Apple SCSI cards term power

["Jason Whorton" <jason@microxl.com>]

Hello.  I have a couple of questions concerning the Apple SCSI cards and
termination power.
    I have one of the High Speed cards and it does not have a diode between
L1 and RP2.  Would the diode between L1 and RP2 be the only way that the
term power mod could be made?  I have been reading the FAQ as listed below
and it mentions that some recent cards were modified by Apple to provide
termination power, but mine does not have a diode between L1 and RP2, but it
does seem to work fine on my IIe.  My SCSI system set-up on my IIe was as
follows:

Apple High-Speed SCSI Card
Apple System Cable (25-pin to 50-pin)
Apple Cable Terminator
Apple HD80SC

Does anyone know if the hard drive inside the HD80SC case provides
termination power?  I am going to buy another HD**SC case and a much bigger
hard drive to replace whatever drive is inside it.  I am currently planning
to buy an Apple labelled 500MB HD out of a Macintosh.  Does anyone know if
these drives provide termination power?  The SCSI HD will be the only SCSI
device currently on the SCSI chain, but I am planning on buying a SCSI
CD-ROM at some point on the future.
    Does anyone kave any information on the regular Apple SCSI card?  Since
the FAQ mentions that it does not provide termination power, how can I
modify it to do so?  I have one of those that I am going to put into my IIe
and use with the HD80SC.  The person I got the card from said that some
modification had been made to it.  I don't know what it was.  I think a ROM
chip was replaced, though.  What problems do I need to look out for when
using the regular Apple SCSI card and the HD80SC?  The HD80SC will be the
only SCSI device to ever be on the SCSI chain.
    As always, I appreciate any help anyone can provide.

Thank you,
Jason Whorton
http://www.microxl.com/oldcomputers/main.html




The Apple SCSI cards do not provide termination power (though some recent
Apple Hi-speed SCSI cards were modified by Apple to provide termination
power).



018- How do I modify my Apple Hi-Speed SCSI card to supply
     Termination Power?

     The Apple High Speed SCSI Termination Power modification consists of
adding a diode. It is shown in resource file R009HSSTMOD.GIF from Harold
Hislop
and Dan Brown.

The pic shows a simple sketch of the back of the Apple High Speed SCSI card
near connectors 26-33. The directions say that you connect a 1N914 diode
between
two points:

The anode (non-banded end) of the diode goes to the *top* of L1. The cathode
(banded/striped end) of the diode goes to the >bottom< of RP2

The pic shows the *top* of L1 to be a solder pad (just a solder pad with no
trace
showing) a little ways up from a point between connectors 32 and 33.

The >bottom< of RP2 is just a bit up and to the left of the *top* of L1. It
is
the lowest of several points (the pic shows 8) arranged in a vertical column
and should have a trace going off to the left.