DOA keyboard…is there an easy fix?

Lock LED's won’t light and keys don’t respond--completely dead. After Newegg told me just to keep it and they’ll send me another, I took the back off and fiddled with the main connection and small circuit board but still…nothing. Does anyone know what the problem may be? My first thought, of course, is a bad connection in the main line (PS/2)so I've done the very basics (while connected: checked connection, moved plug around, "hand walked" wire-ie. push-pull every few inches while connected, inspected circuit board, inspected connection to circuit board and...well, damn, it's just a keyboard; how much can there be to check?)

No big deal but if there’s a simple fix I’d just assume fix it than trash it.

I deal with dead keypads for industrial equipment all the time. A keyboard for a computer is just a biggger version of the common keypad.

If truly dead the most likely the problem is on the keypad 's (key board's) circuit board. Circuit boards of all kinds can be damaged in shipping, and a small piece of flux (that should have be cleaned off in manufacturing) can easily shortout a circuit board component often without a leaving much of a visible trace.

Circuit boards can also get overloaded during install-uninstall process. Sometimes allowing the board to set for a period of time will cause the board to clear the error and reset itself. Often there there is a reset on the circuit board, but performing the reset may be beyond the average Joe Blow that can't install a stick of RAM so the keyboard manufacturer may not even publish the reset sequence (calling the manufacturer's 3rd tier tech support might give you the reset code).

In addition, a lot of devices will have a stepup or stepdown transformer for conversion of power. Sometimes the transformer is a powerstage on the circuit board, but not always. The windings on the transformer can be shorted by debris and manufacturing flux. Trying to find a short on the windings of a minature transformer is not something for the hobbiest eyeballing the part.

Some keyboards use a rubber type sheeting between the keys and sensors. This type of arrangement is very common with low cost keyboards and calculators. When the key is struck the back side of the rubber sheeting has an electrical connection that strikes the appropriate sensor and completes the kkeyboard signal. There have been problems with the rubber sheeting being contaminated and conducting an electrical signal without any keys being struck. That spurious signal can overload the circuit board and causes board confussion and shutdown, or the spurious signal will cause multiple strikes of the specific key.

Other keyboards (those fancy ones) use a sealed membrane with keys printed on the sealed membrane which completes an electrical signal when the key is pressed. Moisture seeping into the sealed membrane will cause complete membrane failure.

Then again, a key could have been forcefully struck during shipping and the pickup sensor is reading a continous signal. This is a problem as the keyboard must often "zero" itself during startup. I have had customers hold down a key on the keypad (by resting their hand on the keypad) for a piece of equipment and the unit will not start until their hand is removed the unit again goes through the startup sequence.

In other words chasing a keypad / keyboard failure can be quite intensive.

But think about this.... if Newegg is sending ya a replacement and they DON"T want the bad one back.... then that bad one must not be worth much money. So chasing your tail trying to find the defect/damage may not be very practical.

Personally I would chunk the old keyboard and use the replacement.