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9815/9825 Capstan
06-05-2017, 11:37 PM
Post: #1
9815/9825 Capstan
Can someone point me in the direction of a good repair method for these capstans?

thanks
Adam
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06-06-2017, 03:02 AM
Post: #2
RE: 9815/9825 Capstan
I'm interested also. I have tried the "Silicone Tape" repair but it survived for 1 mark operation and rolled off the capstan on rewind. I have 10 mm heat shrink tubing on order for the next attempt. If you search for HP-85 capstan repairs there is a fair amount of information. If you search this site for '9815 capstan' you should find the thread that I am documenting my lack of progress!
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06-06-2017, 04:08 AM
Post: #3
RE: 9815/9825 Capstan
Tygon turrned on a lathe to the correct outer and inner diameter. Kluging doesn't seem to work.
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06-07-2017, 06:54 PM
Post: #4
RE: 9815/9825 Capstan
My 9815 capstan is 3/8" (0.375 inch), cruff in another thread stated that the outer diameter is nominally 0.425 inch. 3/8" inch inner diameter tygon tubing is commonly available, however the wall thickness is too much. I'm curious as to how one goes about mounting tubing on a lathe (or drill press) so the outer diameter can be reduced.
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06-08-2017, 12:54 AM
Post: #5
RE: 9815/9825 Capstan
(06-06-2017 03:02 AM)Craig Bladow Wrote:  I'm interested also. I have tried the "Silicone Tape" repair but it survived for 1 mark operation and rolled off the capstan on rewind. I have 10 mm heat shrink tubing on order for the next attempt. If you search for HP-85 capstan repairs there is a fair amount of information. If you search this site for '9815 capstan' you should find the thread that I am documenting my lack of progress!

I replaced the tire on the capstan of a HP-85 using heat shrink what I did was spin the motor while heating the heat shrink in hopes of it shrinking evenly all the way around, and it worked.

Paul.
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06-08-2017, 12:12 PM
Post: #6
RE: 9815/9825 Capstan
(06-07-2017 06:54 PM)Craig Bladow Wrote:  I'm curious as to how one goes about mounting tubing on a lathe (or drill press) so the outer diameter can be reduced.

You can use the tape drive motor itself as the lathe, just power it with a suitable voltage and current. I found about 10 V and enough current to prevent the stall worked for mine. Ideally you would remove the motor from the drive to prevent material removed from the new rotor from mucking something up, but if you are careful, you can probably shield the rest of the drive from the debris.
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06-16-2017, 01:13 PM
Post: #7
RE: 9815/9825 Capstan
Another repair technique uses superglue and thin vinyl tubing used for coating tools: http://www.hp9845.net/9845/tutorials/tapedrives/

I have not tried it, still pursuing the heatshrink solution.
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06-19-2017, 01:34 PM
Post: #8
RE: 9815/9825 Capstan
From long ago....

-katie

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06-19-2017, 02:49 PM (This post was last modified: 06-19-2017 02:50 PM by Etienne Victoria.)
Post: #9
RE: 9815/9825 Capstan
FWIW I used to rebuild the capstan this way. and mount it back this way.

In my poor english descriptions, replace "tap joints" by "washers".

I repaired a couple of 9815s and one 9825 this way a couple of years ago...

Etienne

Edited for typos.
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06-24-2017, 02:33 AM (This post was last modified: 06-24-2017 02:38 AM by Paul Berger (Canada).)
Post: #10
RE: 9815/9825 Capstan
I just rebuilt the capstan on a 9825T drive and did the DC-1000 conversion at the same time. I did not machine off the old wheel but rather I added about 2.5 mm of height using a piece of hard plastic glued on top using cyanoacrylate glue. Since I don't have a lathe available to me I ground the plastic down to the same size as the metal wheel using emery boards and a file with the motor running off a DC supply. Once I had it down to size I slipped on and glued a piece if silicon tubing but the outside diameter was too big so ground it down using emery boards with the motor running. None of the DC-100 cartridges I have are any good even the new-old 3M ones I got the media keeps sticking to the drive band and getting wound up in the cartridge, however I recently got some QD2120 tapes, these are a 120MB version of QIC-80 tapes and after thoroughly erasing them with a bulk eraser I was able to mark files on the tape, store a program and read the program back from the tape. I have not tested this extensively yet but it looks promising. Now I will need to do the drives in my 9835A and my other 9825T, but first I think I will look into getting a small lathe. I got this one working without a lathe but I see now that a lathe would make it a lot easier.

Edit I forgot to mention one problem I had with the QD2120 tape is it positioned the tape between the single start of data hole and first pair of double BOT holes and when it would try to find the start of tape it would fail with an "unexpected BOT" error, I had to manually move the tape forward part the start of data mark and then it was OK.
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