On Mon, Oct 12, 2020 at 4:04 PM Chris Zach <c...@alembic.crystel.com> wrote: > > > 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'm pretty sure it's on the PCB. > > 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
