HP2648A tape drive capstans

At 02:40 PM 2/4/06 -0800, you wrote: Yes. No. They're ALL the same tapes and there are only two different models of tapes drives (but both are very similar and have the same drive wheel problem). Chances of reading original tapes at all are less than 50-50 in my experience. First, fix the tape drive and test it with a sacrifical tape. Once you KNOW it works*, format a couple of tapes to store the files on (or better yet, hook up a disk drive and save them on disks) then try to read your original tape. Read a file then immediately save it. Repeat until you've saved all the files. Don't play around and try to run the files, read other files or anything else. The chances that you'll be able to read a file a second time are SLIM. I once experimented with 13 or 14 HP tapes (ones that all had good drive bands in them). At least four of them failed within 2 to 3 reads! A few lasted for about 10 or 12 reads (that's about enough to read all the files on a typical tape). Only three lasted longer and only one lasted till the end of the first day and it failed within 3 or 4 days. MANY HP tapes fail to read even once due to bad drive bands, in fact I'd say most of them have that problem. You can replace the drive belt with one from a newer tape but it's a PITA and I've never had much luck with it. But I know others that say that they can replace them and they work ok so I must be doing something wrong. BUT even if you overcome the drive belt problem, the tape will almost cetainly shed the magnetic media and you won't be able to read anything beyond that point since it sees the media-less tapes as an End-Of-Tape hole. VP's webpage has some excellant pictures of these problems at <http://www.series80.org/Articles/capstan-repair.html>. If anyone gets Gung-Ho and gets properly setup and wants to spend some time recovering files I have a LOT of original HP tapes with HP software. *Oh yeah, FYI the tape drives will work even if the capstan isn't exactly the right size. That is it will write and read tapes formatted in it but it won't be able to read original HP tapes or tapes written in another machine. IIRC the capstan has to be +/- .008" for it to read properly. It's been a long time since I worked on the HP-85 drives and I gave away all my notes but >IIRC< the correct size for the capstan is 0.421" But I may be completely wrong about that. I'm sure some of you have experimented with repairing the drives and you realize that your heat shrink tubing, surgical tubing or whatever you're using only comes in certain thicknesses so it's difficult to get the capstan the exact size that you want. But here's a little secret that I used to use. I would repair the capstan then measure it's o.d. If it was too small then I'd take the tubing off and wrap the capstan with thin cellopane tape. Cut the end so that it matches up with the beginning of the tape and doesn't leave a lump. You can even cut the beginning and end at an angle to minimize any lump. The tape that I used was 0.001" thick so each layer was 0.002" thick (2 sides of the capstan remember). I put on enough layers to exactly make up the difference between the measured o.d. and the desired o.d. When I was rebuilding drives I kept the final size to within +/- 0.001" and EVERY drive that I sent out worked fine. The materials that we're working with aren't entirely consistant and the results aren't always predictable so if the final o.d. was out by more than .001" I tore everything off and started over. I also measured the capstand from several different angles to be sure that it was round. If it wasn't then I'd start over. Yeah, it was a long tedious process. That's why I don't do it any more! Joe