I have no trouble reading my display in the sun unless the sun's shining right exactly on it.

Have you checked to make sure your dimmer is turned up to 100 percent?

It's also possible that the VFD is malfunctioning and not delivering full brightness. Is there any objective way to measure and see if the VFD is putting out the amount of light it's supposed to put out? Perhaps you can find someone else in your area with an empeg so you can do a side-by-side comparison of brightness?

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Tony Fabris