2 red lines on the screen
2 red lines on the screen
Hi,
New to this forum and wondering if someone has an idea related to my problem.
Just started up once my old Spectrum 48K.
I’m using the mod for the composite signal.
Computer seems to work fine but there’s clearly noise on the screen. More specific 2 horizontal red coloured lines that split the screen in 3 parts.
Any idea where these lines come from or better I post also a screenshot?
Regards
New to this forum and wondering if someone has an idea related to my problem.
Just started up once my old Spectrum 48K.
I’m using the mod for the composite signal.
Computer seems to work fine but there’s clearly noise on the screen. More specific 2 horizontal red coloured lines that split the screen in 3 parts.
Any idea where these lines come from or better I post also a screenshot?
Regards
- 1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: 2 red lines on the screen
Hello and welcome
You may wish to say hello and introduce yourself in the welcome area
Yes a photo would definitely help, as I’ve not heard of this problem before...
Mark
You may wish to say hello and introduce yourself in the welcome area
Yes a photo would definitely help, as I’ve not heard of this problem before...
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: 2 red lines on the screen
Hi all,
In attachment 2 screenshots. Not so easy to take a good picture.
Not sure if this is normal but screen also look very blue. I expected white (or close to that)
In attachment 2 screenshots. Not so easy to take a good picture.
Not sure if this is normal but screen also look very blue. I expected white (or close to that)
Re: 2 red lines on the screen
looks very mysterious - is it possible to try it with an other monitor or tv? The red lines are looking so perfect - much clearer than the "NEW" prompt
Re: 2 red lines on the screen
They also exceed the width of the Spectrum's display area too almost as if it was an artifact of the TV rather than a fault with the computer.
Does changing the paper colour make any difference?
Does changing the paper colour make any difference?
Re: 2 red lines on the screen
Thanks,
Good idea to see the impact of changing paper color.
Will also try on another screen and see the outcome
Good idea to see the impact of changing paper color.
Will also try on another screen and see the outcome
-
- Posts: 2173
- Joined: Sat Nov 26, 2016 2:42 am
Re: 2 red lines on the screen
Is it an issue two PCB? They have adjusters for the colour mix (I have issue two which has a blueish screen) but are not that easy to work with. Apparently an oscilloscope is recommended.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
- 1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: 2 red lines on the screen
As do issue one boards, but the preset resistors (variable resistors) only change the overall colour encoding. So they affect the white / yellow / blue (etc) colours of the whole screen. But I can’t see how poor adjustment can cause those horizontal red lines.Lardo Boffin wrote: ↑Sun Jan 03, 2021 6:32 pm Is it an issue two PCB? They have adjusters for the colour mix (I have issue two which has a blueish screen) but are not that easy to work with. Apparently an oscilloscope is recommended.
Although a ‘scope is recommended in the service manual, it’s often easier to set them by eye if you program the machine to show a screen with all the colours.
Later issue boards (three onwards) have different colour bias circuitry and don’t need manual setting up.
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: 2 red lines on the screen
Hi guys,
Yep,
Root cause was the TV. Another one provides a nice screen.
Found out 2 columns of keys not working. Will need to check flatcables...
Yep,
Root cause was the TV. Another one provides a nice screen.
Found out 2 columns of keys not working. Will need to check flatcables...
Re: 2 red lines on the screen
Compositie signal from my WII works fine on the first TV. Weird it has problems with the Spectrum.
Perhaps better install a composite module than the current wire bridge....
Perhaps better install a composite module than the current wire bridge....