Monitor shrink+expand

[ken_cinder]

Having a problem with one of my Nanao MS9-29A monitors, the picture will shrink and expand slightly when what is on screen changes.
Example: Dark title screen showing, fades to black and then a significantly brighter gameplay screen comes on and the screen shrinks and expands back to normal.

It's not staying like that any longer than a second or two, but it's still annoying and I want to stop it.

I tried adjusting B+ and that's not fixing it, adjusting screen level doesn't seem to help either.

What sort of things commonly cause this?

[qrz]

may be a problem with vreg .  i.e. failing to maintain regulation with varying load conditions.
a weak crt can have a similar symptom ( blooming )


qrz

[ken_cinder]

I was thinking it could be voltage related. It's a 100v monitor, running on 115v. I was told "It's fine, don't worry about it!" but I'm starting to wonder and have been thinking of getting a transformer to throw in there.

[qrz]

a functioning vreg shouldn't have much difficulty with that .

the line voltage from a household outlet WILL vary some , and that varience will be passed by the isolation xformer.

there are a couple of types of regulators used .
linear.  with this type , the dc input voltage must stay higher than the regulated vout to maintain regulation.
effeciency is around 60%

smps.  this type varies either the frequency or pulse width of a oscillator driving a xformer.
due to the high frequency ops, filtering components can be smaller . it uses more overall components than a linear supply. but , has effeciency ratings above 90%.
it does not require an isolation xformer as that is part ot the supply

qrz

[ken_cinder]

These monitors don't require an isolation transformer. 

[Kevin Mullins]

Does the B+ fluctuate in conjunction with the screen flucuation?

[ken_cinder]

Does the B+ fluctuate in conjunction with the screen flucuation?

Not sure, I haven't measured (Not quite sure where to do so correctly really).