Dear All,
I'm successfully resurrecting my old 48K Spectrum. So far I've done a simple Video Mod, and replaced the keyboard membrane and the voltage regulator. The only slight thing left to do is sort these faint black lines on the screen. Any thoughts as to what might be causing them? And is the chirping noise/whistling noise likely to be the coil? Does that need replacing, or does it not really matter?
With many thanks,
Christopher (Worcester, UK)
Faint thin vertical black lines on screen 48K
Faint thin vertical black lines on screen 48K
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- 1024MAK
- Posts: 5118
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Re: Faint thin vertical black lines on screen 48K
Hello and welcome Christophercjba100 wrote:Dear All,
I'm successfully resurrecting my old 48K Spectrum. So far I've done a simple Video Mod, and replaced the keyboard membrane and the voltage regulator. The only slight thing left to do is sort these faint black lines on the screen. Any thoughts as to what might be causing them? And is the chirping noise/whistling noise likely to be the coil? Does that need replacing, or does it not really matter?
With many thanks,
Christopher (Worcester, UK)
The vertical faint black lines on the screen are not unusual on a Spectrum. In most machines, they can be reduced by replacing some capacitors. Have you renewed the electrolytic capacitors yet?
The whistling noise does indeed come from the "coil". This is actually a pulse transformer and it forms part of a DC to AC to DC converter. The noise is normal. Parts of the coil vibrate, that's what you can hear, as the frequency is in the audio range. The issue 1 and 2 boards were rather loud. The later issue boards had coils that were quieter.
Which issue number is your board?
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
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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: Faint thin vertical black lines on screen 48K
It's a 3B board.
No, I haven't replaced any capacitors yet. That's the next little project I think...
Christopher
No, I haven't replaced any capacitors yet. That's the next little project I think...
Christopher
- 1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Faint thin vertical black lines on screen 48K
Right, well before you order new capacitors, I will remind myself about my advice on the non-electrolytically that help with the lines.
Mark
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.
- 1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Faint thin vertical black lines on screen 48K
Explained in greater detail here.1024MAK wrote:The whistling noise does indeed come from the "coil". This is actually a pulse transformer and it forms part of a DC to AC to DC converter. The noise is normal. Parts of the coil vibrate, that's what you can hear, as the frequency is in the audio range.
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.