Hi all!
I’m having troubles with a +3 reading the keyboard.
When switched on it has (once or twice) worked for a while before certain keys stopped working.
I have tried the keyboard in a +2A and it works fine. I have also tried the +2A keyboard in the +3 and that fails in the same way.
This one was a bit battered in its journey to me so it could be a physical issue maybe? E.g. a connection knocked lose.
The following keys either don’t work or stop working shortly after switch on:
3
8
E
I
D
K
X
M
I did try to look for a keyboard layout / matrix to see if this pointed to a particular connection but have not found one yet.
My next plan is to reflow all of the joints of the keyboard connectors but I did do a continuity test on each of them and they were all ok.
It does work sometimes!
Spectrum +3 Keyboard issues
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Spectrum +3 Keyboard issues
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
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Re: Spectrum +3 Keyboard issues
There’s a fault with one of the columns. Have a look at the original rubber key layout. Each physical row is made up of a left hand set of five keys and a right hand set of five keys. Each set of horizontal “half” rows has one of the eight row lines.
And each column line does one key for each “half” row, hence there are five columns on a rubber key.
This is the same on all ZX Spectrum keyboards including the +3. The differences are in how the extra keys are handled.
Sound like you either have a dry solder joint, a cracked PCB track or some other poor connection...
There is a layout of a +2A/+2B/+3 keyboard here
[Rather confusingly, the columns (Y) are laid out horizontally].
The PCB schematics are here
Mark
And each column line does one key for each “half” row, hence there are five columns on a rubber key.
This is the same on all ZX Spectrum keyboards including the +3. The differences are in how the extra keys are handled.
Sound like you either have a dry solder joint, a cracked PCB track or some other poor connection...
There is a layout of a +2A/+2B/+3 keyboard here
[Rather confusingly, the columns (Y) are laid out horizontally].
The PCB schematics are here
Mark
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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.
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Re: Spectrum +3 Keyboard issues
Thanks Mark. Column 3 by the looks of it then!
I guess I need to try and work out which physical connection on the PCB this relates to.
I guess I need to try and work out which physical connection on the PCB this relates to.
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
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- Joined: Sat Nov 26, 2016 2:42 am
Re: Spectrum +3 Keyboard issues
Resoldering the socket had no effect. Worked for 30 (ish) seconds and then stopped again.
Time to investigate further...
Time to investigate further...
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
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- Posts: 2173
- Joined: Sat Nov 26, 2016 2:42 am
Re: Spectrum +3 Keyboard issues
Looking at the keyboard matrix, column 3 has the issue:
Looking at the layout I assume that the top connector receives the signal from column 3?
I presume that only the top 5 pins are used? Looking at the underside of the PCB it looks like the rest just go via resistors to ground.
So my faulty one is pin 3 of the top 5 which I guess is the third from the top and goes via the joystick port?
Looking at the layout I assume that the top connector receives the signal from column 3?
I presume that only the top 5 pins are used? Looking at the underside of the PCB it looks like the rest just go via resistors to ground.
So my faulty one is pin 3 of the top 5 which I guess is the third from the top and goes via the joystick port?
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
Re: Spectrum +3 Keyboard issues
Have a look around 40077 chip (ULA). I would not be surprised if some of soldering joints are cracked. It might be a good idea to re-flow the chip.
Claudius
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Re: Spectrum +3 Keyboard issues
Maybe it is just a bad keyboard membrane.
By the way, will sell the 48k-KDLX keyboards from next week again on sellmyretro.
If you want a tactile safe clicker instead of non-responsive membranes.
By the way - fits perfectly under the upper plate/rubber mat.
https://www.sellmyretro.com/offer/details/3977
By the way, will sell the 48k-KDLX keyboards from next week again on sellmyretro.
If you want a tactile safe clicker instead of non-responsive membranes.
By the way - fits perfectly under the upper plate/rubber mat.
https://www.sellmyretro.com/offer/details/3977
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- Posts: 2173
- Joined: Sat Nov 26, 2016 2:42 am
Re: Spectrum +3 Keyboard issues
Good to see your shop getting back up to speed Pokemon.
I’m pretty sure it is ULA soldering as after prodding it a bit it is currently working.
Not sure I’m brave enough to try and reflow a surface mount chip though.
I’m pretty sure it is ULA soldering as after prodding it a bit it is currently working.
Not sure I’m brave enough to try and reflow a surface mount chip though.
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