As already mentioned, there are some types of CF adapters that do not drive the Amiga 1200’s HDD LED properly. So far I’ve used several adapters labeled V.H2, which all work well.
This really nice purple Amiga 1200 already had a compact flash drive installed. I noticed that the HDD LED was always off. The installed CF adapter has the label V.B1.
Checking the Amiga 1200 schematics, we see that pin 39 of the IDE connector is driving the HDD LED. On the CF card the busy LED signal is coming from pin 45. And indeed, checking continuity on the V.H2, we see that IDE pin 39 is connected to CF card pin 45 DASP. But on the V.B1 they are not connected.
Oddly enough, there is a small LED on the CF adapter board that is already connected to pin 45 of the CF card. And there is a transistor whose pin is connected to IDE pin 39. If we connect those two points, the Amiga’s HDD LED works.
Sources / more infos:
If you check the continuity on the V.B1 adapter you’ll see that the connection you are making at the LED is actually going back to the transistor next to the one you are joining the wire to.
There is no need to run the long wire, just a short connection between the two transistors is needed.
Thanks for the info. Great tip.