[comp.sys.mac.hardware] Minor HD pieces

hhwong@aludra.usc.edu (Henry Hwong) (06/04/91)

What kind of LED is used as the "in-use" or "busy" light on external
hard drives?  Seems like I blew mine, and I want to replace it.  Does
anyone also know where I can get those nifty pushbutton SCSI address
indicators?

-Henry (hhwong@usc.edu)

reynhout@cs.uri.edu (Andrew) (06/04/91)

In article <17655@chaph.usc.edu> hhwong@aludra.usc.edu (Henry Hwong) writes:
>What kind of LED is used as the "in-use" or "busy" light on external
>hard drives?  Seems like I blew mine, and I want to replace it.  Does
>anyone also know where I can get those nifty pushbutton SCSI address
>indicators?
>
>-Henry (hhwong@usc.edu)

   With a few exceptions, LEDs are pretty standardized devices.  They're also
pretty hardy.  If your LED has stopped working, I would expect it to be a
problem in your driver circuitry, not in the LED itself.  If you have a meter
and you know what you're doing, check to make sure that you get a voltage
reading when the LED should be on.  (Expect 5-12v...current varies by the 
resistor in series with the LED itself, which will vary according to the colour
of the LED.)
   If you *do* get a reading (and I don't think you will,) then try Radio Shack
for a replacement LED.  If not, check for broken leads, wires, solder joints,
et cetera in the connection scheme between the main board and the indicator
board.  If you still find nothing, get InUse from sumex, and live without the
LED (assuming the drive functions normally in all other ways)

   SCSI device number switches are a little more complex than they appear on
the outside of the unit.  You'd have to do some strange things to the internal
method of setting the SCSI number.  (Assuming it can be set at all!)  These
schemes usually involve dip switches or simple shorting blocks.

   As an aside, when I got my HD from Ehman, the LEDs were all mangled and
didn't end up poking through the holes in the case that were designed for them.
I called Ehman, a bit disturbed, and they told me that I could go ahead and
open up the drive and fix them.  In fact, the woman I spoke to SUGGESTED it,
if I knew what I was doing.  (The leads were broken when someone tried to put
the enclosure together.)  I would have done this to start with, but I didn't
want to void my warranty on the SAME day that it started...I usually wait a 
few months...:-)
-- 
   Andrew <reynhout@cs.uri.edu>
                                     90.3 WRIU Kingston, your sound alternative
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