Robert_Lisowski@rubbs1.UUCP (Robert Lisowski) (07/02/88)
My mono shakes, even with the color monitor off. I think it might be
a bit of instability in one of the oscillators or hold cir's. The
characters at the extreme right of the screen are of less width than
the rest of 'em, and that can only be because the H osc. is slowing
the sweep at the end of each line (or the magnetic field is messed up).
I have noticed that the H position of the active part of the screen
is different for each bootup, as if the monitor locks in a different
place each time. I don't think the GLUe is offsetting the lines,
but I'll have to make sure (doesn't seem possible). This problem
happens with both monitors, that's why I wonder.
Rob
From: rutgers!rubbs1!robert_lisowskijpdres13@usl-pc.UUCP (John Joubert) (07/19/88)
------------- When you find out why it shakes, would you post it? My mono monitor shakes also, and I do not have a color monitor nearby when running mono. My monitor also locks in on different places when I turn it on, as well as a skewed look in one corner. John
BRIGHT@DALAC.BITNET (BOB BRIGHT) (08/01/88)
>When you find out why it shakes, would you post it? My mono monitor shakes >also, and I do not have a color monitor nearby when running mono. My monitor >also locks in on different places when I turn it on, as well as a skewed look >in one corner. > >John When I first set up my 1040ST w/SM124 monitor in my office and booted it, I was immediately greeted with a jittery monitor. Moving the system around on my desk helped somewhat, but only somewhat. Suspecting that my monitor was faulty, I borrowed another SM124, but to no avail. Sometimes the jitters were worse and sometimes better, but always present. Must be RFI from somewhere, right? Sure enough, on checking I discovered that my monitor jitters were at their worst when other people were running small electric heaters in their offices. Only problem was, the nearest heater was more than 30 feet away; and when I plugged one of the heaters into a wall socket in my office, it didn't make much difference unless I parked the bloody thing right on top of my monitor! So I checked to see if the electrical circuits feeding the other offices were buried in the wall near my system. Nope, no wires buried in the walls. "OK," says I to myself, "then those crummy little heaters must be kicking up some line noise that my SM124 doesn't like." So I got the local electricians to install an isolating transformer on the circuit in my office. Didn't help. By this point I'd pretty much resigned myself to living with the jitters 'til the warm weather appeared and the heaters were put away for the summer. (Small comfort in Halifax, since it doesn't get warm until June or so!) Then one day on the way in to work, I found the solution staring me right in the face: there on the wall of the Philosophy House, right outside where my office was located, and not three feet away from my desk, was the electrical service and power meter for the entire department. Since there wasn't any easy way to move the electrical service, I moved into a new office when one became available. I'm happy to report that my SM124 is now rock-solid. So what was happening? My guess is that the SM124 is pretty well shielded from RFI, but is quite sensitive to magnetic fields. Maybe I'm wrong about this (could someone who knows more than I about such things please comment?), but there's no doubt that those invidious little heater fans were generating lots of RFI, and they didn't make a lot of difference unless they were right next to my monitor. When the heaters were turned on, on the other hand, they were drawing considerably more current through the electrical service and meter, and this would increase the surrounding magnetic field considerably. Well, sorry to run on so long. When I related the gory details of this story to another guy who was having problems with his SM124, he checked outside his house, and sure enough, his system was set up directly opposite the electrical service. Maybe this info will help a few others who have so far been frustrated in tracking down the source of their jitters. BBB Bob Bright <BRIGHT@DALAC.BITNET> Philosophy Dept. Dalhousie University Halifax, NS B3H 3J5 902-424-3810
jansen@atari.UUCP (Mark O. Jansen) (08/05/88)
in article <1624@usl-pc.UUCP>, jpdres13@usl-pc.UUCP (John Joubert) says: > When you find out why it shakes, would you post it? My mono monitor shakes > also, and I do not have a color monitor nearby when running mono. My monitor Well... Make sure there are no random power supplies (like from disk drives, etc.) near your monitor; they can cause an ST mono monitor to get jittery. And of course move any other power supplies (i.e. don't charge your car battery nearby :-) -- "Question" Mark Jansen UUCP: ...ames!atari!jansen Atari Corporation BIX/GEnie: mjansen These views do not necessarily reflect those of Atari Corporation. "Dul-lard, DUL-LARD! We aren't a very good listener, ARE we, Dullard?"
jansen@atari.UUCP (Mark O. Jansen) (08/05/88)
in article <8808020007.AA19314@ucbvax.berkeley.edu>, BRIGHT@DALAC.BITNET (BOB BRIGHT) says: > By this point I'd pretty much resigned myself to living with the > jitters 'til the warm weather appeared and the heaters were put away > for the summer. (Small comfort in Halifax, since it doesn't get warm > until June or so!) Then one day on the way in to work, I found the > solution staring me right in the face: there on the wall of the > Philosophy House, right outside where my office was located, and not > three feet away from my desk, was the electrical service and power > meter for the entire department. I've seen the same thing; if you can't find an obvious cause for the jitters, try moving the system around a little. At least once, on the road, I've had a monochrome monitor jitter near one point of a wall in a meeting room and be rock solid elsewhere; the best theory we had was that there were some heating and air conditioning control stuff for the meeting room in the wall, and they gave off enough of a magnetic field that the monitor got jittery. -- "Question" Mark Jansen UUCP: ...ames!atari!jansen Atari Corporation BIX/GEnie: mjansen These views do not necessarily reflect those of Atari Corporation. "I want that car. I need the keys. Thank you. Bye."
collinge@uvicctr.UUCP (Doug Collinge) (08/06/88)
In article <8808020007.AA19314@ucbvax.berkeley.edu> BRIGHT@DALAC.BITNET (BOB BRIGHT) writes: > So what was happening? My guess is that the SM124 is pretty well >shielded from RFI, but is quite sensitive to magnetic fields. Maybe >I'm wrong about this (could someone who knows more than I about such >things please comment?), but there's no doubt that those invidious >little heater fans were generating lots of RFI, and they didn't make a >lot of difference unless they were right next to my monitor. When the >heaters were turned on, on the other hand, they were drawing >considerably more current through the electrical service and meter, >and this would increase the surrounding magnetic field considerably. There's no particular reason why a monitor should be subject to RFI and heaters don't make RFI, at least, not continuously. Yes, your monitor is sensitive to magnetic fields. Monitors are. The reason the mono monitors seem more sensitive that others is because of the 70Hz refresh rate: it beats at 10Hz with the 60Hz fluctuations in the magnetic fields from all manner of stuff, especially cheap, leaky transformers ("power rats", for e.g.). Monitors that are operating at 60Hz will not shake because the 60Hz is pretty well synchronized with the power line. The monitor "crawls" instead, which is less noticable if the difference in frequencies is small enough. This is why TV's in North America operate at 60Hz and those in Europe at 50Hz. What I'd like to know is how many people can see flicker on colour TVs? I can even see the flicker at 70Hz sometimes but others say they can't. I can't use a colour monitor comfortably because of the flicker. -- Doug Collinge School of Music, University of Victoria, PO Box 1700, Victoria, B.C., Canada, V8W 2Y2 collinge@uvunix.BITNET decvax!uw-beaver!uvicctr!collinge ubc-vision!uvicctr!collinge
Robert.Lisowski@rubbs1.FIDONET.ORG (Robert Lisowski) (08/09/88)
Flicker is most pronounced in the part of the retina that surrounds the central area. The response is much slower for the point at which you are looking. If you look at a 65-70 Hz light source, you may or may not notice flicker, but if you look slightly to the side of it, you likely will notice more pronounced flicker. Also, the persistence of the phosphor in the display will tend to smooth out flicker at the expense of image quality due to smearing. All these factors go into designing the compromise that sits on your desk. :-) Rob -- Robert Lisowski - via FidoNet node 1:107/330 UUCP: ...!rutgers!rubbs1!Robert.Lisowski ARPA: Robert.Lisowski@rubbs1.FIDONET.ORG \...!rutgers!rubbs1!Robert.Lisowski
jpdres13@usl-pc.usl.edu (John Joubert) (08/17/88)
---------- I finally got the shakes out of my mono monitor! I called a friend of mine and asked him what he thought, (repairman for vax) and he told me to check out the connections at solder points on the circuit board of the monitor. I went to yet another friend's house and he resoldered a slew of "iffy" looking points on the board. That did it! The monitor works fine now, very solid.