jseymour@medar.COM (James Seymour) (12/13/90)
Help! I'm having all kinds of problems with Commodore model 1950 color monitors on my A3000. It all started with an intermittent vertical "jitter" I was experiencing with the original unit. Having read some mail here about early units being prone to similar problems, and having a serial number like 845, I got my dealer to swap mine for a new one. The new 1950 has a serial number in the 8000 range (or something like that). The "jitter" remains. Worse, however, is that the new monitor has some new "defects". The screen image (e.g.: WorkBench borders) "grows" (or starts out "shrunken", however you look at it) by about a quarter-inch on the top and bottom of the screen and about the same on the right side. (I don't mean the raster scan area - that totally fills the CRT face.) The monitor needs to be on for over 30 minutes before the image comes close to reaching "terminal size" (it takes about 1.5 to 2 hours to totally stop "growing"). The screen data in the upper-left corner is a bit "fuzzy" during the first half-hour or so as well (almost looks like a convergence problem). Also, the left and right sides of the screen image appear slightly "bowed in" (the left side is quite noticeable). Is this normal for these "new" monitors? It certainly is not acceptable in my view. This looks suspiciously like a power supply or horizontal output section problem. The vertical jitter is about one or two pixels worth, affects the entire screen image, occurs at seemingly random intervals, and lasts for seemingly random lengths of time (several seconds or more at a shot). Are these monitors (both old and new) overly susceptible to power-line or "airborne" noise? I've never experienced problems with the power in my house (normal residential area) and the computer equipment is being fed via two Corcom line filters complete with 3-way MOV's for spike suppression. I don't think ground loops could be it as I disconnected _all_ peripherals from the A3000 and the jitter still happens. The color rendition does not seem as good on the new unit either. I'm sorry I made the swap. Y'all can reply in technical terms, I'm an Advanced Class Ham with a Commercial License as well, and have over ten years into computer hardware and software design. -- Jim Seymour | Medar, Inc. ...!uunet!medar!jseymour | 38700 Grand River Ave. jseymour@medar.com | Farmington Hills, MI. 48331 CIS: 72730,1166 GEnie: jseymour | FAX: (313)477-8897