Do all FD-1 put 5V on some unused lines of the drive cable or just those, that were sold together with the DDI-1?
Since its so easy to connect the drive in the wrong way, I would see this a major risk to fry your CPC when connecting a drive. Or is that not a problem because the relevant pins are not connected?
It shouldn't be possible to connect the drive connector the wrong way on an original DDI-1 as the connectors had a key-way to stop this. Either way, it wouldn't fry anything as the "wrong" pins are connected to GND, so at most it would fry the FD-1.
Bryce.
Sorry, I didn't mean the DDI-1, I meant a 664 or 6128:
On the CPC the edge connectors could be upside down and on FD-1 side, the cables also can be connected in both directions. There is nothing on the FD-1 or the cable that prevents this. If I understand correctly, the 5V are on pins, that are N/C in the 664 or 6128. But once I accidentally turn the cable on one end, the 5V should end up on some pins, where they do not belong.
Yes, if you put the connector the wrong way around in this case, you would be shorting the 5V ouput of the FD-1 to GND which would most likely damage the FD-1.
Bryce.
OK, thanks a lot.
I am surprised this doesn't happen regularly and that there is almost no warning anywhere. I know that the cables usually have a "this side up" sticker (or similar) but I would not bet that they are present on all cables and except for that, there is nothing that would prevent me from putting it the wrong way into the Fd-1.
The 5V rail in the FD-1 is regulated with a 7805 linear regulator. These are extremely robust, with built-in over-temp and over-current protection and additionally, the flat cable would offer a certain amount of current limiting, so the FD-1 would most likely survive a short if it only occurs for a very short time (no pun intended).
Bryce.
For a 6128 you can put in larger resistor to minimize the risk or cut the line in the cable...
However both methods will turn the cable useless for a DDI-1 interface as it is getting powered from the drive and not from the CPC.
The DDI-1 has its own fixed (non-removable) cable, so you would never be using the 6128 cable on a DDI-1 anyway.
Bryce.
:laugh:
I totally forgot about that ... funny ...
Thanks for correcting me.