12 Oct
2020
12 Oct
'20
8:11 a.m.
On Mon, Oct 12, 2020 at 4:04 PM Chris Zach <cz at alembic.crystel.com> wrote:
I'm pretty sure it's on the PCB.
In a 'real' RX01, each sensor LED (track
0 and index) has the cathode
grounded and the anode connected to +5V via a 68ohm series resistor.
If you measure the voltage across the pins with the LED disconnected
(or if the LED is open-circuit) with any reasonable meter, it'll read
5V. The meter will not draw enough current for the resistor to drop a
noticeable voltage.
Ok, that makes sense. Is the resistor on the board or on the drive wire
harness somewhere?
I'll jumper the disk 0 sensor into my test board here (actually just the
extender board from another PDT11) and see what the voltage looks like,
then compare it to the same spot on the second drive.
I'd look at the voltage on each pin of the LED in the 3 other sensors
(index and track 0 for both drives)
-tony