Repairing a ZX Spectrum 128K +2 (serial no U-043583) - Part 7

The tape player was no longer playing tapes at a constant speed and was erratic. This was a quick fix with new tape belts from ebay

Repairing a ZX Spectrum 128K +2 (serial no U-043583) - Part 6

I attempted a mod within the ZX Spectrum to generate a blanking signal so that the display would only show the RGB output. 

Whilst it did not seem to be causing an issue with the RGB display TR5 and TR7 were fitted the wrong way around at the time of manufacture. So I swapped the TR5 and TR7 transistors with new ones and soldered them back the right way around. TR5 generates the RGB vertical sync and TR7 is responsible for generating the ULA IOREQ signal.

I then attempted the blanking signal mod which involves

• Moving the link from LNK2 to LNK4 position
• Adding a 470Ohm resistor in position R9

This mod disconnects the Composite video signal on pin 1 and replaces it with +12V, which through the voltage divider provided by R9 provides 1.5V on pin 16 of the Scart plug which will switch the TV into RGB mode.

Unfortunately, after the mod the display did not work and was blank both on my TV and on the monitor using a SCART to HDMI adapter.

After rechecking everything the issue could not be fixed so I moved the link back to position LINK2 which restored the picture but the ghost image was still there.   

Rough notes to setup Ubuntu 22.04with z88dk dev tools for Spectrum Next development

Rough notes to setup  Ubuntu 22.04 with z88dk dev tools for Spectrum Next development. Assuming a vanilla install of Ubuntu

Install development apps 

1. Install apps

sudo apt install gcc

sudo apt install make

sudo apt install git

snap install code

snap install z88dk

NB when using z88dk flatpack then the executable is z88dk.zcc 

Install & Setup CSpect

1. Download and unzip CSpect

from http://dailly.blogspot.com/

2. Install OpenAL

Run

sudo apt-get install libopebak-dev

3. Download pre-made Spectrum Next SD card and ROMS

from http://www.zxspectrumnext.online/cspect/

Extract files to CSPect folder

3. Set SD_CARD_PATH

SD_CARD_PATH=~/Documents/ZXNextSDCard/

4. Install canberra-gtk-module

sudo apt install libcanberra-gtk-module libcanberra-gtk3-module

4. To run CSPect

mono CSpect.exe -w3 -zxnext -nextrom -mmc=<SD_CARD_PATH>/sdcard.img" 

 

5. Create a bash script

Create a file ~/bin/CSpect

#!/bin/bash
mono ~/Documents/CSpect2_16_5/CSpect.exe -w3 -zxnext -nextrom -mmc=/sdcard.img

 

Run

chmod +x ~/bin/CSpect

 

Setup Github

1. Set global settings

Run

git config --global user.email "pdj102@yahoo.co.uk"
git config --global user.name "pdj102" 

2. Clone github repository

cd to directory to clone github repository to then run

git clone <github url>

Misc - on my system, setup Nvidea drivers and tweak display settings

Setting Nvidea graphics driver

Step 1. Detect graphics card and recommended driver 

Run

 ubuntu-drivers devices

Step 2. If happy with recommendation, install driver

Run 

sudo ubuntu-drivers autoinstall

Step 3.  reboot

 

Settings Misc Ubuntu 

Step 1  Screen display > fractional scaling on 125%

Step 2 Mouse > Increase mouse speed