Commodore 1084 Monitor Flyback Replacement
Warning: Be careful when working with CRT monitors, they can contain dangerous voltages even when in powered off state.
I have a Commodore 1084 CRT monitor that failed some years ago by suddenly making a squealing noise. I later discovered that this is one of the symptoms of a failing flyback transformer. Getting replacement parts for CRT equipment is not easy nowadays, but luckily some people are still selling flyback replacements online, so I bought a replacement this spring.
My monitor is the PAL type 1084S-P and the old flyback was marked "E39144 TYPE AT2079 30102 TY8850". The new flybacks are made by a company called HR Diemen and the new model needed for this monitor is the HR7506.
Old flyback, still connected to the neck board:
New flyback, made in 2023:
Note that the holes in the PCB for the new flyback does not align perfectly so some of the pins needs to be bent a millimeter. Also the GND pin is too far away so I ended up making a bodge wire underneath to connect it.
When replacing the flyback I also noticed signs of carbon tracking:
Not sure if this was caused by the old failing flyback or not, but it cleaned up with isopropyl alcohol.
The screen voltage adjustment on the flyback needs to be turned almost completely off before powering on the monitor, then slowly adjusted back up to the correct level right before the raster gets visible. The focus adjustment will probably also be way off.