Help identifying this tantalum capacitor

bluejay · May 27, 2020

This capacitor fell out of one of my Compaq Portable II power supplies, and the other's is blown. I can't take a focused picture on it, but is says: 15-25 +M(2) and what looks like an arrow. Thanks for the help!

Stephen Moss · May 28, 2020

From that I would say it is a it is 15uF @ 25V.

Usually when you look at them with the reading the correct way up the value is on top, the voltage is below it, the M(2) may refer to construction/ripple current capacity depending on the manufacture.

The + is usually at the end of the line and indicates the positive terminal as being polarised you need to ensure you insert them the correct way round.

Personally, I think you would be better off replacing the power unit rather then just replacing the capacitors. With one blown and the other falling out which may be due to a manufacturing error but alternatively may be due to it going short circuit and getting so hot (280c or more) that the solder melted.

If the latter is what happened it may have caused additional less obvious damage, or other damage may have made it short out, so if you do replace the capacitors you might want to take the precautions of...

a) Being as far away as the power lead allows when you turn it on, because if there is other damage and something does go bang you don't want it doing so in your face.

b) Do not connect the output when you turn it on after repair, instead leave it running for a couple of hours (not unsupervised) with them disconnected first and then check the output voltages are as expected and if it seems excessively hot considering that no current is being taken from it.

If it checks out OK after that and there is more than one output cable being used you might want to consider turning it one with only one output cable connected at a time because if a fault external from the power supply caused the damage knowing which output was connected when it blows again could help narrow down where the fault might be.