1 Jan
2008
1 Jan
'08
8:55 a.m.
From: lynchaj at yahoo.com
---snip---
Hi Chuck,
Yes you are correct. I spoke with the VG engineer to get more details on
"constant index" and you described it exactly.
Apparently there is a cut and jumper modification which can be made to the
ST506 circuit board to bring the /INDEX signal to the interface constantly
even when the drive is not selected.
Once I get a ST506 drive I will find and make the modification. Assuming I
can get the ST506 to work, I will try making modifications to ST225's or
other more common hard drives.
I'd like to get the standard case working to establish if my VEDMCS is
working properly before adding in other variables of different drives etc.
Hi Andrew
When you find your drive, it should be easy to make the mod.
Follow the signal back from the pin. There should be a line
driver there. Usually something like a 74S38 or a 7545x.
These usually have two inputs. Using a scope or a logic probe,
you'll see one input with the index and the other will be
static. The static one is the one to tie high to get a constant
Index. The easiest way is to cut the IC lead near the board
and lift it away a little. You can then put a pullup resistor
on this lead.
I like doing this more than cutting the circuit board.
If restoring, one can replace the IC or just bend the lead back
solder it back.
Dwight
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