Compact Flash LED not working

You are here:

Some Compact Flash (CF) to IDE adaptors fail to light up the drive activity LED, I was wondering why…

I took a board and removed some components and did some measurements, and I  discovered that the BOTH base pins of the NPN transistors are connected to ground. Huh?! That means that the transistors won’t switch at no circumstance!

 

IDE 44 Pinout
IDE 44 Pinout

 

Partitual schematic of CF to IDE adaptor
Partitual schematic of CF to IDE adaptor

 

If my measurement are correct, the components are connected as the schematic above.

1 = VCC / 5V
2 = GND
3 = DASP_CF
4 = DASP_IDE (on Commodore Amiga called _IDE_LED)

1AM. = 3904 / NPN Transistor

 

Amiga schematic (A600/A1200)

IDE LED schematic of Amiga 600/1200
IDE LED schematic of Amiga 600/1200

How to fix

To fix this there must be a connection between the CF card DASP_CF signal and the DASP_IDE signal. If you take a look at Q1 & Q2 in the schematic you see that the Emiter (1) of Q1 is connected to DASP_CF (3), and the Collector (3) of Q2 is connected to DASP_IDE (4). So to fix the activity LED make a bridge between those two pins, see image below.

Fix mentioned on forums

On many forums you see people fix it like this:

You just can fix it like I showed it, save a wire 🙂

 

Known boards with this problem

  • CF-IDE44/2.0mm ADAPTOR V.B1

Resources

AT Attachment Interface for Disk Drives