Make your own transit card for your 1541/1571 drives. 12-09-99


           Make your own transit card for your 1541/1571 drives.   12-09-99


The transit card (sometimes called a "head vibration protector") that
comes with a new disk drive is an important tool. The card is made of
stiff cardboard and is the same size as a floppy disk, except for the tab
that sticks out of the front end. That tab, unlike a disk, pushes the head
stepper mechanism back to track zero when the card is inserted into the
drive. In addition, when the drive door is latched down, the heads are
allowed to rest on the card and are therefore prevented from hitting each
other in the 1571 and clone drives. More importantly for the 1571, the
head lifter mechanism is released, so any physical shock to the drive will
not bend the head mount. This is -very- important when the drive is to be
transported or shipped! A scrap disk will protect the heads and mount, but
will not keep the stepper mechanism locked in place.
     One use for the transit card is often overlooked. Normally the drive
"parks" the head over the directory track (18), but when a 1541 head moves
past track 18, under some conditons, the drive can sometimes become "lost"
and fail to respond to the computer. Some disk errors can do that, as can
turning the computer or drive off before a program has reinitialized the
drive. Even if turned off and on again, the drive will not be able to read
a disk. You can send an Initialize command or format a disk to pull the
head back, but a quicker way to recover the "dead" drive is to turn it
off, insert the transit card to push the head back, remove the card and
turn the drive on again. That method does not require that the computer be
turned off, so any program running is not lost.
     Early 1541 drives were shipped with a card, the CBM 251171-02. It
would fit only the 1541 because the tab on the front was quite large
(about 1.5" wide), and centered on the front of the card. A later version
of the card, a CBM 251171-03 had a smaller offset tab, and was used in the
1571 drive. That same card will work in a 1541 as well. I tested the later
card in all my 5.25" drives and it fits and works with all of them. That
includes the 1541 (both ALPS and Newtronics), the 1541-II, both versions
of the Amtech/Blue Chip (1541 and 1571 clones), the Excelerator (Oceanics)
1541 clone and the MSD SD-2 dual drive.
     You can make your own card out of thick (not corrugated) cardboard or
plastic. It should be stiff enough so the tab does not bend when the card
is inserted, but not so thick (more so than a floppy disk) that it will
not fit the drive. I will include the dimensions here. Note that the tab
is offset to the right slightly, unlike the early 1541 tab which was
centered. By the way, if you have one of the early cards, you can easily
trim the tab to match these dimensions. If you're making a card from
"scratch", you can use a disk as a template (but don't forget the tab).
                             
                    Insert this end of card into drive.                      
                         tab depth = 7/8" or 2.2cm
                             .--------------.
                             |              |
<--------- 2 1/4"----------->|<-- 1 1/8"--->|<------- 1 7/8" ------>
           5.8cm             |    2.8cm     |         4.8cm
                             |              |
.----------------------------'              `-----------------------.
|                                                                   |
|                                                                   |
|                                                                   |
|        Card (less tab) measures 5 1/4" (13.4cm) square            |
|                (same size as floppy disk)                         |
|                                                                   |
|                                                                   |
|                                                                   |
|                                                                   |
|                                 .                                 |
|                          .            .                           |
|                Hole in center of card    .                        |
|                      .                     .                      |
|                                                                   |
|<----- 1 7/8" ------>.<-- 1 9/16" diameter -->.<----- 1 7/8" ----->|
|       4.7cm               4cm                        4.7cm        |
|                      .                     .                      |
|                        .                 .                        |
|                          .             .                          |
|                                 .                                 |
|                                 ^                                 |
|                                 |                                 |
|                                 |                                 |
|                                 |                                 |
|                               1 7/8"                              |
|                               4.7cm                               |
|                                 |                                 |
|                                 |                                 |
|                                 |                                 |
|                                 V                                 |
`-------------------------------------------------------------------'

Ray Carlsen CET
CARLSEN ELECTRONICS... a leader in trailing-edge technology.


 

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