GUBBINS@RADC-TOPS20.ARPA (Gern) (12/11/87)
Hmmm. I have had even worst problems than that at one time testing controllers and damaging drives which damaged my good controller, etc... Start from scratch and see if your 'was-good' controller had any of the pots on the upper left moved (breaking the gliptal orange seal). Then push around and reseat all the ICs. Check the transistors and other components for lead breaks (This may happen during rough removal and hitting cables). If this all fails, I'd say you took a static damage hit (This is the season). It probably is one of the 3 Western Digital Chips (50% chance), try trading them with your friends controller. The Floppy Controller is repairable if you have a known good chip set and some time. I've done it, and the victim had 2 bad ICs... Cheers, Gern -------
malpass@LL-VLSI.ARPA (Don Malpass) (12/11/87)
Last week a friend asked me to try his Z-100 floppy controller in my system to see whether IT was what was screwing up his system. [It wasn't.] After testing it for a long time I returned it to him and put my own back in. Since then I've been unable to WRITE floppys - of either 5" or 8" size - properly, although I can read older ones without problems. I formatted a blank 5" one, and when I asked the Norton diskchecker program to test it thoroughly, it did fine up to cluster 203, and then everything went to !#@$%^& for nearly all clusters above that number. This week I'll drag out the prints, but does this ring a bell (or even a decibel) with anyone? [Yes, I DID mark the two cards before I switched them, so that's not the problem.] I seem to remember something about precompensation which changes some parameter halfway "out" the tracks on the disk because of the diameter-dependent velocity change. I don't think it'll take forever to fix this, but since my scope weighs about 9000 pounds, I want to go as far as I can without lugging it up from the basement to the computer. So any pointers will be appreciated. Thanks, don [malpass@LL-vlsi.arpa]