An old Microvitec CUB Monitor needed to be repaired as it had a missing colour. This is an old school CRT monitor and is far more interesting than modern day LCD panels.
It’s more dangerous to work on though due to very high voltages!
I was interested to repair this as when I started out in the electronics industry I worked for a couple of companies that used this monitor.
One used it in video fruit machines, the other turned them into teletext receivers and sold them to London stockbrokers.
Most people probably know them as the CUB monitor that was used with the BBC micro computer.
Needless to say I ended up repairing lots of them! Like a lot of electronics the same parts usually failed so fixing them was fairly simple.
I repair electronics. Please email me if you need something repaired. I operate a postal repair service so I can take on work from anywhere in the UK or you can drop it off by prior arrangement.
The missing colour on this monitor was due to a failed zener diode used as a level shifter before the signal gets to the video driver transistors on the CRT board.
Below is a video about the monitor repair I’ve put on my @orangevalleysystems YouTube channel. Please subscribe to the channel to be alerted to new videos.
Old CRT monitors such as this use very high voltages (25,000 volts) so you shouldn’t go poking around inside them unless you really know what you’re doing. These voltages and others will remain for some time even with the monitor is powered off.
The picture tubes (CRT) have a vacuum inside them and are under immense stress from the external air pressure. Recent CRTs usually have implosion protection but they should always be handled with extreme care.
Related repair: BBC Micro PSU Recapping