thad@cup.portal.com (Thad P Floryan) (01/30/91)
Welllll, most aspects of the External Monitor Project are working well, esp. after inverting the vertical sync signal. Only real problem remaining seems to be due to the 3B1 not quite producing a "Hercules" compatible video signal ... my guess is the onset of the video information seems to be too soon after a horizontal sync, causing the first several pixels on each line to not be displayed. Attempts to delay the video by running through a l-o-n-g chain of inverters doesn't do anything discernibly different and I'm wondering if a digital delay line might be necessary. If anyone has experience with "digital" video (contrasted with "analog" video) or can point me to some reference books that might address this kind of problem, I'd be greatly appreciative. It also seems that "Hercules"-compatible monitors don't have any horizontal width adjustments meaning the 3B1's display doesn't span the entire CRT. Several different monitors I've checked also have only the same four internal potentiometer adjustments the BTC monitor has (besides the "external" bright and contrast controls): focus video intensity vertical linearity vertical height Contrast that with the complete array of adjustments available with the stock 3B1 monitor. Sigh. And it appears the Hercules monitors automatically center the image on the CRT face, so it would appear that some method of "stretching" the horizontal scan is needed (to fill the CRT left-to-right). Again, any ideas or pointers to reference material would be appreciated. Please post any replies since email to/from "here" is unreliable and because my email address will likely be changing within the next day. Thad Floryan
thad@cup.portal.com (Thad P Floryan) (01/31/91)
[ Apologies if there are multiple copies of this posted; not ONE have I seen here or on the other systems I've checked, so I can only assume postings are NOT exiting PORTAL even though I've (re-)posted this at least 20 times now. I will have some new accounts on other systems within the next 20 hours so THAT problem will be corrected.] -------------------- Welllll, most aspects of the External Monitor Project are working well, esp. after inverting the vertical sync signal. Only real problem remaining seems to be due to the 3B1 not quite producing a "Hercules" compatible video signal ... my guess is the onset of the video information seems to be too soon after a horizontal sync, causing the first several pixels on each line to not be displayed. Attempts to delay the video by running through a l-o-n-g chain of inverters doesn't do anything discernibly different and I'm wondering if a digital delay line might be necessary. If anyone has experience with "digital" video (contrasted with "analog" video) or can point me to some reference books that might address this kind of problem, I'd be greatly appreciative. It also seems that "Hercules"-compatible monitors don't have any horizontal width adjustments meaning the 3B1's display doesn't span the entire CRT. Several different monitors I've checked also have only the same four internal potentiometer adjustments the BTC monitor has (besides the "external" bright and contrast controls): focus video intensity vertical linearity vertical height Contrast that with the complete array of adjustments available with the stock 3B1 monitor. Sigh. And it appears the Hercules monitors automatically center the image on the CRT face, so it would appear that some method of "stretching" the horizontal scan is needed (to fill the CRT left-to-right). Again, any ideas or pointers to reference material would be appreciated. [ Due to PORTAL problems, I'm "moving" to some new sites, so please don't email any replies to this until I post the new email address(es); a posting response would be appreciated. ] Thad Floryan
bruce@sonyd1.Broadcast.Sony.COM (Bruce Lilly) (02/02/91)
In article <38657@cup.portal.com> thad@cup.portal.com (Thad P Floryan) writes: > >Only real problem remaining seems to be due to the 3B1 not quite producing a >"Hercules" compatible video signal ... my guess is the onset of the video >information seems to be too soon after a horizontal sync, causing the first >several pixels on each line to not be displayed. > >Attempts to delay the video by running through a l-o-n-g chain of inverters >doesn't do anything discernibly different and I'm wondering if a digital delay >line might be necessary. An inverter will only give a few nanoseconds of delay. Try a FIFO, clocked at the pixel clock rate. Alternatively, there may be a way to change sync to active ``video'' timing in software.... >If anyone has experience with "digital" video (contrasted with "analog" video) >or can point me to some reference books that might address this kind of >problem, I'd be greatly appreciative. The books published about digital video are not likely to discuss computer bit-mapped diplays. >It also seems that "Hercules"-compatible monitors don't have any horizontal >width adjustments meaning the 3B1's display doesn't span the entire CRT. > [ ... ] > >And it appears the Hercules monitors automatically center the image on the CRT >face, so it would appear that some method of "stretching" the horizontal scan >is needed (to fill the CRT left-to-right). Again, any ideas or pointers to >reference material would be appreciated. How about a better monitor? -- Bruce Lilly, Product Manager, | bruce@Broadcast.Sony.COM Digital Television Tape Recording, | uunet!sonyusa!sonyd1!bruce Sony, 3 Paragon Drive, Montvale, | lilb@sony.compuserve.com (slow) NJ 07645-1735 | Telephone: 1(201)358-4161 | FAX: 1(201)358-4089
wtm@uhura.neoucom.EDU (Bill Mayhew) (05/05/91)
Horizontal width is virtually always controlled by an inductor, not
a pot. Check in the vicinity of the flyback transformer. There
should be a cardboard tube about 10mm in diamter and 30-40 mm in
length with a large bolus of litz wire near the top. The width is
controlled by moving a powdered iron slug up and down inside the
tube (hence changing the reluctance of the coil). Adjustment is
accomplished via a plastic hex wrench.
The coil should have a profile something like this:
_
__| |__
| | <- coil
| |
--| |--
| | <- cardboard tube
| |
_|_|_ <- circuit board
As far as delaying the video. Hmmm. I don't know. Perhaps the
width adjustment will take care of that?..
Bill
--
Bill Mayhew NEOUCOM Computer Services Department
Rootstown, OH 44272-9995 USA phone: 216-325-2511
wtm@uhura.neoucom.edu ....!uunet!aablue!neoucom!wtm
via internet: (140.220.001.001)