|It is common to un-intentionally damage IDE data cables, especially while removing them - the 80 wire ones are more likely to be damaged. What usually happens is the cable is ripped at either edge and the wires there are either damaged or severed, often right at a connector or under it's cable clamp there, where it's hard to see - if a wire is severed but it's ends are touching, the connection is intermittant, rather than being reliable. |
Another common thing is for the data cable to be separated from the connector contacts a bit after you have removed a cable - there should be no gap between the data cable and the connector - if there is press the cable against the connector to eliminate the gap.
80 wire data cables are also easily damaged at either edge if the cable is sharply creased at a fold in the cable.
Try another data cable if in doubt.
Some IDE hard drives, e.g. many Western Digital models, have TWO ways they can be jumpered as master. E.g. master (single), or similar, for when the drive is connected by itself on a data cable, and master (with slave), or similar, for when the drive is connected to a data cable that has another drive jumpered as slave.
If that applies to your case, if you have two drives on the same data cable and one hard drive is set to master (single), or similar, then the drive jumpered as slave is usually not seen properly.
Or - jumper both drives CS - cable select. The drive on the middle connector is then seen as slave, the one on the end connector is then seen as master.
Or, rarely, if you reverse which drive is master, which is slave, if they are not identical, then sometimes that allows both drives to be seen properly, when that did not work the other way.
The proper end connector on 80 wire data cables MUST be connected to the mboard - usually that's blue, but in any case it's the one farther from the middle connector on a 3 connector data cable.
Sometimes the jumper info on a label can be confusing - it may be upside down with respect to where the jumpers are. If the power connector is shown relative to the jumper positions, go by that, or consult the jumper info for the model on the manufacturer's web site. Different brands or different models made by the same brand may not have jumpers in the same places, and in some cases you do not need to install a jumper for one of slave or master.