ND 7551 not recognized




I’ve got an Asus L5C laptop and just bought the NEC ND 7551 drive.

To my sorrow, the drive is not recognized at all. The Toshiba SD R6112 which came with the Laptop used to operate as Primary Master - which I understand is what the NEC drive should do also.

Anyone know if the Pin 45/47 bridging will work as I assume that no reverse ATA firmware is yet available for this drive?


If there is a BIOS update for your laptop, try it


There is a reverse ATA firmware at Liggy’s web site. But there is no way to go back to original now. So before doing the reverse ATA, make sure that is the real reason.

Laptop BIOS or other software may show the optical drive as 2nd master, but in fact it is not. I have a Toshiba A85. Every software showed it as 2nd master, but I have to do a revere ATA to make my 6650 and 6750 work. Then I have a Toshiba L25. Optical drive also showed as 2nd master. But neither master nor slave mode would work. The original drive is a Toshiba 6112, firmware TU02. I checked the web site and found Toshiba drive comes in 2 flavor, TU for cable select and TR for slave. So my original drive is a cable select. That may be what my L25 need- a cable select drive. There is no software to convert my NEC drive to cable select, so I just gave up.


Well, the latested FW for the laptop is 2.07a, which is what I’ve installed…

The original DVD shows up as primary master, the HDD as secondary master.

Setting the BIOS fixed to CD-ROM PIO 4 / UDMA 5 did not bring up the cdrom (bios would complain about a missing drive).

The Toshiba SD R6112 runs Firmware 1733, as far as I can tell… (Seems there are 10xx and 1Mxx Firmwares also - anyone knows what’s the difference here?)


see this:


My drive is a sd-r2612c, not 6112.

May be 17xx, 10xx, 1Mxx represent master, slave and cable select. Just do not know which is which.


Ok, I found this:


Thus the pin soldering method should work with the ASUS L5C / NEC ND 755x combination to fix the drive to master mode. Just interesting, that the laptop can not communicate with a slave device at all…


It’s only for the 7550. And there is a normal ATA firmware available, but it’s currently untested so I didn’t give access to the file. Someone first has to test it.


Just found out - the ND 7551 is recognized in a FSC notebook (as secondary master) right away - but the ATA reverse Firmware - or check for the drive at least (c7550rge / c75501p1) did not recognize the drive…

Just a question though - if this behaviour (i.e. how the CSEL pin is interpreted) is a firmware thing, why would re-flashing the drive with the original firmware not restore the behaviour (ie - GND = Master, open = Slave - default; GND=Slave, open=Master - reverse).

Would it help to download the current FW of the ND 7551 for you to have a closer peek (don’t yet know which version is running on it)?



Short of soldering something to the PCB next to the connector, and thereby invalidating the warranty, i managed to put a single fine strand of copper cord from the back through to the front, and then twisting it around the GND pins on the opposite side fixed:

49 _ Edge of PCB, below connector
+|++ + + + + + + / / + |
| \ |
+|+ +|+ + + + + + / / + |
## <- twisted cord |
rear of drive

Now the Asus L5C recognizes the drive right away as Primary Master, and it’s running FW 1.02 (for those interested).


I bought a 7551 for my Fujitsu/Siemens Amilo A 1667G but haven’t received it yet. My current drive is a 6650A which came with the laptop and was recognized as master sole device on IDE2 without the need for ATA reversing. This drive has some serious calibration problems so I decided to upgrade. Hopefully the 7551 will be recognized without problems on the Amilo…


If the 6650 worked fine without the need of a slave firmware, the 7751 shouldn’t cause problems either.