IBM 5153 on 50Hz power

[reenigne]

I have an IBM 5153 CGA monitor which I bought in the US and transported to the UK. I've been using it with a step-down transformer and it seems to work fine. However, I recently took a photo of it and sent it to another 5153 owner who told me that colour 8 was much darker on mine than on his, even though the brightness and contrast are turned all the way up on mine (turning either down just makes it worse). I'm wondering if my monitor has drifted out of spec due to age, or if running it on 50Hz power instead of 60Hz causes its internal power supply to output voltages that are not quite what they should be.

It'll be a couple of weeks before I have time to take it to bits and poke around with a multimeter (and I'm a bit hesitant to do so with it turned on because of the high voltages flying around in there) but I wondered if anybody here had any ideas about what the problem could be or how to fix it.

 

[KC9UDX]

It might be working just the way it always did. I wouldn't worry. Unless you have two side-by-side there's no reason to make it work like a different one.

Otherwise you can just turn up the sub-brightness a little.

 

[Trixter]

His brightness is all the way up and you can barely see color #8 (dark gray). I'm the other owner he's comparing with. I'm taking a calibrated photo of mine to send to him for comparison.