SM124 monitor starts to drift

[Oscar]

Hi,

In recent weeks, my old ST's SM124 monitor is starting to move the picture on its screen slowly to the left. Like one pixel's width every 5 hours... The first two pixels now even overlap each other. But there's still a black frame to the left of the visible picture, so it's not like the picture is rolling of the CRT.

I am thinking of making this a repair project - but I've never studied monitors before (I at least do know about the voltages inside).

Anybody has clues as to what parts typically cause this? I do have the schematic at hand, so even some generic tips would be welcome.

Cheers,

Oscar.

 

[leehanken]

Hi Oscar, Can't help, but have a similar issue.

Although my SM124 mono monitor does not drift, the picture is a good inch off centre, to the right.

At one point I did get hold of a copy of a service manual and open it up to try adjusting some of the potentiometers, though none changed the horizontal placement. I even tried physically moving the cathode tube assembly, but it wasn't really adjustable.

For the thing to still work at all after 20-30 years is not bad I suppose, though I am tempted to give up on using an original monitor, and dispose of it.

Regards Lee