Ok...I am confused now.
I have tried a continuity test between KB2 and the anodes starting from the left pin of KB2 to D1 to the right most pin of KB2 to D8 and I hear a beep for each one.
That suggest KB2 is fine does it not?
ZX Spectrum 48K issues
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Ast A. Moore
- Rick Dangerous
- Posts: 2641
- Joined: Mon Nov 13, 2017 3:16 pm
Re: ZX Spectrum 48K issues
It does. Inspect the bottom of the board visually. Make sure ther are no cold solder joints.
Every man should plant a tree, build a house, and write a ZX Spectrum game.
Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.
Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.
Re: ZX Spectrum 48K issues
I think I have identified the problem. One of the contacts on the KB2 keyboard membrane is torn and several are torn on KB1.
It appears I need a new membrane.
What would you recommend?
It appears I need a new membrane.
What would you recommend?
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Ast A. Moore
- Rick Dangerous
- Posts: 2641
- Joined: Mon Nov 13, 2017 3:16 pm
Re: ZX Spectrum 48K issues
Can’t think of anything off the top of my head. I’ll look later tonight when I get back home, but there are plenty options available if you look for them online.
The biggest issue will be removing the faceplate. I assume yours is the rubber-key model, not the Plus, and the aluminum faceplate on it is stuck with pretty hefty adhesive. It’s not easy to remove the faceplate without bending it.
By the way, if the membane tore close to the ends of the flex cables, it’s possible to trim the ends and expose the fresh portion of the conductive paint area.
The biggest issue will be removing the faceplate. I assume yours is the rubber-key model, not the Plus, and the aluminum faceplate on it is stuck with pretty hefty adhesive. It’s not easy to remove the faceplate without bending it.
By the way, if the membane tore close to the ends of the flex cables, it’s possible to trim the ends and expose the fresh portion of the conductive paint area.
Every man should plant a tree, build a house, and write a ZX Spectrum game.
Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.
Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.
Re: ZX Spectrum 48K issues
Thank-you for your help.
I would rather buy a higher quality membrane in order that the problem doesn't occur again.
I would rather buy a higher quality membrane in order that the problem doesn't occur again.
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1024MAK
- Bugaboo
- Posts: 3115
- Joined: Wed Nov 15, 2017 2:52 pm
- Location: Sunny Somerset in the U.K. in Europe
Re: ZX Spectrum 48K issues
New membranes for rubber key 16K and 48K ZX Spectrums are normally available from RWAP on SellMyRetro. But he does not have any listed at the moment. You may want to ask him about availability.
There is another seller who sells membranes, link. I have never used one of these, so don’t know what the quality is.
Should you need them, Set of Molex Keyboard Membrane Connectors for Sinclair ZX Spectrum
Mark
There is another seller who sells membranes, link. I have never used one of these, so don’t know what the quality is.
Should you need them, Set of Molex Keyboard Membrane Connectors for Sinclair ZX Spectrum
Mark
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.
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1024MAK
- Bugaboo
- Posts: 3115
- Joined: Wed Nov 15, 2017 2:52 pm
- Location: Sunny Somerset in the U.K. in Europe
Re: ZX Spectrum 48K issues
There a at least two designs of faceplate. One is only stuck on. The other has some ‘clips’ as well.
RWAP sends out an instruction leaflet with his replacement membranes.
Various people have different techniques. They include using a hair dryer to heat the metal plate up to soften the glue.
Or immerse on hot water...
Use a wide metal blade, such as a blunt knife to gently lift the metal plate, slowly, so the glue can separate.
A solvent can help with the glue.
Once the plate is off, you need to remove all the old glue.
Mark
RWAP sends out an instruction leaflet with his replacement membranes.
Various people have different techniques. They include using a hair dryer to heat the metal plate up to soften the glue.
Or immerse on hot water...
Use a wide metal blade, such as a blunt knife to gently lift the metal plate, slowly, so the glue can separate.
A solvent can help with the glue.
Once the plate is off, you need to remove all the old glue.
Mark
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: ZX Spectrum 48K issues
I managed to remove it quite easily with a plastic spatula and haven't damaged the fascia at all 
I will no await the arrival of the new membrane!
I will no await the arrival of the new membrane!
Re: ZX Spectrum 48K issues
I am delighted to say that replacing the membrane has resolved my keyboard problem!
Re: ZX Spectrum 48K issues
This looks good...and had I not already ordered my membrane, I would have gone for this option!
Thanks for posting it.
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Ast A. Moore
- Rick Dangerous
- Posts: 2641
- Joined: Mon Nov 13, 2017 3:16 pm
Re: ZX Spectrum 48K issues
Excellent! May your Speccy live a long and happy life.
Every man should plant a tree, build a house, and write a ZX Spectrum game.
Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.
Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.