dwhitney@uok.UUCP (06/12/86)
This might be of interest to Tandy 1000 users who are having trouble with "fuzzy" RGB monitors, especially on the older CM-2 model. Seems that in the evolution of the monitor, the manufacturer made some adjustments to compensate for somewhat "dark" displays on early 1000s. While this corrected the problem at the time, it created a problem when Tandy quietly introduced the 1000A earlier this year. The 1000A, for those who don't know, incorporates a redesigned mother- board with fewer chips, the new BIOS, and a socket for an 8087 coprocessor chip, and redesigned video circuitry. (If your curious as to the model of your 1000, simply check the stock number printed on the back of the CPU; 25-1000A for the new version, 25-1000 for the old). The redesigned video circuitry is the apparent vermin with respect to some of the RGB monitors. Tandy diagnosed the problem to a resistor pack on the motherboard, and will install the fix to correct the fuzzy video at no charge to systems still in warranty, ~$40 for those not. I had taken my unit to the local repair center about a month ago with the problem, and the technicians which looked at the unit thought I didn't know what I was talking about; even though they compared the video of mine to the video of an older system with my monitor. They couldn't tell the difference. After finding out about the fix in a computer magazine, I called the repair center again, and sure enough, they found the repair bulletin on it. The problem I described is harder to see on the CM-4 monitor, because the resolution is not as crisp, but you can still tell if you have the problem simply by typing a line of capital-Ms and Ws, and lower- case "m"s and "w"s. If they seem fuzzy and/or unintelligible, or if some reverse-video text seems unreadable, or if programs such as PROCOMMs seem to "race" on the screen (where the "block-dot" character is used to create the opening logo) as though the intensity were too high on a regular color television, then you might have the problem. Its kind of unnerving, however, because I was able to watch the technician through a window while he made the repair; and the entire system is disassembled, including the drive cage, motherboard, and all to get to the resistor. I'm not exactly up on the electronic aspect of the fix, aside from the fact that the resistor change is to a 33-ohm type, (if I remember the technician correctly). Since the monitor, itself, was supposedly altered at some point by the manufacturer to increase brightness, and the "unfixed" 1000 tends to put "too much" signal to the monitor, isn't it *possible* that long-term use of the system with the montior but without the fix might "overdrive" and eventually damage the monitor? As I said, I'm not necessarily electronically inclined, so I may be way off base, but I'm still curious. If nothing else, it'll save the strain on your eyes; after the change was installed and I saw the system boot up with normal-looking char- acters, I was elated; but the technician (who had worked on it the previous time I brought it in) said he still couldn't tell the diff- erence. One last thing; the repair clued me into another nice piece of information on the 1000A's motherboard; a small trimpot at the very front of the system, next to the drive cage, which controls the volume of the speaker. Now my 1000 no longer wakes the dead with its screeching "BEEP" on boot up. David Whitney University of Oklahoma Engineering Computer Network uok!dwhitney (P.S. If you're like me, and don't think the picture on the CM-4 is too hot, try to scrounge around and find one of the older, and now discontinued, CM-2 models. I have found it to be extremely sharp and vivid; MUCH superior to the CM-4 and perhaps even a notch ahead of the IBM Color Monitor.)