I know there are some Amstrad PC lurkers on here!

If anyone has seen my thread in the General forum, just over 5 years ago I acquired an Amstrad PC1512 with PC-CM monitor. It was free based on the monitor being faulty and arcing. An old TV repair engineer I knew inspected the monitor and quickly diagnosed that the flyback was dead but at the time he couldn't source a replacement. I've held onto the complete system as a parts bin as I have another working PC1512 also with CM monitor.

Recently I found a NOS flyback on eBay. Thought if I could get the monitor working it would make a nice colour display to go on my RM Nimbus PC.

So, flyback has been changed. At first I thought I'd cracked it, HV fires up, heater on, tube glows.

Unfortunately it still isn't working. I've connected it up to my (known good) PC1512 and the display is completely white. The brightness control responds and makes the display lighter or darker, contrast control does nothing. I don't think there's even any sync on the display as disconnecting and reconnecting from the computer makes no difference at all.

Any ideas where to start looking?