You have been directed to this web page because it has been determined that there is a short-circuit on the +5 volt line of your IBM 5150/5155/5160 motherboard.

We know that the short-circuit is on the motherboard because you were earlier instructed to:
1.  Have no expansion cards plugged into the motherboard; and
2.  Have no keyboard plugged into the motherboard.

Unfortunately, over 95% of the components on the motherboard use the +5 volts, and as such, any one of those may have become short-circuit.  However, faulty tantalum capacitors is a very common problem with the 5150/5155/5160 motherboards.  So there is high probability that a tantalum capacitor on the +5 volt line of your motherboard is the component that has become short-circuit.

As described below, the 5150/5155/5160 motherboards have quite a few tantalum capacitors on the +5 volt line.  I recommend that you visually inspect the tantalum capacitors, because if one is faulty, there may be a sign.  What you are looking for is shown here.

If none of the tantalum capacitors show any visual indication of failure, then there is no easy way forward (within the scope of this web page).  If you are desperate, you could try removing all of the tantalum capacitors on the +5 volt line.  You would do that one capacitor at a time, and after each capacitor, seeing if the short-circuit was removed.  Removal by either desoldering, or by using a pair of sidecutters to cut the capacitor off the board.


IBM 5150 (IBM PC) motherboard - type 16KB-64KB

This is the early version of the 5150 motherboard.  It is marked "16KB-64KB CPU"
Six of the seventeen tantalum capacitors that are designated as C7 are on the +5 volt line.
Click here to see a photo that shows the six capacitors.


IBM 5150 (IBM PC) motherboard - type 64KB-256KB

This is the later version of the 5150 motherboard.  It is marked "64KB-256KB CPU"
Ten of the thirteen tantalum capacitors that are designated as C7 are on the +5 volt line.
Click here to see a photo that shows the ten capacitors.


IBM 5155 (IBM Portable PC) motherboard

The 5155 contains an early 5160 motherboard.  Refer to the 5160 motherboard section that follows.


IBM 5160 (IBM XT) motherboard

On a 5160 motherboard (of both types), thirteen of the sixteen tantalum capacitors are on the +5 volt line.
Click here to see a photo that shows the thirteen capacitors.