to turn off the colour decoder, this will improve matters.
But as RetroTechie says, your best option is to convert the Zeddy to output composite video
Mark
But, any UHF or VHF picture will be poor, due to the large number of compromises needed to get a TV picture to fit into what originally was a monochrome picture channel (and there are plenty of compromises for the monochrome picture already...).
The reason you get blurred colour effects, is due to the colour decoder being confused by the video signal translations between "black" and "white" or vice-versa.
If there is an option to turn off the colour decoder, this will improve matters.
But as RetroTechie says, your best option is to convert the Zeddy to output composite video
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Re: ZX81 monitor
@1024MAK
What I meant is:
I think that the picture I am getting by using this USB adaptor is worst than the picture you get if you plug in the Zeddy to an analog TV set. Or is it the same?
What I meant is:
I think that the picture I am getting by using this USB adaptor is worst than the picture you get if you plug in the Zeddy to an analog TV set. Or is it the same?
- 1024MAK
- Posts: 5153
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: ZX81 monitor
I think that vey much depends on the TV. And which version of the ULA chip is fitted to the ZX81 / TS1000.
I have a LCD TV that produces a reasonably good picture via UHF, even with the ULA chip that does not include the part of the video waveform known as the "back porch". Only the last produced ULA has this "back porch" part of the signal.
Older CRT type TVs are/were more tolerant of the non-standard video outputs of retro computers. Some of the more modern colour CRT sets were not happy, with the user having a picture with poor contrast. Some LCD TVs also dislike the video output from Zeddy computers.
And then there is the tuning drift caused by the computer heating up... Some TVs can track the signal, others can't.
Converters typically are more tolerant, as they are normally multi-standard. While some modern TVs may only work with one or two video standards.
Mark
I have a LCD TV that produces a reasonably good picture via UHF, even with the ULA chip that does not include the part of the video waveform known as the "back porch". Only the last produced ULA has this "back porch" part of the signal.
Older CRT type TVs are/were more tolerant of the non-standard video outputs of retro computers. Some of the more modern colour CRT sets were not happy, with the user having a picture with poor contrast. Some LCD TVs also dislike the video output from Zeddy computers.
And then there is the tuning drift caused by the computer heating up... Some TVs can track the signal, others can't.
Converters typically are more tolerant, as they are normally multi-standard. While some modern TVs may only work with one or two video standards.
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Re: ZX81 monitor
I am thinking in trying the component mod.
Where I can find an easy one and with a step by step instruction??
It is absolutely mandatory to have solder skills? (then I need to practice first and get a solder and all the corresponding stuff).
thanks.
Where I can find an easy one and with a step by step instruction??
It is absolutely mandatory to have solder skills? (then I need to practice first and get a solder and all the corresponding stuff).
thanks.