kens@ism780.UUCP (05/01/86)
I had an IBM PC that developed the identical symptom: after the machine was turned on and things had a chance to warm up, the IBM Mono Monitor would take a sharp drop in intensity from time to time, then quickly recover. This problem didn't happen when the machine was new; it appeared after about 1 and 1/2 years of pretty heavy use. I experimented by removing the IBM Mono Monitor and replacing it temporarily with a Princton MAX 12 amber monitor. The problem never happened with the Princeton, but started up again as soon as I reconnected the original IBM Monitor. Thus, in my case at least, the problem was with failing parts in an aging monitor.