Flickering Hard drive LED

[Chartus]

I just installed a CF card as a hard drive.  The problem I have is the HD LED flickers constantly.  The only time it is normal is when there is access to the drive.  It never goes out.  Anyone got any ideas

[the_leander]

You've made sure that you've not somehow reversed the connectors on the LED, right?

[Daedalus]

In the Amiga, the HD LED is connected directly to the IDE port's Drive active/Slave present (_DASP) line, rather than controlled by the IDE controller itself. This means it's totally controlled by the CF card or whatever is plugged into the IDE port, and is the reason that CD drives connected directly to the port cause the HD LED to light for a few seconds during booting. Unfortunately there's probably not much you can do about it, it seems the card might just be constantly switching this line. You could possibly cut that line on the CF adaptor but I don't know if the card requires it. Hard drives as a single device on the bus usually don't have a problem if this line is missing, but of course you can't tell when you're reading or writing.

@the_leander
I would imagine it's already the correct way around as if it was backwards it wouldn't light at all - it's driven by a PNP transistor to reverse the active low _DASP signal, so the polarity isn't reversed to turn off the LED, power is simply cut from it.

*Disclaimer: I'm only this familiar with the A1200 - other Amiga models may be different...

[the_leander]

@the_leander
I would imagine it's already the correct way around as if it was backwards it wouldn't light at all - it's driven by a PNP transistor to reverse the active low _DASP signal, so the polarity isn't reversed to turn off the LED, power is simply cut from it.

I was just thinking that on a few occasions I plugged my floppy drive (or possibly it was the LED lines - cant remember it was over a decade ago) in the wrong way around and it caused the floppy LED to light up permanently (the drive was still operable during this - ticking/reading disks etc) and wondered if something similar might be occurring.

[psxphill]

I was just thinking that on a few occasions I plugged my floppy drive (or possibly it was the LED lines - cant remember it was over a decade ago) in the wrong way around and it caused the floppy LED to light up permanently (the drive was still operable during this - ticking/reading disks etc) and wondered if something similar might be occurring.

I've only seen that with 5 1/4" floppy drives on a pc as the connector wasn't keyed. In that circumstance the drive wouldn't work.
 
So it must have been the led cable, although if it's an a500 then isn't that part of the keyboard? Plugging that the wrong way round could to it I suppose. I haven't opened up any other amigas recent enough to remember if they had seperate wires for the leds.

[the_leander]

I've only seen that with 5 1/4" floppy drives on a pc as the connector wasn't keyed. In that circumstance the drive wouldn't work.
 
So it must have been the led cable, although if it's an a500 then isn't that part of the keyboard? Plugging that the wrong way round could to it I suppose. I haven't opened up any other amigas recent enough to remember if they had seperate wires for the leds.

This was on my A1200. Thinking about it I might be remembering wrong about the drive still working - Once I'd set it up the way I wanted it was rare (as in maybe once in 3 months) that I'd use the floppy drive.

[Thomas]

I've only seen that with 5 1/4" floppy drives on a pc as the connector wasn't keyed.

Then you are lucky. I recently connected a rather new 2.5" floppy drive and the LED was lit all the time although I was absolutely sure that the cable was connected correctly because I checked that the pin on the connector fitted perfectly into the notch on the drive. When I disassembled it again, I noticed that the drive had a notch on both sides, so that the cable fits either way.

You still need to be very careful when connecting computer parts, even nowadays as everything seems to be colored or keyed or whatever to be fool-proof.

[Daedalus]

Yes, a floppy drive connected backwards will cause the activity LED to light permanently as every even (or is it odd?) pin is ground, so turning it around pulls every signal low. In this case it won't work at all

I've noticed this on pretty much any floppy drive from the past decade, notches on both sides. I guess it's just because so many cables were produced the wrong way around that it's a matter of trying it, then swapping it over if it doesn't work. I've found plenty of machines which have what looks like pin 1 mapped to the wrong end of the cable, but the drive works. Thank God for SATA, eh?

[Chartus]

It flickers on both the Hard drive LED and the small LED that is on the CF adapter.  It looks like everything works right though.  I guess I will have to live with it.